Thunder Scientific 3900 User guide

OPERATION AND MAINTENANCE MANUAL

LOW HUMIDITY GENERATOR

SERIES 3900

®

MADE IN USA

SERIES 3900

LOW HUMIDITY GENERATOR

OPERATION AND

MAINTENANCE MANUAL

Copyright © 1993-2018

THUNDER SCIENTIFIC CORPORATION

623 WYOMING BLVD. SE

ALBUQUERQUE, NEW MEXICO 87123-3198

www.thunderscientific.com

Printed 2018

Tel: [phone]  FAX: [phone]

E-mail: [e-mail]

Document Edition 16  June 2018
Firmware Version 2.12

THUNDER SCIENTIFIC® is the registered trademark of Thunder Scientific Corporation.
All the information provided in this document is correct and true at the time of publication.
Thunder Scientific Corporation reserves the right to change any technical data without notice.

Model 3900 Low Humidity Generator

i

TABLE OF CONTENTS

Section 1 - GENERAL INFORMATION

List of Reference Drawings - iv

Warranty

1.1 INTRODUCTION ---------------------------------------------------------------- 1-1

1.2 PRINCIPLE OF OPERATION ------------------------------------------------- 1-1

1.2.1 General Description --------------------------------------------------------- 1-1

1.2.2 Humidity Formulas --------------------------------------------------------- 1-1

1.2.2.1 Saturation Vapor Pressure, e ----------------------------------------- 1-2

1.2.2.2 Enhancement Factor, ƒ ----------------------------------------------- 1-3

1.2.2.3 Frost Point -------------------------------------------------------------- 1-4

1.2.2.4 Dew Point -------------------------------------------------------------- 1-5

1.2.2.5 Parts Per Million by Volume, PPMv ------------------------------- 1-5

1.2.2.6 Parts Per Million by Weight, PPMw ------------------------------- 1-6

1.2.2.7 Relative Humidity, %RH --------------------------------------------- 1-6

1.3 SPECIFICATIONS --------------------------------------------------------------- 1-7

1.3.1 Facility Requirements ------------------------------------------------------ 1-7

1.3.2 Environmental --------------------------------------------------------------- 1-7

1.4 COMPUTER/CONTROL SYSTEM ------------------------------------------ 1-8

1.4.1 General Description --------------------------------------------------------- 1-8

1.4.2 Computer/Control System Configuration ------------------------------- 1-8

1.4.2.1 Central Processing Unit (CPU) -------------------------------------- 1-8

1.4.2.2 Liquid Crystal Display (LCD) --------------------------------------- 1-9

1.4.2.3 Liquid Crystal Display Driver --------------------------------------- 1-9

1.4.2.4 Keypad ------------------------------------------------------------------ 1-9

1.4.2.5 Memory Card ---------------------------------------------------------- 1-9

1.4.2.6 Analog to Digital Converter (A/D) --------------------------------- 1-9

1.5 ELECTRICAL SYSTEM ------------------------------------------------------- 1-10

1.5.1 AC Power Distribution ---------------------------------------------------- 1-10

1.5.2 Power Supply ±15, +5 VDC ---------------------------------------------- 1-10

1.5.3 Power Supply +24 VDC -------------------------------------------------- 1-10

1.5.4 Analog Inputs --------------------------------------------------------------- 1-11

1.5.4.1 Temperature Measurement ------------------------------------------ 1-11

1.5.4.2 Test Pressure Transducer -------------------------------------------- 1-11

1.5.4.3 Low Range Saturation Pressure Transducer ---------------------- 1-12

1.5.4.4 High Range Saturation Pressure Transducer --------------------- 1-12

1.5.4.5 Gas Supply Pressure Transducer ----------------------------------- 1-12

1.5.4.6 Mass Flow Meter ----------------------------------------------------- 1-12

1.5.5 Control Logic --------------------------------------------------------------- 1-13

1.5.5.1 Gas Supply Solenoid Valve ----------------------------------------- 1-13

1.5.5.2 Fluid Pump Purge Solenoid Valve --------------------------------- 1-13

ii

1.5.5.3 Saturator Vent/Purge Solenoid Valve ----------------------------- 1-13

1.5.5.4 Pressure Select Solenoid Valve ------------------------------------ 1-13

1.5.5.5 Saturator Refrigerant Solenoid Valve ----------------------------- 1-14

1.5.5.6 Saturator Inlet/Outlet Heater --------------------------------------- 1-14

1.5.5.7 Saturator Fluid Heater ----------------------------------------------- 1-14

1.5.5.8 Saturator Fluid Circulation Pump --------------------------------- 1-14

1.5.5.9 Saturator Refrigeration Compressors ----------------------------- 1-14

1.5.5.10 Flow Control Valve ------------------------------------------------------- 1-15

1.5.5.11 Expansion Valve ----------------------------------------------------------- 1-15

1.5.5.12 Expansion Valve Heater -------------------------------------------------- 1-15

1.6 PNEUMATIC SYSTEM ------------------------------------------------------- 1-16

1.7 FLUID SYSTEMS -------------------------------------------------------------- 1-16

1.7.1 Saturator Fluid Systems --------------------------------------------------- 1-16

1.8 REFRIGERATION ------------------------------------------------------------- 1-17

1.8.1 Saturator Refrigeration ---------------------------------------------------- 1-17

Section 2 - INSTALLATION

2.1 GENERAL ------------------------------------------------------------------------- 2-1

2.2 FACILITIES REQUIRED ------------------------------------------------------- 2-1

2.2.1 Floor Space ------------------------------------------------------------------- 2-1

2.2.2 Power -------------------------------------------------------------------------- 2-1

2.2.3 Gas Supply -------------------------------------------------------------------- 2-1

2.3 PREPARATION ------------------------------------------------------------------ 2-1

2.3.1 Methanol Filling Procedure ------------------------------------------------ 2-2

2.3.2 Vent Muffler ------------------------------------------------------------------ 2-3

2.4 POSITIONING AND LEVELING --------------------------------------------- 2-3

2.5 FACILITY CONNECTIONS ---------------------------------------------------- 2-3

2.5.1 Gas Supply -------------------------------------------------------------------- 2-3

2.5.2 Pressure Vent ----------------------------------------------------------------- 2-3

2.5.3 AC Power --------------------------------------------------------------------- 2-3

Section 3 - OPERATION

3.1 GENERAL ------------------------------------------------------------------------- 3-1

3.2 STANDARD OPERATING PROCEDURES -------------------------------- 3-1

3.2.1 Power-Up --------------------------------------------------------------------- 3-1

3.2.2 Control/Display Screen ----------------------------------------------------- 3-1

3.2.2.1 Changing the Display Contrast -------------------------------------------- 3-3

3.2.3 Changing Setpoints ---------------------------------------------------------- 3-4

3.2.3.1 Example Setpoint Change -------------------------------------------- 3-5

3.2.4 Control Modes --------------------------------------------------------------- 3-7

3.2.4.1 Changing Control Mode ---------------------------------------------- 3-8

3.2.5 Purging ---------------------------------------------------------------------- 3-10

iii

3.2.5.1 Purging Procedure ---------------------------------------------------- 3-11

3.2.6 Saturator Clear -------------------------------------------------------------- 3-12

3.2.6.1 Saturator Clear Procedure ------------------------------------------- 3-12

3.2.7 Generating ------------------------------------------------------------------- 3-13

3.2.7.1 Generating Procedure ------------------------------------------------ 3-14

3.2.7.2 Example Instrument Set-up ----------------------------------------- 3-15

3.2.8 Saturator Fill ---------------------------------------------------------------- 3-16

3.2.8.1 Saturator Fill Procedure --------------------------------------------- 3-16

3.2.9 Stopping --------------------------------------------------------------------- 3-18

3.2.10 Shutdown -------------------------------------------------------------------- 3-19

3.2.11 Changing Gas Supply ------------------------------------------------------ 3-19

3.2.12 Printer (optional) ----------------------------------------------------------- 3-19

3.3 EDITING SYSTEM COEFFICIENTS AND PARAMETERS ---------- 3-20

3.3.1 Edit Mode ------------------------------------------------------------------- 3-20

3.3.2 Coefficients and Parameters ---------------------------------------------- 3-22

3.3.2.1 Temperature Coefficients ------------------------------------------- 3-22

3.3.2.2 Reference Resistor Coefficients ------------------------------------ 3-23

3.3.2.3 Pressure Coefficients ------------------------------------------------- 3-23

3.3.2.4 Flow Coefficients ----------------------------------------------------- 3-24

3.3.2.5 Console Port Parameters -------------------------------------------- 3-25

3.3.2.6 Printer Port Parameters ---------------------------------------------- 3-26

3.3.2.7 Time and Date -------------------------------------------------------- 3-26

3.3.2.8 Miscellaneous User Parameters ------------------------------------ 3-27

Section 4 - CALIBRATION AND MAINTENANCE

4.1 GENERAL ------------------------------------------------------------------------ 4-1

4.2 CALIBRATION ------------------------------------------------------------------ 4-1

4.2.1 A/D Card --------------------------------------------------------------------- 4-2

4.2.2 Temperature Calibration --------------------------------------------------- 4-2

4.2.2.1 Test Temperature Calibration Procedure --------------------------- 4-3

4.2.2.2 Saturation Temperature Calibration -------------------------------- 4-7

4.2.3 Pressure Transducer Calibration ----------------------------------------- 4-11

4.2.3.1 Saturator and Test Pressure Calibration Procedure -------------- 4-12

4.2.3.2 Supply Pressure Transducer Calibration -------------------------- 4-16

4.2.4 Flow Meter Calibration --------------------------------------------------- 4-18

4.2.4.1 Flow Calibration Procedure ----------------------------------------- 4-18

4.2.5 Printing Condensed Coefficient Report --------------------------------- 4-22

4.3 ROUTINE MAINTENANCE -------------------------------------------------- 4-23

4.3.1 Console Intake: Monthly -------------------------------------------------- 4-23

4.3.2 7 Micron Gas Input Filter: Yearly --------------------------------------- 4-23

4.4 SERVICING REFRIGERATION AND FLUID SYSTEMS -------------- 4-24

4.4.1 Fault Isolation and Diagnosis --------------------------------------------- 4-24

4.4.1.1 Moisture In Low Stage----------------------------------------------- 4-24

4.4.1.2 Oil In Low Stage Evaporator --------------------------------------- 4-25

iv

4.4.2 Refrigerant Charge -------------------------------------------------------- 4-25

4.4.3 Saturator Fluid System ---------------------------------------------------- 4-25

4.4.4 Methanol System Drain/Fill Procedure --------------------------------- 4-25

4.5 ERROR CODES AND TROUBLESHOOTING --------------------------- 4-27

Section 5 - PARTS LIST

5.1 3900 PARTS LIST ---------------------------------------------------------------- 5-1

LIST OF REFERENCE DRAWINGS

DRAWING # DRAWING TITLE

94D39901 -------------------------Mechanical/ Utility

95D39902 -------------------------Component Locations

95D39903 -------------------------Card Cage and Card Locations

95D39904 -------------------------3900 Bus Diagram

95D39905 -------------------------Electrical Sub-Panel Layout

95S39906 --------------------------Terminal Layout

95S39907 --------------------------AC/DC Power Schematic

95S39908 --------------------------Solid State Relay Module Board

95S39909 --------------------------Compressor / Heater / Alarm Schematic

95S39910 --------------------------Flow Valve Drive Schematic

95S39911 --------------------------Expansion Valve Drive Schematic

95S39912 --------------------------Temperature Probe / Transducer Schematic

95S39913 --------------------------Display Block Diagram

95D39914 -------------------------RS-232C Console / Printer

95S39915 --------------------------Pneumatic System (Generate Mode)

95S39916 --------------------------Pneumatic System (Purge Mode)

95S39917 --------------------------Refrig And Fluid Flow - Saturator

95S39918 --------------------------Test Temp/Test Press Xducer Schematic

08S39921 --------------------------3900 Card Cage Schematic

08D39922 -------------------------Methanol Fill Level Drawing

15A39504 -------------------------4-Port Sample Cell Manifold

WARRANTY

Thunder Scientific Corporation (TSC) warrants, to the Buyer, the Product
manufactured by TSC to be free of defects in material and workmanship
under normal use and service and to be free from inadequate mechanical
design when operated within the specified design limitations for a period
of one year from date of acceptance. TSC's obligation under this warranty
shall be limited to the following: the Product is returned to TSC with
transportation charges prepaid and that TSC's examination reveals the
Product to be defective. TSC, at its option, shall either refund to the Buyer
the purchase price of the product or repair or replace at TSC's plant, any
part or parts of the Product which is or are defective. This warranty shall
not apply to any Product which has been maintained, handled, stored,
repaired or altered in any manner, or by anyone other than an authorized
TSC representative, so as to affect adversely such Product or which has
been subject to improper installation, misuse, negligence, accident or
corrosion. THIS WARRANTY IS EXCLUSIVE AND IN LIEU OF ANY
WARRANTY OF MERCHANTABILITY, FITNESS FOR A
PARTICULAR PURPOSE OR ANY OTHER WARRANTY, WHETHER
EXPRESS OR IMPLIED, AND ALL OTHER LIABILITIES AND
OBLIGATIONS ON THE PART OF TSC; TSC SHALL NOT BE
LIABLE FOR ANY OTHER CLAIMS OR DAMAGES, EITHER
DIRECT OR CONSEQUENTIAL, ARISING DIRECTLY OR
INDIRECTLY OUT OF SUPPLYING THE PRODUCT. All warranties,
express or implied, with respect to any device or component not
manufactured by TSC but incorporated into its Product are the
responsibility of the original manufacturer and shall not affect or apply to
TSC.

Thunder Scientific®
Corporation

Item Check List

3900

ertificate of Calibration (In Manual)

1. C

2. Operation and Maintenance Manual

3. HumiCalc® with Uncertainty Software Download

4. 3900 ControLog® Software Download

5. 5/32” Ball Driver Tool

6. Power Cable

7. Transducer Test Pressure Cable

8. Test Temp Cable

9. Printer Cable

10. Computer IO Control Cable

11. Pure Water Fill Funnel

12. 1/4” 30 Micron Muffler

13. Pressure Transducer 0 – 50 Psi

14. 1/4” Swage x 9/16” – 18 STD

Thunder Scientific Corporation Web: www.thunderscientific.com
623 Wyoming Blvd. SE E-mail: [e-mail]

Albuquerque, NM 87123 Phone: [phone]

Suomi

English

Tämä tuote noudattaa WEEE-direktiivin (2002/96/EY)
merkintävaatimuksia. Kiinnitetty etiketti osoittaa, että tätä
sähkö-/elektroniikkalaitetta ei saa hävittää kotitalousjätteissä.

Tuoteluokka: Viitaten WEEE-direktiivin liitteessä I mainittuihin
laitteisiin, tämä tuote on luokiteltu luokan 9 “Tarkkailu- ja
ohjauslaitteet” -tuotteeksi.

Ei saa heittää kotitalousjätteiden mukana!

Palauta tarpeettomat tuotteet ottamalla yhteyttä valmistajan
websivustoon, joka mainitaan tuotteessa tai paikalliseen
myyntitoimistoon tai jakelijaan.

Dansk

Dette produkt er i overensstemmelse med kravene om afmærkning
i WEEE-direktivet (2002/96/EC). Det påhæftede mærkat angiver,
at du ikke må bortskaffe dette elektriske/elektroniske produkt via
husholdningsaffald.

Produktkategori: Med reference til kravene i WEEE-direktivets
bilag I klassificeres dette produkt som et produkt til “overvågning
og kontrolinstrumentering” i kategori 9.

MÂ ikke bortskaffes via husholdningsaffald!

Hvis du vil returnere uønskede produkter, skal du besøge
producentens websted, som vises på produktet, eller den lokale
forhandler eller distributør.

This product complies with the WEEE Directive (2002/96/EC) marking
requirements. The affixed label indicates that you must not discard
this electrical/electronic product in domestic household waste.

Product Category: With reference to the equipment types in the
WEEE Directive Annex I, this product is classed as category 9
“Monitoring and Control Instrumentation” product.

Do not dispose in domestic household waste!

To return unwanted products, contact the manufacturer’s web site
shown on the product or your local sales office or distributor.

Français

Ce produit est conforme aux normes de marquage de la directive
DEEE (2002/96/CE). La présence de cette étiquette indique que
cet appareil électrique/électronique ne doit pas être mis au rebut
avec les déchets ménagers.

Catégorie de EEE : Cet appareil est classé comme catégorie 9 parmi
les « instruments de surveillance et de contrôle » en référence aux
types d’équipements mentionnés dans l’Annexe I de la directive DEEE.

Ne pas éliminer avec les autres déchets ménagers !

Pour renvoyer les produits indésirables, contacter le site Web du
fabricant mentionné sur le produit, ou son distributeur ou bureau de
ventes local.

Español

Este producto cumple la Directiva WEEE (2002/96/EC) sobre
requisitos de las marcas. La etiqueta que lleva pegada indica
que no debe desechar este producto eléctrico o electrónico con
los residuos domésticos.

Categoría del producto: con referencia a los tipos de equipo
del anexo I de la Directiva WEEE, este producto está clasificado
como categoría 9 de “Instrumentación de supervisión y control”.

¡No lo deseche con los residuos domésticos!

Para devolver productos que no desee, póngase en contacto con
el sitio Web del fabricante mostrado en el producto, o con la oficina
de ventas o distribuidor local.

PN 2566073, 1/2006

Deutsch

Nederlands

Dieses Produkt stimmt mit den Kennzeichnungsanforderungen
der WEEE-Richtlinie (2002/96/EC) überein. Das angebrachte
Etikett weist darauf hin, dass dieses elektrische/elektronische
Produkt nicht in Hausmüll entsorgt werden darf.

Produktkategorie: In Bezug auf die Gerätetypen in Anhang
I der WEEE-Richtlinie ist dieses Produkt als Kategorie 9
“Überwachungs- und Kontrollinstrument” klassifiziert.

Nicht in Hausmüll entsorgen!

Zur Rückgabe von unerwünschten Produkten die auf dem
Produkt angegebene Website des Herstellers oder die zuständige
Verkaufsstelle bzw. den zuständigen Fachhändler konsultieren.

Italiano

Questo prodotto risponde ai requisiti sull’etichettatura stabiliti
nella Direttiva RAEE (2002/96/CE). Il simbolo apposto indica che
non si deve gettare questo prodotto elettrico o elettronico in un
contenitore per rifiuti domestici.

Categoria del prodotto: con riferimento ai tipi di apparecchiature
elencate nell’Allegato 1 della Direttiva RAEE, questo prodotto
rientra nella categoria 9 “Strumenti di monitoraggio e di controllo”.

Non gettare in un contenitore per rifiuti domestici.

Per restituire prodotti non desiderati, visitare il sito Web del
produttore riportato sul prodotto o rivolgersi al distributore o
all’ufficio vendite locale.

Dit product voldoet aan de merktekenvereisten van de AEEA­richtlijn (2002/96/EG). Het aangebrachte merkteken duidt erop dat
dit elektrische/elektronische product niet met het huishoudelijk
afval mag worden afgevoerd.

Productcategorie: Met betrekking tot de apparatuurcategorieën
van bijlage I van de AEEA-richtlijn, valt dit product onder categorie
9 ‘meet- en controle-instrumenten’.

Niet afvoeren met huishoudelijk afval!

Om ongewenste producten te retourneren, neemt u contact op
met de website van de fabrikant die op het product staat vermeld,
of met uw plaatselijke verkoopkantoor of distributeur.

Svenska

Denna produkt uppfyller märkningskraven enligt WEEE Directive
(2002/96/EC). Märkningsetiketten anger att du inte får kassera denna
elektriska/elektroniska produkt tillsammans med vanliga hushållssopor.

Produktkategori: Med hänvisning till utrustningstyperna i
WEEE Directive Annex I, är denna produkt klassad som kategori 9
“Monitoring and Control Instrumentation” (Instrument för
övervakning och styrning).

Får ej kasseras tillsammans med vanliga hushållssopor!

Returnera ej önskvärda produkter genom att gå till tillverkarens
webbplats, vilken anges på produkten, eller till det lokala
försäljningskontoret eller distributören.

Português

Este produto está em conformidade com as exigências de rotulagem
da Directiva WEEE (2002/96/EC). O rótulo afixado indica que o
utilizador não deve deitar este produto eléctrico/electrónico fora
juntamente com o lixo doméstico.

Categoria do produto: No que se refere aos tipos de equipamento lis­tados no Anexo I da Directiva WEEE, este produto está classificado como
produto da categoria 9, “Instrumentação de monitorização e controlo”.

Não deite fora juntamente com o lixo doméstico!

Para devolver produtos indesejados, contacte o fabricante através do
Website constante do produto ou contacte o seu representante de
vendas ou distribuidor local.

Norsk

Dette produktet oppfyller bestemmelsene ifølge WEEE-direktiv
(2002/96/EC) med krav til merking. Påsatt merke viser at det ikke
er tillatt å kassere dette elektriske/elektroniske produktet sammen
med husholdningsavfall.

Produktkategori: På grunnlag av utstyrstypene i WEEE­direktivet, vedlegg I, er dette produktet klassifisert i kategori 9,
“Instrumentering for overvåking og kontroll”.

Må ikke kastes sammen med husholdningsavfall!

Ved behov for returforsendelse av uønskede produkter må du gå
til produsentens nettside som er angitt på produktet, eller du må
kontakte det lokale salgskontoret eller den lokale forhandleren.

Section 1

GENERAL INFORMATION

1.1 INTRODUCTION

The Model 3900 low humidity generating system is a facility capable of producing known
humidity values using the combined fundamental principles of the "two temperature" and
"two pressure" generators developed by NIST. This system is capable of continuously
supplying accurately known humidity values for instrument calibration and evaluation.
When used within the specified frost point range of -95.00 °C to 10.00 °C, the system will
generate manually entered setpoints for days or even weeks unattended.

The 3900 operates using an embedded computer and control system to perform calculation
and control functions. The Computer Control System utilizes a multifunction CPU in
conjunction with other peripheral cards for control and is incorporated into the 3900 low
humidity generator. Peripheral equipment, such as a printer or computer, may be connected
using the bi-directional RS-232C interfaces.

Humidity and temperature setpoint values are input by the operator from the front panel
keypad. The system is then automatically controlled at a setpoint, with visual indications of
system status displayed in real time on the Liquid Crystal Display. The automatic features of
this system allow the 3900 to generate humidity and temperature setpoints completely
unattended, freeing the operating technician from the task of system monitoring and
adjustment.

1.2 PRINCIPLE OF OPERATION

1.2.1 General Description

The Model 3900 humidity generation system is based on the "two temperature - two
pressure" principle. This process involves saturating air or some other gas, such as nitrogen,
with water vapor at a given temperature and pressure. The saturated high pressure gas is then
reduced to test pressure and warmed to test temperature. The indication of saturation
temperature, saturation pressure, test temperature, and test pressure may be used in the
determination of all hygrometric parameters. Humidity generation by this system does not
depend upon measuring the amount of water vapor, but rather is dependent on the
measurements of temperature and pressure alone. The precision of the system is determined
by the accuracy of the temperature and pressure measurements, and on the constancy of them
throughout.

1.2.2 Humidity Formulas

The humidity (or water vapor content) of a gas may be expressed in a variety of ways. The
humidity parameters available with the 3900, and the formulas used to derive them, will be
expressed in terms of the two-temperature two-pressure generator. While some basic
understanding of humidity is helpful, thorough knowledge of the following formulas and
their relationships to the 3900 is not a requirement for successful operation of the generator.

1-1

(

)



















+

+















+

−

=











∑

15

.

273ln

15

.273

2

6

0

TD

TC

i

i

i

(

)

( )



















++















+

−

=

∑

15.273ln15.273

1

5

0

TDTC

i

i

i

1.2.2.1 Saturation Vapor Pressure, e

Saturation Vapor Pressure (SVP) is the pressure exerted by water vapor alone when in
equilibrium with pure ice or water, and is expressed as a function of temperature only. Since
SVP can be established with respect to either ice or water, two separate formulas are used.
Wexler's1 formula for SVP over water is expressed as

ew(T) = exp

where C0 = -2.9912729 x 103
C1 = -6.0170128 x 103
C2 = 1.887643854 x 101
C3 = -2.8354721 x 10-2
C4 = 1.7838301 x 10-5
C5 = -8.4150417 x 10
C6 = 4.4412543 x 10

-10

-13

D = 2.858487
T = temperature of the gas in °C.

For SVP over ice, the equation of Hyland & Wexler2 is expressed as

ei(T) = exp

where C0 = -5.6745359 x 103

C1 = 6.3925247
C2 = -9.6778430 x 10-3
C3 = 6.2215701 x 10-7
C4 = 2.0747825 x 10-9
C5 = -9.4840240 x 10

-13

D = 4.1635019
T = temperature of the gas in °C.

(1)

(2)

1

Wexler, Arnold, Vapor Pressure Formulation for Water in Range 0 to 100 °C. A Revision., Journal of Research of the

National Bureau of Standards - A. Physics and Chemistry, Vol. 80A, Nos. 5 and 6, September-December 1976, pp. 775­785, Equation 15.

2

Hyland, Richard, and Wexler, Arnold, Formulations of the Thermodynamic Properties of the Saturated Phases of H2O

from 173.15 K to 473.15 K, Ashrae Transactions 1983, Part 2A, pp. 500-513, Equation 18

1-2

1.2.2.2 Enhancement Factor, ƒ

(

)





























−

+











−











1

1

Te

P

P

Te

w

w

β

α

∑

=

3

0i

i

i

TA

B

i

T

i

i =

0

3

∑

(

)





























−+















−











11

Te

P

P

Te

i

i

βα

The enhancement factor, ƒ, corrects for the non-ideal behavior of air when it is used as the
carrier gas. The enhancement factor is a function of two independent variables; pressure, P,
and temperature, T. A formula for calculation of the enhancement factor at any given
pressure and temperature above freezing is given by Greenspan

1

as

ƒw(T,P) = exp

(3)

where P = the absolute pressure in Pascals, and

ew(T) = the saturation vapor pressure (in Pascals) at
temperature, T.

The two remaining variables, α and β, are given as

α =

β = exp

where A0 = 3.53624 x 10
A1 = 2.93228 x 10
A2 = 2.61474 x 10

-4

-5

-7

A3 = 8.57538 x 10-9
B0 = -1.07588 x 101
B1 = 6.32529 x 10
B2 = -2.53591 x 10

-2

-4

B3 = 6.33784 x 10-7, and
T = temperature of the gas in °C.

This formula for the enhancement factor is valid over the pressure range of the 3900 and over
the temperature range of 0 to 100 °C.

When calculating enhancement factors with respect to ice for temperatures from -100 to 0 °C,
the formula becomes

ƒi(T,P) = exp

(4)

where P = the absolute pressure in Pascals, and

ei(T) = the saturation vapor pressure (in Pascals) at
temperature, T.

1

Greenspan, Lewis, Functional Equations for the Enhancement Factors of CO2-Free Moist Air, Journal of Research of the

National Bureau of Standards - A. Physics and Chemistry, Vol. 80A, No.1, January-February 1976, pp. 41-44

1-3

Again the variables, α and β, are given as

A

i

T

i

i

=

0

3

∑

B

i

T

i

i =

0

3

∑

ƒ

(Ts,

Ps)∗e (Ts)∗P

c

ƒ(Tf,Pc)∗P

s

t eiT

f

( )

α =

and β = exp

where A0 = 3.6449 x 10
A1 = 2.93631 x 10
A2 = 4.88635 x 10

-4

-5

-7

A3 = 4.36543 x 10-9
B0 = -1.07271 x 101
B1 = 7.61989 x 10
B2 = -1.74771 x 10

-2

-4

B3 = 2.46721 x 10-6, and
T = temperature of the gas in °C.

1.2.2.3 Frost Point

Frost point temperature, Tf, is the temperature to which a gas must be cooled in order to just
begin condensing water vapor in the form of ice or frost. For this reason, frost point is not
applicable above freezing. In relation to the two-temperature two-pressure generator, frost
point vapor pressure is derived from the formula

ei(Tf) =

(5)

where ƒ(Ts,Ps) = the enhancement factor at saturation temperature, Ts,

and saturation pressure, Ps

ƒ(Tf,Pt) = the enhancement factor at the frost point temperature,

Tf, and test pressure, Pt. (Since frost point is not known, this

equation is solved by iteration.)

e(Ts) = the SVP (ei or ew) at saturation temperature, Ts
Pt = the absolute test pressure, Pt
Ps = the absolute saturation pressure, Ps.

Then frost point temperature relative to that vapor pressure is solved for as the inverse of the
SVP formula (see equation 2 section 1.2.2.1)

Tf =

(6)

where ei(Tf) = SVP over ice at the frost point temperature, Tf,

obtained from equation 5.

The 3900 generates a particular frost point by first selecting a suitable saturation temperature,

Ts, then determining the saturation pressure, Ps, required to establish the correct frost point

vapor pressure (and ultimately the correct frost point temperature) at any given test pressure,

Pt. Frost point is independent of test temperature.

1-4

1.2.2.4 Dew Point

ƒ(

Ts,

P

s

)∗e

(T

s

)∗P

t

ƒ(

Td,

Pt)

∗

P

s

t e

w

T

d

( )

ƒ(T

s

, Ps)∗e( Ts)

Ps−

ƒ(Ts,

P

s

)∗e(Ts)

∗

10

6

Dew point temperature, Td, is the temperature to which a gas must be cooled in order to just
begin condensing water vapor in the form of dew. Unlike frost point, dew point can exist
both above and below freezing. In relation to the two-temperature two-pressure generator,
dew point vapor pressure is derived from the formula

ew(Td) =

(7)

where ƒ(Ts,Ps) = the enhancement factor at saturation temperature, Ts,

and saturation pressure, Ps

ƒ(Td,Pt) = the enhancement factor at the dew point temperature,

Td, and test pressure, Pt. (Since dew point is not known, this

equation is solved by iteration.)

e(Ts) = the SVP (ei or ew) at saturation temperature, Ts
Pt = the absolute test pressure, Pt
Ps = the absolute saturation pressure, Ps.

Then dew point temperature relative to that vapor pressure is solved for as the inverse of the
SVP formula (see equation 1 section 1.2.2.1)

Td =

(8)

where ew(Td) = SVP over water at the dew point temperature, Td,

obtained from equation 7.

The 3900 generates a particular dew point by first selecting a suitable saturation temperature,

Ts, then determining the saturation pressure, Ps, required to establish the correct dew point

vapor pressure (and ultimately the correct dew point temperature) at any given test pressure,

Pt. Dew point is independent of test temperature.

1.2.2.5 Parts Per Million by Volume, PPMv

PPMv is a relationship between the number of molecules of water vapor to the number of

molecules of the dry carrier gas. In the two-temperature two-pressure generator, it is
expressed by the relationship

PPMv =

(9)

where ƒ(Ts,Ps) = the enhancement factor at saturation temperature, Ts,

and saturation pressure, Ps
e(Ts) = the SVP (ei or ew) at saturation temperature, Ts
Ps = the absolute saturation pressure, Ps.

The 3900 generates a particular PPMv by first selecting an appropriate saturation
temperature, Ts, then determining the required saturation pressure, Ps. PPMv is independent
of test pressure and test temperature.

1-5

1.2.2.6 Parts Per Million by Weight, PPMw

MW

w

MW

a

∗

PPM

v

ƒ

(T

s

,Ps)

∗

e (

Ts)

P

t

ƒ

(T

t

,

Pt)

∗

e(

T

t

)P

s

∗

100

PPMw is a relationship between the weight of the molecules of water vapor to those of the

dry gas carrier. PPMw is related to PPMv by the relationship

PPMw =

(10)

where MWw = molecular weight of water (≈ 18.02 g/mol)
MWa = molecular weight of air (≈ 28.97 g/mol)
PPMv = Parts Per Million by Volume from equation 9.

Therefore PPMw ≈ 0.622 PPMv. With the exception of the 0.622 scaling factor, PPMw is
generated in a manner identical to that of PPMv. PPMw is also independent of test
temperature and test pressure. As shipped from the factory the default molecular weight of

the carrier gas is set at 28.9645 g/mol, appropriate for a carrier gas of air. To change the

molecular weight, consult the factory.

1.2.2.7 Relative Humidity, %RH

Relative Humidity, %RH, is a percentage ratio of the amount of water vapor in a given gas
mixture to the maximum amount physically allowable in the gas at the same temperature and
same pressure. As it relates to the two-temperature two-pressure generator, %RH is
expressed as

%RH =

(11)

where ƒ(Ts,Ps) = the enhancement factor at saturation temperature, Ts,

and saturation pressure, Ps

ƒ(Tt,Pt) = the enhancement factor at test temperature, Tt, and

test pressure, P

t

e(Ts) = the SVP (ei or ew) at saturation temperature, Ts
e(Tt) = the SVP (ei or ew) at test temperature, Tt
Pt = the absolute test pressure, Pt
Ps = the absolute saturation pressure, Ps

The 3900 generates a particular Relative Humidity by first selecting a suitable saturation
temperature, Ts, then determining the saturation pressure, Ps, required to establish the correct
%RH at test temperature, Tt, and test pressure, Pt. Relative Humidity is dependent on both
test temperature and test pressure.

The 3900 can display and generate %RH in either of two different methods. In the Normal
mode of RH calculation, saturation vapor pressure at the test temperature, e(Tt), is computed
with respect to water (equation 1) for test temperatures above 0 °C, and with respect to ice
(equation 2) for test temperatures below 0 °C. However, when configured for the WMO
mode of RH calculation (in accordance with the guidelines of the World Meteorological
Organization), the saturation vapor pressure at the test temperature, e(Tt), is always computed
with respect to water (equation 1) for all test temperatures, even those below 0 °C. Note that
the two methods are identical when the test temperature is above 0 °C, and only differ from
each other when the test temperature is below 0 °C. The method of RH calculation used by
the 3900 is user selectable. See section 3.3.

1-6

1.3 SPECIFICATIONS

Frost / Dew Point Range: ----------------------------------------------------------- -95 to +10 °C
Frost / Dew Point Uncertainty: * ----------------------------------------- (-95 to -90 °C) 0.9 °C

--------------------------------------------------------------------------------- (-90 to -80 °C) 0.5 °C

--------------------------------------------------------------------------------- (-80 to -70 °C) 0.2 °C

---------------------------------------------------------------------------------- (-70 to 10 °C) 0.1 °C
Parts Per Million Range: --------------------------------------------------- 0.05 to 12000 PPMv
Relative Humidity Range: -------------------------------------------------------- 0.0002 to ~50%
Saturation Pressure Range: ------------------------------------------------- Ambient to 300 psiA
Saturation Pressure Uncertainty (10 - 50 psiA): * ----------------------------------- 0.05 psiA
Saturation Pressure Uncertainty (50 - 300 psiA): * ---------------------------------- 0.30 psiA
Saturation Temp Range: ------------------------------------------------------------- -80 to +12 °C
Saturation Temp Uncertainty: * ----------------------------------------------------------- 0.08 °C
Saturation Heating Rate: --------------------------------------------------- 2 minutes per °C Avg
Saturation Cooling Rate: -------------------------------------------------- 2 minutes per °C Avg
Test Pressure Range: --------------------------------------------------------- Ambient to 50 psiA
Test Pressure Uncertainty (10 - 50 psiA): * ------------------------------------------ 0.05 psiA
Test Pressure Range (Option): --------------------------------------------- Ambient to 150 psiA
Test Pressure Uncertainty (10 - 150 psiA) (Option): -------------------------------- 0.05 psiA
Test Temp Range: ------------------------------------------------------------------------ 0 to 50 °C
Test Temp Uncertainty: * ------------------------------------------------------------------ 0.08 °C
Display Resolution: ------------------------------------------------------------------------------ 0.01
Gas Flow Rate Range: -------------------------------------------------------------- 0.1 to 5 L/min
Gas Flow Rate Range (Option): ** --------------------------------------------- 0.5 to 10 L/min
Gas Flow Rate Resolution: ------------------------------------------------------------- 0.02 L/min
Gas Flow Rate Uncertainty: * ---------------------------------------------------------- 0.2 L/min
Gas Type: --------------------------------------------------------------------------- Air or Nitrogen
Gas Pressure Rating (MAWP): ---------------------------------------------------------- 350 psiG
Refrigeration: --------------------------------------- 1/3 HP R-134A & 1/3 HP R-23 in cascade
Heating: ------------------------------------------------------- Stainless Steel Immersion Heaters
Test Port: ------------------------------------------ 1/4 Inch Swagelok® Tube Fitting (6.35mm)
Physical Dimensions: ------------ 37.5” H x 23” W x 30” D (953mm x 584mm x 762mm)

* Represents an expanded uncertainty using a coverage factor, k=2, at an approximate level

of confidence of 95%.

1.3.1 Facility Requirements

Electrical Power: ------------------------------------------------ 200/240VAC @ 50/60 Hz, 10A
Gas Supply (External): -- 350 psiG @ 0.17 cfm (5 L/min) w/ambient pressure FP <-80 °C
Floor Space: ------------------------------------------------------------------------- 9 Ft2 (0.84 m2)

** Gas Supply (Option): 350 psiG @ 0.35 cfm (10 L/min) w/ambient pressure FP <-80 °C

1.3.2 Environmental

Operating Temperature: ----------------------------------------------------------- 15 °C to 30 °C
Storage Temperature: ---------------------------------------------------------------- 0 °C to 50 °C
Humidity: -------------------------------------------------------------- 5 to 95% Non-condensing

1-7

1.4 COMPUTER / CONTROL SYSTEM

1.4.1 General Description

The Computer Control System is embedded in the humidity generator. The computer
controls all aspects of the humidity generation process (i.e. controlling temperatures,
pressures, etc.) as well as performing all human interface functions of keypad input and
information display. The computer also controls printer operation and interfaces with an
external computer (optional) for bi-directional RS-232C communications.

The Computer Control System is considered a "single-point automation" unit, controlling the
functions of the humidity generator to bring it to any operator input setpoint. The computer
will always control the system at the most current setpoint that has been input, whether from
keypad input, or from external computer input through the RS-232C port. The Computer
Control System knows nothing of past or future setpoints, requiring the use of an external
computer if automated humidity profiling or sequencing is desired.

1.4.2 Computer / Control System Configuration

Reference Drawings 95D39903, 95D39904 & 905

The Computer Control System consists of the following key components:

1) Embedded Computer system, consisting of:
a) CPU card
b) 8 channel, 16 bit A/D converter card with signal conditioning
c) Memory Card
d) Liquid Crystal Display driver card
e) Solid State Relay Board

2) 256 x 128, backlit, dot matrix Liquid Crystal Display (LCD) module

3) 16 key front panel keypad

1.4.2.1 Central Processing Unit (CPU)

Reference Drawing 95D39903

The Central Processing Unit (CPU) consists of a microprocessor, along with all supporting
hardware required to interface with the other devices. During the humidity generation
process, the CPU executes programming designed to control the parameters needed to
generate humidity, such as pulsing heaters and operating valves. Virtually all functions of the
system are controlled by this CPU which is responsible for system timing, user interfacing,
information display, and parameter control.

The CPU also retrieves measured temperature and pressure data from the A/D, which it uses

to calculate frost point, dew point, parts per million by volume, parts per million by weight
and relative humidity. Once calculated, this and all other pertinent information is sent to the
Liquid Crystal Display for real time numeric display. At given (user definable) intervals, the
CPU also sends this data to the printer, if enabled, for hard copy output.

1-8

1.4.2.2 Liquid Crystal Display (LCD)

Reference Drawing 95S39913

The display incorporated into the 3900 low humidity generator is a backlit, 256 x 128, dot
matrix Liquid Crystal Display (LCD). It is used for the purpose of displaying system
information such as setpoints, measurements and any other information pertinent to the
operation of the 3900 humidity generator.

1.4.2.3 Liquid Crystal Display Driver

Reference Drawings 95D39904, 95S39913

The Liquid Crystal Display Driver card receives display commands and data from the Central
Processing Unit then converts these into the signals required to drive the Liquid Crystal
Display module. It also incorporates a voltage inversion circuit, which converts +5 VDC
input to a -21 VDC output required by the LCD module.

1.4.2.4 Keypad

Reference Drawings 95D39903, 95D39904

The 4 x 4 keypad is the human interface to the 3900 generator. From this keypad, the
operator will select modes of operation from the menus, enter humidity and temperature
setpoints for humidity generation, and perform any other interface functions where user input
is required. During operation, most of the screens will show four rectangular shaped blocks
at the right side of the display. These blocks correspond with the four blank keys on the left
side of the keypad, which will be used to perform certain functions within the program.

1.4.2.5 Memory Card

Reference Drawings 95D39903, 95D39904

The Memory Card contains EPROM and battery backed RAM. This memory contains all
program code and data required for operation of the generator. All programs are stored in
EPROM, while all factory and user editable parameters (such as Calibration Coefficients) are
stored in battery backed RAM.

1.4.2.6 Analog to Digital Converter (A/D)

Reference Drawings 95D39903, 95D39904

The Analog to Digital Converter card is a 16 bit analog to digital converter, with integral
signal conditioning. It is used to continuously measure thermistor resistances and pressure

transducer / flow meter voltages. Data obtained from the A/D board is sent to the CPU where
it is used in the control process. The A/D converter has a usable voltage range of 0 to +5

VDC.

1-9

1.5 ELECTRICAL SYSTEM

1.5.1 AC Power Distribution

Reference Drawings 95D39904, 95S39906 through 95S39909

The 3900 requires a single phase AC power source. From the primary power switch CBS1,
primary power is distributed to the refrigeration compressors, C1 and C2, through SSR8 and
SSR9, the saturator fluid heater H1 through SSR10; the fluid pump FP1 through SSR6; the
console fan CF1 through SSR7; and the DC power supplies PS1 and PS2.

1.5.2 Power Supply ±15, +5 VDC

Reference Drawings 95D39904, 95S39907 through 95S39913

The ±15 VDC portion of power supply PS1 provides power to the flow meter, the pressure

transducers, the A/D card, and the LCD backlight inverter board. The mass flow transducer
and the A/D card use ±15 VDC for their particular voltage requirements, while the pressure

transducers require +15 VDC and the LCD backlight inverter board requires -15 VDC.

The +5 VDC portion of power supply PS1 provides power to the computer system, the solid
state relay board and the terminal interface board.

1.5.3 Power Supply +24 VDC

Reference Drawings 95D39904, 95S39907 & 908, 95S39910 & 911

The +24 VDC power supply PS2 provides power for all solenoid valves as well as the stepper
motor drives SMD-1 and SMD-2.

1-10

1.5.4 Analog Inputs

The temperature, flow and pressure transducers are measured by the Analog to Digital
Converter. Each of these is discussed further in the following sections.

1.5.4.1 Temperature Measurement

Reference Drawing 95S39912, 95S39915 & 916

Two thermistors are used by the system for continuous real time temperature monitoring.

A 1KΩ thermistor probe, RTD1, is connected to channel 1 of the Analog Terminal Board,
ATB. It is used to measure and control the actual saturation temperature.

A 10KΩ thermistor probe, RTD2, is connected to channel 2 of the ATB. It is used to

measure the test temperature, which is utilized for calculation and control of various humidity
parameters, such as %RH. The computer senses that the probe is connected by monitoring
terminal A2 of TIB.

When the Test Temperature probe is connected, a logic low is transferred from pin 1 to pin 2
of the probe connector, CN2, then to terminal A2 of TIB. When disconnected, terminal A2 is
internally pulled high.

The thermistor temperatures are measured by the Analog to Digital Converter card (A/D)
with a resolution of approximately 0.01 °C/bit. Since the temperatures measured by the A/D

card are based on ideal R-T curves, further calibration to actual temperature values is
performed by the CPU prior to use or display (refer to 4.2.2 for calibration).

A reference resistor of approximately 10KΩ is connected to channel 3 of the ATB, and is

used to compensate for short and long term drift of the temperature measurement electronics
in the A/D circuitry. Deviations from the reference resistor's nominal value are used to
mathematically offset the measured values of the two thermistor probes.

1.5.4.2 Test Pressure Transducer

Reference Drawings 95S39912, 95S39915 & 916

The Test Pressure Transducer TR5 is powered by +15 VDC from the ±15 VDC power supply
PS1. The output, 0-5 VDC for 0 to full scale (typically 50 psiA), is connected to channel 7 of

the ATB for measurement by the A/D card. When connected this transducer continually

monitors the test or barometric pressure. The computer senses that the probe is connected by
monitoring terminal A3 of TIB. When the probe is connected, a logic low is transferred from
pin 1 to pin 2 of the probe connector, CN3, then to terminal A3 of TIB. When disconnected,
terminal A3 is internally pulled high.

1-11

1.5.4.3 Low Range Saturation Pressure Transducer

Reference Drawings 95S39912, 95S39915 & 916

The Low Range Saturation Pressure Transducer TR3 is powered by the ±15 VDC power
supply PS1, and has a measurement range of 0 to 50 psiA. This pressure transducer is
pneumatically connected to the saturator via a computer controlled solenoid valve SOL4 that
is only activated below 50 psiA to monitor saturation pressure. The output voltage, 0-5 VDC
for 0 to 50 psiA, is connected to channel 5 of the ATB for measurement by the A/D card.

1.5.4.4 High Range Saturation Pressure Transducer

Reference Drawings 95S39912, 95S39915 & 916

The High Range Saturation Pressure Transducer TR4 is powered by the ±15 VDC power
supply PS1, and has a measurement range of 0 to 300 psiA. This transducer is generally used
to measure saturation pressures above 50 psiA. Operation is identical to that of the test
pressure transducer described in section 1.5.4.3. The output voltage, 0-5 VDC for 0 to full
scale, is connected to channel 6 of the ATB for measurement by the A/D card.

1.5.4.5 Gas Supply Pressure Transducer

Reference Drawings 95S39912, 95S39915 & 916

The Gas Supply Transducer TR1 is powered by +15 VDC from the ±15 VDC power supply
PS1. The output is connected to channel 4 of the ATB for measurement by the A/D card.
This transducer monitors the regulated gas supply pressure.

1.5.4.6 Mass Flow Meter

Reference Drawings 95S39912, 95S39915 & 916

The mass flow meter TR2 is a thermal type transducer and is powered by the ±15 VDC
power supply PS1. The output of the transducer is 0-1 VDC for a mass flow rate of 0-2

L/min. The output voltage is connected to channel 0 of the ATB for measurement by the A/D

card.

1-12

1.5.5 Control Logic

All control is performed digitally at a logic level of 5 VDC. Activation of most devices is
accomplished by applying a logic low to the control input of the associated solid state relay or
other coupling device.

1.5.5.1 Gas Supply Solenoid Valve

Reference Drawings 95S39908, 95S39915 & 916

The Gas Supply Solenoid Valve SOL1 is activated (gas on) by applying a low from the CPU
(monitored at TIB terminal C5) to the optical input (-) side of SSR5 on the Solid State Relay
Board. Valve actuation voltage is 24 VDC.

1.5.5.2 Fluid Pump Purge Solenoid Valve

Reference Drawings 95S39908, 95S39915 & 916

The Fluid Pump Purge Solenoid Valve SOL2, when activated, allows a dry gas supply to be
vented into the pump motor housing area in an effort to keep this area free of ice build up
when operating at very cold temperatures. The valve is activated by applying a low from the
CPU (monitored at TIB terminal C4) to the optical input (-) side of SSR4 on the Solid State
Relay Board. Valve actuation voltage is 24 VDC. Adjust needle valve V5 to 1.0 liter per
minute if regulated pressure is changed.

1.5.5.3 Saturator Vent / Purge Solenoid Valve

Reference Drawings 95S39908, 95S39915 & 916

The Saturator Vent / Purge Solenoid Valve SOL3, when activated, allows the saturator

pressure to vent to ambient. This valve is activated when performing shutdown, clear and
purge procedures. The valve is activated by applying a low from the CPU (monitored at TIB
terminal C3) to the optical input (-) side of SSR3 on the Solid State Relay Board. Valve
actuation voltage is 24 VDC.

1.5.5.4 Pressure Select Solenoid Valve

Reference Drawings 95S39908, 95S39915 & 916

The Pressure Select Solenoid Valve SOL4, when activated, allows the generator to monitor
the saturator using the 50 psiA pressure transducer when the saturator is operating in the
ambient to 50 psiA range. The valve is activated by applying a low from the CPU (monitored
at TIB terminal C2) to the optical input (-) side of SSR2 on the Solid State Relay Board.
Valve actuation voltage is 24 VDC.

1-13

1.5.5.5 Saturator Refrigerant Solenoid Valve

Reference Drawings 95S39908, 95S39917

The Saturator Refrigerant Solenoid Valve SOL5, when activated, allows refrigerant to be
injected into the refrigeration evaporator EX1 to cool and control the temperature of the
saturator. Activation of this solenoid valve is accomplished by applying a low from the CPU
(monitored at TIB terminal C0) to the optical input (-) side of SSR0 on the Solid State Relay
Board. Saturation temperature is controlled through fixed frequency pulse width modulation
of SOL5. Valve actuation voltage is 24 VDC.

1.5.5.6 Saturator Inlet/Outlet Heater

Reference Drawing 95S39908

The Saturator Inlet/Outlet Heater H2 is a resistive heating element which keeps the inlet and

outlet tubing of the saturator slightly warmer than the saturator itself in order to limit
condensation in this area. Activation of this heater is accomplished by applying a low from
the CPU (monitored at TIB terminal C5) to the optical input (-) side of SSR5 on the Solid
State Relay Board. Heater drive voltage is 24 VDC.

1.5.5.7 Saturator Fluid Heater

Reference Drawings 95S39909, 95S39917

The Saturator Fluid Heater H1 is a resistive heating element, activated by a two-stage control
process. Heat limit switch HLS1 must be in the normally closed position, indicating that
saturator fluid temperature is within allowable limits (i.e. below 30 °C). Activation is then
accomplished by applying a low from TIB channel B5 to the optical input (-) side of SSR10.
Saturator heater temperature is controlled through fixed frequency pulse width modulation of
the heater power at the AC line voltage.

1.5.5.8 Saturator Fluid Circulation Pump

Reference Drawings 95S39908, 95S39917

The Saturator Fluid Circulation Pump FP1 is a centrifugal pump energized by applying a low
from the CPU (monitored at TIB terminal C6) to the optical input (-) side of SSR6 on the
Solid State Relay Board. The pump is powered at AC line voltage.

1.5.5.9 Saturator Refrigeration Compressors

Reference Drawings 95S39909, 95S39917

The R-134A Compressor, C1, is energized by applying a low from the CPU (monitored at
TIB terminal C6) to the optical input (-) side of SSR8. The R-23 Compressor, C2, is
energized by applying a low from the CPU (monitored at TIB terminal B6) to the optical
input (-) side of SSR9. Compressor C2 is not activated by the computer until compressor C1
has been on for several minutes. Both compressors are powered at AC line voltage.

1-14

1.5.5.10 Flow Control Valve

Reference Drawing 95S39910, 95S39915 & 916

The Flow Control Valve V1 is a bi-directional ball valve actuated by a gear reduced stepper
motor. The valve is driven indirectly via pulses from the CPU to TIB terminals B0 & B2,
which triggers stepper motor driver SMD-1. Pulses on channel B0 turn the valve clockwise,
while pulses on channel B2 turn the valve counter clockwise. The stepper motor driver is
powered from the 24 VDC power supply. Controlled by the CPU using feedback from the
mass flow sensor, the computer operated flow control valve allows the mass flow rate to be
controlled by varying the orifice of the flow control valve from nearly closed to fully open
depending upon the required mass flow rate. This valve also determines the direction of flow
for purge and generate modes. When in generate mode, flow control is accomplished in the
proper direction using one of the orifices. When in purge mode the other orifice is used
causing the gas to flow in a different direction. The central point between the two orifices is
the HOME or CENTER CLOSED position of the valve. The HOME position is sensed by a
low at TIB channel A0 resulting from the contact closure of limit switch SL1.

1.5.5.11 Expansion Valve

Reference Drawings 95S39911, 95S39915 & 916

The Expansion Valve V2, or saturation pressure control valve, is a bi-directional ball valve
actuated by a gear reduced stepper motor. The valve is driven indirectly via pulses from the
CPU to TIB terminals B1 & B3, which triggers stepper motor driver SMD-2. Pulses on
channel B1 turn the valve clockwise, while pulses on channel B3 turn the valve counter
clockwise. The stepper motor driver is powered from the 24 VDC power supply. Controlled
by the CPU using feedback from the saturator pressure transducers, the computer controlled
expansion valve allows the saturated high pressure air stream to be reduced to test pressure
by varying the orifice of the expansion valve from nearly closed to fully open depending upon
the required saturation pressure. This valve also determines the direction of flow for purge
and generate modes. When in generate mode, flow control is accomplished in the proper
direction using one of the orifices. When in purge mode the other orifice is used causing the
gas to flow in a different direction. The central point between the two orifices is the HOME
or CENTER CLOSED position of the valve. The HOME position is sensed by a low at TIB
channel A1 resulting from the contact closure of limit switch SL2.

1.5.5.12 Expansion Valve Heater

Reference Drawing 95S39908

The Expansion Valve Heater H3 is a series of heating elements which keep the outlet tubing
of the saturator warm in order to limit condensation at the expansion valve. Activation of
these heaters is accomplished by applying a low signal from the CPU (monitored at TIB
terminal C1) to the optical input (-) side of SSR1 on the Solid State Relay Board. Heater
drive voltage is 24 VDC.

1-15

1.6 PNEUMATIC SYSTEM

The pneumatic system of the Model 3900 is an open loop "two pressure" system. Dry, high
pressure, high purity gas is saturated with water vapor as it passes through the saturator
assembly, then reduced to test pressure. Once reduced to the test pressure the gas is sent to
the device under test and ultimately vented to the atmosphere.

Dry high purity gas, regulated at up to 350 psiG, is connected to the gas supply inlet. The gas
is filtered by a 7 micron filter LF1, then admitted through the supply pressure regulator REG

to the ON/OFF solenoid valve SOL1. This regulator is factory preset to 300 psiG. Regulated

pressure is measured by the supply pressure transducer TR1.

After pressure regulation, the gas flows from the mass flow transducer TR2 to the flow
control valve V1. The gas is admitted through valve V1 in one of two modes:

A) Generate Mode: (reference drawing 95S39915)

The gas flows from flow control valve V1 through the saturator and is saturated with water
vapor as the gas establishes thermal equilibrium with the saturator fluid. The saturation
pressure, Ps (TR3 or TR4), and saturation temperature, Ts (RTD1), of the gas are then
measured. Upon exiting the saturator, the saturated gas encounters the expansion valve V2
and the saturation pressure is reduced to test pressure. The gas stream enters the device under
test from the fitting located on counter top, at the desired humidity, given test pressure, Pt,
and test temperature, Tt, conditions. The gas exits the device under test and is then vented to
the atmosphere.

B) Purge Mode: (reference drawing 95S39916)

By reversing the normal path the gas follows in the generate mode, it is possible to purge the
system of any unwanted moisture. The gas flows from flow control valve V1 through valve

V2 to the saturator. The gas passes from the saturator to the vent / purge solenoid valve

SOL3 and out the saturator vent outlet.

1.7 FLUID SYSTEMS

1.7.1 Saturator Fluid System

Reference Drawing 95S39917

Temperature conditioning of the saturator employs a methanol fluid circulation system in
conjunction with a cascade refrigeration system. Methanol is circulated by a magnetically
coupled centrifugal pump FP1 at approximately two gallons per minute. The methanol is
piped from the circulation pump to the immersion heater H1, through the R-23 refrigerant
evaporator EX1 to the saturator fluid jacket. From the saturator fluid jacket the methanol is
piped back to the circulation pump completing the saturator fluid circuit. RT1 is a methanol
expansion tank.

1-16

1.8 REFRIGERATION

The Model 3900 utilizes a cascade refrigeration system to cool the fluid circulating in the
saturator assembly.

1.8.1 Saturator Refrigeration

Reference Drawing 95S39917

The saturator fluid system is cooled by two hermetic refrigeration systems in cascade. The
high stage refrigeration utilizes Refrigerant 134A. This refrigerant is compressed from a low­pressure vapor into a high-pressure vapor by compressor C1. The high-pressure vapor flows
to the air-cooled condenser CON1 where it is cooled to a high-pressure liquid as heat is
removed. The condensed refrigerant passes through the filter-drier FD1 to the thermostatic
expansion valve V3. Refrigerant is metered into the interstage cooler CON2, heat is
removed, and the heat laden vapor is piped back to the compressor and the cycle is repeated.

The low stage refrigeration system utilizes Refrigerant 23, which has a boiling point of

-81.4 °C. The refrigerant is compressed from a low-pressure vapor to a high-pressure vapor
by compressor C2. The high-pressure vapor flows through the oil separator OS1 to the
interstage cooler CON2 where heat is removed as it is cooled to a high-pressure liquid. Upon
demand, refrigerant is admitted through solenoid valve SOL5 to the capillary tube where it is
metered into the saturator fluid heat exchanger/R-23 evaporator EX1. The refrigerant
expands and changes to a low-pressure vapor as it absorbs heat from the saturator fluid
circuit. The vapor is then piped back to the suction side of the compressor and the cycle is
repeated.

1-17

Section 2

INSTALLATION

2.1 GENERAL

Preparations should be made to have adequate floor space, proper power source, and a dry
gas supply available at the location of installation.

2.2 FACILITIES REQUIRED

Reference Drawing 94D39901

2.2.1 Floor Space

A minimum 9 ft2 (0.84 m2) of floor space is recommended for the 3900. This allows 6
inches (0.15 m) of access to side and rear console panels.

2.2.2 Power

The 3900 humidity generator requires a single phase AC power source as indicated on the
identification label on the rear of the unit.

2.2.3 Gas Supply

The 3900 requires a gas supply that is clean, dry and oil free. Zero nitrogen or air regulated
to a pressure between 325 and 350 psiG (≈ 22 to 24 bar gauge), with a flow rate capability of
5 standard liters/minute, and an ambient pressure frost point of -80 °C or lower is
recommended.

2.3 PREPARATION

Reference Drawing 95D39902

Temperature conditioning of the 3900's saturator employs a fluid circulation system in
conjunction with a cascade refrigeration system. Methyl alcohol (methanol) is used as the
heat transfer medium in this fluid circulation system because of its low freezing point
(-93 °C). The methanol has been drained prior to shipment and must be replaced prior to
power-up and operation. Extreme caution is required in the filling due to the flammability of
methanol.

2-1

2.3.1 Methanol Filling Procedure

Reference Drawing 08D39922

Equipment Required:

1. 1.5 gallons (5.675 Liters) of anhydrous methanol

2. 7/8" (23 mm) socket with 6" (0.15 m) extension

3. 3/16" (4.5 mm) ball/hex driver (to remove counter top bolts)

4. 3/8" (9.5 mm) ball/hex driver (to remove Methanol Expansion Tank Fill Port Plug)

5. Funnel

6. Gloves and goggles

CAUTION!

METHANOL IS FLAMMABLE AND POISONOUS

Keep away from sparks, flames, or other ignition sources. Avoid
prolonged or repeated breathing of vapors or contact with skin. Do
not allow material to contaminate water sources.

To fill saturator fluid system, proceed as follows:

1) Ensure power source is not connected.

2) Remove left and right side console panels.

3) Using 3/16" ball/hex driver, remove 4 securing bolts near corners, and remove

counter top.

4) Locate and remove RTD access insulation. Using the 7/8" socket with 6" extension,

remove the Saturator Methanol Fill Port Cap from the top of the saturator.

5) Remove circular insulation and the Methanol Expansion Tank Fill Port Plug.

6) Insert the funnel into the Methanol Expansion Tank Fill Port. Slowly and carefully

fill the saturator assembly until methanol is observed just below the Saturator
Methanol Port Fitting located on top of the saturator (in the square insulation area).

Note - The methanol must be added slowly as it is being gravity fed

through 3/8" tubing between the methanol expansion tank
and the saturator. Do not allow funnel to fill.

Methanol degrades the urethane foam insulation; sponge

dry any methanol spilled during the filling operation!

7) Replace the saturator methanol port cap (tighten 1/4 turn past finger tight).

8) Replace methanol expansion tank fill port plug.

9) Replace all insulation.

10) Replace counter top and console panels.

2-2

2.3.2 Vent Muffler

Install vent muffler into gas vent port at rear of system.

2.4 POSITIONING & LEVELING

1) Position the system so as to have access to all sides of the console.

2) Lower leveling legs and raise the wheels off the floor to hold system stationary. Level
the console using counter top as a reference. Tighten leveling leg locking nuts against
frame.

2.5 FACILITY CONNECTIONS

Reference Drawing 94D39901

2.5.1 Gas Supply

1) Connect a source of clean, oil free, gas to "GAS INLET" with a line size equal to or
larger than the 1/4" OD tubing on console. The gas supply should be regulated to a
pressure between 325 and 350 psiG (Maximum Allowable Working Pressure is 350
psiG).

2.5.2 Pressure Vent

No connection is required. Normally a sintered filter is installed. A small tray should be
placed under the vent to catch drips of water.

CAUTION!

Do not restrict or back-pressure the gas vent in any way.

2.5.3 AC Power

1) Connect to a source of single phase AC power per specifications on the identification
label on the rear of the unit.

2-3

Section 3

SetPnt Actual

*FRST PT oC -10.00

CHNG

EDIT

PRG

GEN

Control Parameters

Supply Pressure Indication

Date and Time

Function Key

Labels

Asterisk Indicates

Active Control

Parameter

{

}

OPERATION

3.1 GENERAL

At this point, all preparation and positioning of the Model 3900 humidity generator should have
been performed. Refer to section 2.

3.2 STANDARD OPERATING PROCEDURES

3.2.1 Power-Up

1) Verify that the gas supply connection has been made and the gas supply is pressurized.
Open any On/Off valve in the supply line if applicable.

2) Verify that primary AC power is connected to the console and is switched ON.

3) Toggle the Power switch located at rear console panel to ON. Within a few seconds, the
liquid crystal display will light, a banner will appear, and the generator will perform a
very short diagnostics test.

3.2.2 Control/Display Screen

At the end of the power-up sequence, the following Control/Display Screen appears.

All control and measurement parameters critical to the operation of the humidity generator are
displayed on this screen. Notice that in the leftmost column, each parameter is identified with a
brief title and corresponding units. The asterisk in the leftmost column indicates the active
humidity control parameter (section 3.2.4).

DEW PT oC -11.23
PPMv 2581.
PPMw 1605.
%RH 10.37
SATUR psi 70.92
SATUR
TEST psi
TEST
FLOW l/m 1.000

03/25/11 15:23:03 [294.6]

o

C 10.00

o

C

3-1

SETP

/CAL

The Date and Time are displayed at the bottom of the screen, updating continuously every few
seconds. To the right of the Date and Time is a number enclosed in square brackets [ ]. This is
a measurement of the regulated input supply pressure.

SetPnt column lists the user entered (and system calculated) control setpoints. The 3900

The
uses the setpoints as target values when controlling these parameters. The setpoints may be
changed by the user at will (section 3.2.3).

The Actual column lists all of the measured data and calculated parameters of the generator.

A description of each of the Control/Display parameters follows:

Parameter Description

FRST PT oC - The Frost Point temperature calculated at test pressure, P

temperature, T

, and saturation pressure, Ps. This calculation is independent of

s

, from saturation

t

test temperature, and is only valid when below 0.01 °C Frost Point. Although
inter-related, Frost Point is not the same as Dew Point.

DEW PT�oC - The Dew Point temperature calculated at test pressure, Pt, from saturation

temperature, Ts, and saturation pressure, Ps. This calculation is valid both
above and below 0 °C, and is independent of test temperature. While inter­related, Dew Point is not the same as Frost Point.

PPMv - Parts Per Million by Volume, PPMv, calculated from saturation temperature,

Ts, and saturation pressure, Ps. This calculation is independent of test
temperature and test pressure.

PPMw - Parts per Million by Weight, PPMw, calculated from saturation temperature,

Ts, saturation pressure, Ps, and the molecular weight of the carrier gas. To
change the molecular weight of the carrier gas, refer to section 3.3. This
calculation is independent of test temperature and test pressure.

%RH - The %RH calculated from saturation pressure, P

, saturation temperature, Ts, at

s

test pressure, Pt, and test temperature, Tt. This calculation is only accurate if the
device under test is at the conditions indicated by the test temperature and test
pressure probes. Placing these external probes at the humidity sensing point of
devices under test gives the actual value of the relative humidity being imposed
on the devices, as %RH is dependent on both test pressure and test temperature.

SATUR psi - The saturation pressure measurement, Ps, in pounds per square inch absolute, as

measured by the low or high range saturation pressure transducer. (Pressure
units may be set to psi, bar, or hPa. See section 3.3) Various humidity values
are generated by controlling the saturation pressure, relative to a constant
saturation temperature, Ts. Saturation pressure is used in the calculation of all
humidity parameters.

SATUR oC - The temperature of saturation, T

, as measured by the saturation fluid

s

temperature probe. This is used to control the temperature of the fluid
surrounding the saturator, thereby ultimately controlling the saturation
temperature. Saturation temperature is used in the calculation of all humidity
parameters.

3-2

TEST psi - The test pressure, P

, in pounds per square inch absolute, measured whenever

t

the test pressure transducer is plugged in. (Pressure units may be set to psi, bar,
or hPa. See section 3.3) Since test pressure is used in the determination of
Frost Point, Dew Point, and %RH, the test pressure transducer should be placed
as close as possible to, but downstream of, the device under test in order to
measure device pressure. When the test pressure transducer is not plugged in,
calculations of Frost Point, Dew Point, and %RH are referenced to the user
entered test pressure setpoint rather than any measured value. For accurate
humidity generation under these conditions, the absolute pressure at the device
under test should be entered as the test pressure setpoint.

TEST oC - The test temperature, T

, as measured by the test temperature probe whenever

t

the test temperature probe is plugged in. Since test temperature is used in the
calculation of %RH, the test temperature probe should be placed as close as
possible to either the temperature sensing element (for chilled mirror
hygrometers, etc.) or the humidity sensing element (for solid state humidity
sensors) of any device under test. When the test temperature probe is not
plugged in, calculations of %RH are referenced to the user entered test
temperature setpoint rather than any measured value. For accurate humidity
generation under these conditions, the temperature at the device under test
should be entered as the test temperature setpoint.

FLOW l/m - The mass flow rate, in standard liters per minute. Flow rate is not used in the

calculation of humidity and is only an indication of the amount of gas flowing
into the system. Since all gas flowing into the system also flows through and
out of the system, it is useful for setting the desired flow rate through a device
under test.

3.2.2.1 Changing the Display Contrast

To increase the display contrast press the <1> key on the numeric keypad. To decrease the
contrast, press the <0>. The new contrast setting is automatically remembered by the system.

3-3

3.2.3 Changing Setpoints

SetPnt Actual

*FRST PT oC -1_0.00

Key Labels

Function

Keys

SetPnt Actual

*FRST PT oC -10.00

CHNG

EDIT

PRG

GEN

After the initial power-up sequence of section 3.2.1, the Control/Display screen appears. On the
display are four rectangular function key labels. These labels correspond to the four blank keys
on their right.

To change any of the Frost Point, Dew Point, PPMv, PPMw, %RH, pressure, temperature, or
flow setpoints, press the [CHNG SETP] key. The menu labels then change to arrows.

A cursor block will begin flashing in the
humidity control parameter (the one with the asterisk to the left). Move the cursor up, down,
left, or right using the appropriate arrow key.

To change any (or all) of the setpoints, position the cursor over the desired setpoint, then edit the
value using the numeric keypad. Continue using the arrow keys and the numeric keypad until all
desired values have been changed.

To enter a negative setpoint value for Frost Point, Dew Point, or Saturation Temperature, place
the cursor on the leftmost digit of the desired setpoint and press the left arrow key to toggle the
minus sign on and off.

End the setpoint editing session by pressing the <ENTER> key on the numeric keypad. The
arrow keys revert back to their previously displayed functions, and the setpoints are validated
and updated.

DEW PT oC -11.23
PPMv 2581.
PPMw 1605.
%RH 10.37
SATUR psi 70.92
SATUR oC 10.00
TEST psi
TEST
FLOW l/m 1.000

03/25/11 15:23:03 [294.6]

o

C

DEW PT oC -11.23
PPMv 2581.
PPMw 1605.
%RH 10.37
SATUR psi 70.92
SATUR
TEST psi 14 70
TEST
FLOW l/m 1.000

03/25/11 15:23:03 [294.6]

o

C 10.00

o

C 21 11

SetPnt column on the first digit of the current

SETP

/CAL

3-4

3.2.3.1 Example Setpoint Change

SetPnt Actual

*FRST PT oC -20.00

SetPnt Actual

*FRST PT oC -20_.00

SetPnt Actual

*FRST PT oC -1_0.00

Change the setpoints to -20 °C Frost Point at a flow rate of 0.50 L/min.

1) Press [CHNG SETP]. The key labels change to arrows, and the cursor begins flashing.

DEW PT oC -11.23
PPMv 2581.
PPMw 1605.
%RH 10.37
SATUR psi 70.92
SATUR
TEST psi 14 70
TEST
FLOW l/m 1.000

03/25/11 15:23:03 [294.6]

o

C 10.00

o

C 21 11

2) Using the arrow keys and numeric keys as necessary, make the
value on the screen appear as

-20.00.

FRST PT oC setpoint

DEW PT oC -11.23
PPMv 2581.
PPMw 1605.
%RH 10.37
SATUR psi 70.92
SATUR oC 10.00
TEST psi 14 70
TEST
FLOW l/m 1.000

03/25/11 15:23:03 [294.6]

o

C 21 11

3) If the negative sign is not present, use the arrow keys to place the cursor on the leftmost
digit of the

FRST PT oC setpoint and press the left arrow key once. The negative sign

will appear.

4) Move the cursor down to the FLOW l/m setpoint value.

DEW PT oC -11.23
PPMv 2581.
PPMw 1605.
%RH 10.37
SATUR psi 70.92
SATUR
TEST psi 14 70
TEST
FLOW l/m 1_.000

03/25/11 15:23:03 [294.6]

o

C 10.00

o

C 21 11

3-5

5) Using the arrows and numeric keys as necessary, make the

SetPnt Actual

*FRST PT oC -20.00

FLOW l/m setpoint value

appear as 0.500.

DEW PT oC -11.23
PPMv 2581.
PPMw 1605.
%RH 10.37
SATUR psi 70.92
SATUR oC 10.00
TEST psi 14 70
TEST
FLOW l/m 0_.500

03/25/11 15:23:03 [294.6]

o

C 21 11

6) Find the asterisk in the left most column of the display. If it is not next to the

FRST PT oC label, use the arrow keys and position the cursor back at the FRST PT oC

setpoint value. This tells the system to switch to Frost Point Control mode (see section

3.2.4).

7) Press the <ENTER> key. The cursor disappears, and the displayed function key labels
revert back to their previous descriptions. There should also be an asterisk left of

FRST PT oC to indicate that it is the humidity controlling parameter.

Setpoints within legal limits are accepted. Those setpoints that are slightly above or below these
limits are simply replaced by the appropriate limit value. Those setpoints that are far beyond the
limits revert back to the previous setpoint value and are accompanied by a short audible warning
beep. This most often occurs when the user inadvertently enters a wrong value or fails to include
a decimal point.

The system automatically chooses a suitable saturation temperature setpoint if the one displayed
would require a saturation pressure outside the range of the systems capability. In other words,
if the value of the current control parameter requires a saturation pressure that is either too high
or too low to achieve, the saturation temperature is automatically adjusted to a new value that
allows saturation pressure to work within normal limits. The resulting humidity output will be
valid regardless of the saturation temperature and saturation pressure combination that the system
chooses.

3-6

3.2.4 Control Modes

The generator has the ability to control the humidity in one of six possible modes.

Mode 0

Power -up pressure, P
Default T

*FRST PT oC is controlled at a constant value by varying the saturation

, to compensate for changes in either saturation temperature,

, or test pressure, Pt. While Frost Point is held constant, PPMv, PPMw,

s

s

and %RH may vary. When in Frost Point control mode, the saturation
temperature setpoint is automatically determined.

Frost Point control mode is the one most often used, and is the power-up

default mode of the generator. Frost Point control mode will automatically
change to Dew Point control mode for setpoints above 0.01 °C.

Frost Point is independent of test temperature.

Mode 1 *DEW PT

o

C is controlled at a constant value by varying saturation pressure,

Ps, to compensate for any changes in either saturation temperature, Ts, or test
pressure, Pt. While Dew Point is held constant, PPMv, PPMw, and %RH
may vary. While in Dew Point control mode, the saturation temperature
setpoint is automatically determined.

Dew Point control mode is valid both above and below 0 °C.

Dew Point is independent of test temperature.

Mode 2 *PPMv is controlled at a constant value by varying saturation pressure, Ps, to

compensate for any changes in saturation temperature, Ts. While PPMv is
held constant, Frost Point, Dew Point, and %RH may vary. While in PPMv
control mode, the saturation temperature setpoint is automatically determined.

PPMv is independent of test pressure and test temperature.

Mode 3 *PPMw is controlled at a constant value by varying saturation pressure, Ps, to

compensate for any changes in saturation temperature, Ts. While PPMw is
held constant, Frost Point, Dew Point, and %RH may vary. While in PPMw
control mode, the saturation temperature setpoint is automatically determined.

PPMw is independent of test pressure and test temperature.

Mode 4 *%RH is controlled at a constant value by varying saturation pressure, Ps, to

compensate for any changes in saturation temperature, Ts, test temperature,
Tt, or test pressure, Pt. While %RH is held constant, all other humidity
parameters may vary. While in %RH control mode, the saturation
temperature setpoint is automatically determined.

Mode 5

*SATUR psi , P

, is controlled at a constant value independent of any other

s

pressure, temperature, or humidity value. While saturator pressure is held
constant, all humidity parameters may vary. While in saturation pressure
control mode, the saturation temperature remains fixed at the user entered
setpoint.

3-7

3.2.4.1 Changing Control Mode

SetPnt Actual

*FRST PT oC -10.00

SetPnt Actual

*FRST PT oC -10.00

SetPnt Actual

*FRST PT oC -1_0.00

1) Get into the setpoint editing mode by pressing [CHNG SETP]. The key labels change to
arrows.

DEW PT oC -11.23
PPMv 2581.
PPMw 1605.
%RH 10.37
SATUR psi 70.92
SATUR
TEST psi 14 70
TEST
FLOW l/m 1.000

03/25/11 15:23:03 [294.6]

o

C 10.00

o

C 21 11

2) Position the cursor on the desired control parameter.

DEW PT oC -11.23
PPMv 2_581.
PPMw 1605.
%RH 10.37
SATUR psi 70.92
SATUR oC 10.00
TEST psi 14 70
TEST
FLOW l/m 1.000

03/25/11 15:23:03 [294.6]

o

C 21 11

3) Change its value if needed.

DEW PT oC -11.23
PPMv 2000._
PPMw 1605.
%RH 10.37
SATUR psi 70.92
SATUR
TEST psi 14 70
TEST
FLOW l/m 1.000

03/25/11 15:23:03 [294.6]

o

C 10.00

o

C 21 11

3-8

SetPnt Actual

FRST PT oC -10.00

4) With the cursor still on that parameter, press <ENTER>. The asterisk will then appear

next to this selected control mode parameter.

DEW PT oC -11.23
*PPMv 2000.
PPMw 1244.
%RH 8.051
SATUR psi 91.08
SATUR oC 10.00
TEST psi 14 70
TEST
FLOW l/m 1.000

03/25/11 15:23:33 [294.6]

o

C 21 11

When <ENTER> is pressed, the system first determines if there is a requested control mode
change based on the position of the cursor. If the cursor is on one of the first six parameters, the
control mode is changed to that parameter; otherwise the previous control mode remains in
effect.

Next the setpoint of the active control mode is read and validated. Finally, the remaining
parameters (Test Temperature, Test Pressure, and Flow) are read and validated. The current
control mode parameter is indicated with an asterisk to its left.

3-9

3.2.5 Purging

The Purge mode is generally used to prevent icing within the saturator and dry the saturator
outlet after movement (transportation), storage (power off, no gas flow, etc.), after performing
the saturator fill procedure (section 3.2.8), or while transitioning the saturator from higher to
lower temperatures.

When the system is not being used (power off, no gas flow, etc.), the saturator is closed off and
the gas within is static. As thermal equilibrium is reached, water vapor will condense on all
inner surfaces between the saturator outlet and the expansion valve inlet. The Purge mode
counteracts this condition by allowing the carrier gas to flow in the opposite direction (expansion
valve to saturator), drying the affected sections of tubing. This is a necessary preparatory step in
any low humidity system.

As a general rule, when starting from an ambient condition the system should be purged for 24
hours or more before attempting to operate in the Generate mode. If sufficient purge time is not
allowed, condensed or trapped water will remain and system accuracy will suffer. Insufficient
purge time is usually indicated by higher than normal (wetter than normal) indications of the
device under test. These indications can be as little as a few tenths of a degree to as much as
several degrees frost point.

Purging should also be performed while transitioning from warmer to colder saturation
temperatures, and for approximately 5 hours after each 500 hours of continuous Generate mode
operation.

During Purge mode, both flow control and saturation temperature control are active, but
saturation pressure control is disabled. The generator will attempt to achieve the indicated flow
and saturation temperature setpoint values.

Notes -1) When the saturation temperature is lowered, the fluid jacket

surrounding the saturator cools in order to reduce the saturation
temperature to its new setpoint value. As the saturator cools during
this transition period, temperature gradients will exist between the
inside of the saturator and the fluid jacket that surrounds it. The
saturator outlet passes through this fluid jacket and will also exhibit
temperature gradients along its length. If gas is allowed to flow
normally through the saturator during this cooling period, the
100% humidified gas of the saturator may condense at the colder
saturator outlet. Therefore, Purge mode should be used while
cooling the saturator to lower temperatures. For this reason, the
lowest humidity of a generation sequence or profile should be
performed first. This low to high order requires that a Purge be
performed only once prior to the generation sequence when cooling
to the lowest saturation temperature. Then as humidity values are
increased, warming the saturator to higher values, further purging
is not required.

2) During Purge, no gas flows to the 3900 Conditioned Gas Outlet,
and consequently no gas flows through the device under test if
connected.

3-10

3.2.5.1 Purge Procedure

SetPnt Actual

*FRST PT oC -10.00

CHNG

CLR

PRG*

1) From the idle Control/Display screen press [PRG]. The pump and compressors start and
purge gas begins flowing within several seconds. Or, if the system is currently running in
the Generate mode, press [PRG GEN*] to switch to Purge mode. Within a few seconds,
the following screen appears.

2) Using the [CHNG SETP] key, adjust setpoints to desired settings.

3) Remain in the Purge mode for 24 to 48 hours if possible, depending on (1) flow rate, (2)

Notes -1. Entering a humidity control setpoint value causes the generator to automatically

DEW PT oC -11.23
PPMv 2581.
PPMw 1605.
%RH 10.39
SATUR psi 70.29 14.48
SATUR oC 10.00 10.00
TEST psi 14.70
TEST
FLOW l/m 1.000 1.001

03/25/11 15:23:37 [294.6]

o

C 21.10

SETP

GEN

STOP

A) Typical purge flow rate is 1 liter/minute. Lower flows (minimum 0.1 L/min) will

conserve gas while higher flow rates (maximum 5 L/min) will decrease purge time.

B) Saturation temperature should be set to the lowest temperature desired in the

humidity generation sequence. However, when starting from a power-on condition,
allow the generator to purge at the default setpoint (10 °C) for several hours before
adjusting the setpoint to a lower value. The higher the saturation temperature during
purge, the quicker the system will dry down. This makes it easier to evaporate any
condensate that may exist in the saturator outlet tubing.

To change the saturation temperature setpoint, edit one of the humidity control

setpoints to a desired minimum target value. The saturation temperature setpoint will
automatically adjust. (See note 1.)

how low the saturation temperature setpoint is, and (3) the length of time that the system
purged while at a higher saturation temperature (discussed in step 2B above). Lower
flow rates and lower saturation temperatures require longest purge times.

determine a suitable saturation temperature for that humidity. Saturation temperature
setpoint must always be at least 2 °C above the frost point setpoint, and in general will
not be more than 20 to 30 °C above frost point setpoint. If an attempt is made to
directly adjust the saturation temperature setpoint outside these bounds, it will
automatically readjust to a suitable value for the setpoint of the current humidity
control parameter.

2. When in the Purge mode, if the flow rate will not achieve setpoint or drops to zero,
icing may have occurred within the saturator passages, the saturator vent, or at the
saturator inlet causing the generator to shutdown due to Error 4 - Low Supply
Pressure. If this condition occurs, restart the generator, adjust the mass flow setpoint
to zero, adjust the saturation temperature setpoint to 5 °C or warmer and allow to
stabilize. Perform the Saturator Clear procedure (Section 3.2.6), then readjust
setpoints and continue in the Purge mode.

3-11

3.2.6 Saturator Clear

SetPnt Actual

*FRST PT oC -10.00

CHNG

CLR

PRG*

This procedure is used to clear the saturator of any excess water that may have occurred as a
result of filling (see section 3.2.8), as a result of movement (such as transportation), or as a result
of freezing and thawing a full saturator. Any time that water is observed at the gas vent whether
after filling, movement, or thawing, the saturator should be cleared several times until no further
indication of excess water exists.

If the saturator has not been recently filled, and the generator not moved, saturator clearing is
normally not needed (although it can never hurt).

3.2.6.1 Saturator Clear Procedure

1) From the Control / Display screen press [PRG] to enable the purge mode. The pump and
compressors start and purge gas begins flowing within several seconds.

Or, if the system is currently running in the Generate mode, press [PRG GEN*] to

switch to Purge mode.

2) View the saturator temperature. If the generator is or has been operating below 0 °C,
adjust the Dew Point setpoint to 2 °C or warmer. Then adjust the saturation temperature
setpoint to 5 °C or warmer and allow the system to stabilize.

Note - The saturation temperature must be above 0 °C for a

minimum of four hours before proceeding with the saturator
clear procedure. This allows any ice in the saturator to
completely melt.

3) Press [CLR] key 3 times. The key will increment to [CLR 15]. This clears the saturator
of excess water for 15 cycles by pressurizing the system at 1 liter/minute and then
quickly depressurizing the system through the gas vent at the rear of the generator. This
will occur 15 times, decrementing the number on the [CLR] key after each cycle.

4) If water is still observed at the pressure vent port by the fifteenth cycle, press the [CLR]
key again for more cycles. Each time the [CLR] key is pressed, 5 cycles are added.
Repeat this step until all excess water has been cleared. (Pressing the <0> key on the
numeric keypad aborts the clearing process, removing the number from the [CLR] key
label.)

Upon completion of the Saturator Clear process, the system remains in the Purge mode at the
flow rate indicated in the

DEW PT oC -11.23
PPMv 2581.
PPMw 1605.
%RH 10.39
SATUR psi 70.29 24.35
SATUR oC 10.00 10.00
TEST psi 14.70
TEST
FLOW l/m 1.000 1.001

03/25/11 15:23:39 [294.6]

SetPnt column.

o

C 21.10

3-12

SETP

[15]

GEN

STOP

3.2.7 Generating

SetPnt Actual

*FRST PT oC -10.00 -10.02

CHNG

PRNT

PRG

The Generate mode is used to generate a gas stream of desired humidity. In the Generate mode,
the gas flows through the saturator where it is saturated with water vapor at the indicated
saturation temperature and saturation pressure conditions, then flows to the device under test at
test pressure and test temperature conditions. Before attempting to Generate, the Purge
procedure (Section 3.2.5) should have been performed.

Notes

- 1. Upon initial receipt of the generator prior to use for the very
first time, a Saturator Fill procedure (section 3.2.8 should be
performed.)

2. Before attempting to Generate after periods of inactivity, the
Purge procedure (section 3.2.5) must be performed and allowed to
purge for 24 to 48 hours.

3. When in the Generate mode, if the flow rate indicates zero or
remains well below setpoint, icing has occurred at the saturator
outlet. This condition can occur after a saturator fill if an
insufficient saturator clear and/or purge was performed. If this
condition occurs, the saturator must be warmed above freezing (in
the Purge mode) until the problem corrects itself. The Purge
procedure (section 3.2.5) and the Saturator Clear procedure
(section 3.2.6) must be performed.

When the [GEN] key is pressed (or the [PRG* GEN] key from within the Purge mode), the
temperature, pressure, and flow control processes begin. The fluid circulation pump will start
and the refrigeration system will begin its start up sequence. If switching to Generate from the
Purge mode, all control processes were already active with the exception of pressure control.

When in Generate mode, the 3900 will control at the values of humidity, temperature, and flow
indicated in the

SetPnt column. Setpoints may be freely changed regardless of whether the

system is Generating, Purging, or Stopped. The values in the Actual column are the actual
measured values, and when Generating will update approximately every 2 seconds.

The [PRNT] key is used to activate/deactivate the printer (see section 3.2.12).

The [PRG GEN] key is used to switch back and forth between Generate and Purge modes.

Pressing [STOP] causes the computer to perform a system shutdown (see section 3.2.9).

DEW PT oC -11.23 -11.25
PPMv 2581. 2576.
PPMw 1605. 1603.
%RH 10.39 10.36
SATUR psi 70.29 70.42
SATUR
TEST psi 14.70
TEST
FLOW l/m 0.200 0.205

03/25/11 15:23:40 [294.6]

o

C 10.00 10.00

o

C 21.10

3-13

SETP

GEN*

STOP

3.2.7.1 Generating Procedure

SetPnt Actual

*FRST PT oC -10.00 -10.02

CHNG

PRNT

PRG

Note

- Before attempting to Generate after periods of inactivity, the Purge
procedure (section 3.2.5) must be performed and allowed to purge
for 24 to 48 hours.

To operate the system in the Generate mode:

1) Enter the desired setpoints (section 3.2.3) and set the control mode (section 3.2.4).

2) From an idle mode press [GEN]. Or, from the Purge mode, press [PRG* GEN].
Within a few seconds, the following screen appears.

DEW PT oC -11.23 -11.25
PPMv 2581. 2576.
PPMw 1605. 1603.
%RH 10.39 10.36
SATUR psi 70.29 70.42
SATUR oC 10.00 10.00
TEST psi 14.70
TEST
FLOW l/m 0.500 0.505

03/25/11 15:23:41 [294.6]

o

C 21.10

SETP

GEN*

STOP

3) Allow the system to run overnight if possible.

- Even though the greatest portion of excess moisture is removed with

Note

the purge procedures, an accurate humidity point may still take
several hours to achieve, especially when attempting to generate
very low humidities. For instance, a -80 °C frost point temperature
can typically take 24 hours or more to completely dry down the
outlet tubing and the device under test.

4) After operating in the Generate mode for several hours, the system should be at the
desired humidity point. Check all instrumentation for stability and record a data point.

5) Adjust humidity to the next desired setpoint. Several hours should be allowed for the
system and instrumentation being calibrated to stabilize and equilibrate to the new
humidity value.

6) After the required amount of time, check all instrumentation for stability and record the
data point.

7) Repeat steps 5 and 6 as required.

3-14

3.2.7.2 Example Instrument Set-Up

A chilled mirror hygrometer is to receive dew/frost point calibration at ambient temperature and
pressure conditions.

1) Connect the gas inlet side of the chilled mirror to the generator outlet fitting with polished

ID stainless steel tubing. The generator outlet is the Swagelok

®

fitting located on the
counter top farthest from the front of the generator. For best chilled mirror stability,
insulate this tube.

2) Allow the chilled mirror outlet to exhaust to atmosphere through a short section of
tubing. This helps to prevent upstream humidity permeation.

3) Connect the pressure transducer to mirror exhaust if other than atmospheric pressure.
Ensure that the transducer is plugged into the 3900. Otherwise, enter the mirror pressure
as the Test Pressure Setpoint.

4) If making relative humidity measurements, plug the Test Temperature probe into the
3900 and attach the probe to the mirror thermometer.

3-15

3.2.8 Saturator Fill

SetPnt Actual

*FRST PT oC -10.00

CHNG

CLR

PRG*

The saturator filling procedure should be performed upon initial use after installation, and
approximately every 500 hours or more of operation thereafter, depending upon the humidities
and flow rates generated. Generating high flow rates and high humidity values requires more
frequent filling.

The generator may require up to ten ounces (300 cc) of pure water (triple distilled or better) per
fill. The amount of run time available from each fill is dependent upon the Frost/Dew Point
being generated (during a Purge, it is based upon the saturation temperature). Colder
temperatures (lower humidities) require less water than do higher temperatures (higher
humidities).

The following table illustrates the approximate run time available at various generated humidity
values. The amount of water used is also dependent upon flow rate. For instance, using only

0.5 liters/min gives twice as much run time as listed below, while using 2.0 liters/min gives only
one half as much run time as listed.

Dew/Frost Point Approximate Continuous
Generated Run Time @ 1 liter/min flow

+15 °C 400 hours (2 weeks)
+10 °C 500 hours (3 weeks)
0 °C 1000 hours (1.5 months)

-10 °C 2500 hours (3.5 months)

-30 °C 17,000 hours (2 years)

-50 °C 150,000 hours (17 years)

-70 °C 2,500,000 hours (285 years)

Even though the lower temperatures make it appear that the system would never require filling;
remember that a Purge always starts first at the higher temperatures to remove excess condensed
water within the saturator passages and outlet tubing. Under these circumstances, the saturator
water will eventually be depleted even if the lower temperatures are all that is ever generated.

3.2.8.1 Saturator Fill Procedure

1) Put the system in a Purge mode, using the [PRG] key if the system is idle, or the [PRG*
GEN] if currently in the Generate mode. Within a few seconds, the Purge screen
appears.

DEW PT oC -11.23
PPMv 2581.
PPMw 1605.
%RH 10.39
SATUR psi 70.29 14.60
SATUR oC 10.00 10.00
TEST psi 14.70
TEST
FLOW l/m 1.000 1.001

03/25/11 15:23:42 [294.6]

o

C 21.10

3-16

SETP

GEN

STOP

2) View the Saturation Temperature (

-

SetPnt Actual

*FRST PT oC -10.00

CHNG

CLR

PRG*

SATUR oC). If the Saturation Temperature Setpoint

is below 0 °C, then (1) adjust the dew point to 2 °C or warmer, and (2) adjust the
saturation temperature to 5 °C or warmer. Allow the Saturation Temperature to warm
above 0 °C and stabilize before proceeding to allow all ice in the saturator to completely
melt.

Note

Due to the large thermal mass of the saturator, the saturation
temperature must be above 0 °C for a minimum of four hours
before proceeding with the saturator fill procedure. This allows for
sufficient thermal lag time when undergoing an ice/water phase
change within the saturator.

3) Press the [CLR] key. The key will increment to [CLR 10]. This step will perform 10

cycles of a pressurization/depressurization process which clears excess water from the
pressure vent tubing and lower portions of the saturator prior to performing a saturator
fill. Excess water is cleared by pressurizing the saturator at 1 liter/minute and then
quickly depressurizing the saturator through the gas vent at the lower rear of the
generator.

4) After the completion of the Clear cycles, adjust flow setpoint to 0.5 liters/minute or less.

5) Locate the saturator fill port at front right of counter top and remove the port cap.

6) Slowly add two ounces of pure water (triple distilled or reagent grade) into the fill port

using the supplied funnel.

7) Replace the port cap and tighten port cap 1/4 turn past finger tight.

8) Press saturator [CLR] key 2 times to increment the saturator clear counter to [CLR 20].

This clears the saturator of excess water for 20 cycles.

9) If water is not observed in the gas vent during the 20 cycles repeat steps 4-8. Continue

repeating steps 4-8 until water is observed in the gas vent. Saturator capacity is
approximately 10 ounces (300 cc).

10) If water is observed in the gas vent after the twentieth cycle, press the [CLR] key for

more cycles. Each time the [CLR] key is pressed, 10 cycles are added. Repeat this step
until all excess water has been cleared.

11) Adjust flow setpoint to 1.0 liter/min or more, and allow the generator to continue purging

for 24 to 48 hours before proceeding.

12) While remaining in the Purge mode, adjust setpoints to desired settings and allow the

saturation temperature to achieve its setpoint.

DEW PT oC -11.23
PPMv 2581.
PPMw 1605.
%RH 10.39
SATUR psi 70.29 24.35
SATUR oC 10.00 10.00
TEST psi 14.70
TEST
FLOW l/m 1.000 1.001

03/25/11 15:23:43 [294.6]

o

C 21.10

SETP

[10]

GEN

STOP

3-17

3.2.9 Stopping

SetPnt Actual

*FRST PT oC -10.00

CHNG

EDIT

PRG

GEN

The system may be stopped while either Generating or Purging. When stopped, all system
functions shutdown, pressure is vented, the printer is disabled (if attached), and the idle
Control/Display screen is shown. The system must be stopped in order to access the Edit and
Cal modes.

During this idle time when the system is either Stopped, in the Edit mode, or in the Cal mode, no
gas is flowing in the saturator. After extended periods of this idle time, the system must be
Purged again prior to further use.

To Stop the system and enter and idle mode:

1) From either the Generate or Purge modes, press [STOP]. Within a few seconds, all
system functions will shut down and the idle Control/Display screen will appear.

DEW PT oC -11.23
PPMv 2581.
PPMw 1605.
%RH 10.37
SATUR psi 70.29
SATUR oC 10.00
TEST psi
TEST
FLOW l/m 1.000

03/25/11 15:23:44 [294.6]

o

C

SETP

/CAL

The Stopped mode is easily distinguished from all others since all data in the
blank on this idle Control/Display screen.

Actual column is

3-18

3.2.10 Shutdown

A shutdown should be performed when servicing the 3900, or when use is not frequent enough
(such as day to day) to justify leaving the instrument in the Generate or Purge mode. When these
conditions apply, follow the complete shutdown procedure:

1) Press the [STOP] key. This disables the temperature control circuits, vents the system of

excess pressure, and closes all valves.

2) Allow all pressure to vent, then toggle main power switch to OFF.

3) Cap conditioned gas outlet.

4) Turn gas source OFF.

5) If maintenance is to be performed, disconnect power source from the system.

3.2.11 Changing Gas Supply

It is quite common to operate the system from a non-permanent gas source such as compressed
bottled gas or a LN

Dewar. These gas sources eventually become depleted and require

2

changing. To change the gas supply without completely stopping or shutting down the system:

1) Set the Flow setpoint to 0 liters/minute. Allow a few seconds for the flow and saturation

pressure indications to drop off. Temperature control will remain active.

2) Disconnect and remove the depleted gas source.

3) Connect to the new gas source.

4) Set the Flow setpoint back to the original setting. Within a few minutes, the system will

return to its previous state.

3.2.12 Printer (optional)

Reference Drawings 94M39901, 95M39914

An optional printer is used for hard copy output of system data and other parameters. While the
3900 humidity generator is operating in a Generate mode, data is output on a timed interval basis
when activated by the user. User alterable printer parameters are explained in section 3.3.2.6.
The printer is connected to the printer port using either a factory supplied or user made cable.
The required cable is simply a 9 to 25 pin AT Port Adapter (see drawings).

The [PRNT] key, when pressed, toggles to [PRNT ON] and causes measured system data to be
sent to the printer at regular time intervals (see section 3.3 to change default time and other print
parameters).

The [PRNT ON] key, when pressed, toggles to [PRNT], disables printer output, and sends a
form feed to the printer. This also occurs when switching to Purge mode or Stopping.

The <ENTER> or <•> key, when pressed, immediately sends one line of system data to the
printer regardless of the PRNT ON/OFF status, and independent of print time interval. Notice
that this print now feature is not active while in the Change Setpoint mode.

3-19

3.3 EDITING SYSTEM COEFFICIENTS AND PARAMETERS

CAL

EDIT

PRNT

DONE

ENTER AUTHORIZATION CODE

CAL

EDIT

PRNT

DONE

All of the calibration coefficients and system parameters may be viewed and/or edited by the
operator. The following is a summary of these items.

Category Editable Parameters
Temperature Coefficients Coefficients and Averaging
Pressure Coefficients Coefficients and Averaging
Flow Coefficients Coefficients and Averaging
Console Port Parameters Baud Rate, Parity, etc.
Printer Port Parameters Baud Rate, Parity, Print Interval, Lines per Page, etc.
Time & Date Time and Date of Real Time Clock
Misc User Parameters RH Calculation Method (WMO), Pressure Units, Date

Format, Molecular Weight of Carrier Gas

3.3.1 Edit Mode

The EDIT mode is used for the viewing and editing process.

1) From the idle Control/Display screen, press [EDIT/CAL]. Note, for this menu option to
appear the generator must not be in Generate or Purge mode. In a few seconds, the
following menu appears.

REPT

2) From this menu, press [EDIT].

3) At the prompt, enter in your authorization code (found at the back of the manual).

[ _ ]

REPT

3-20

An incorrect code prevents access and returns to step 3. A correct code results in the

SATURATION TEMP, Ts

EDIT

NEXT

PREV

DONE

MASS FOLW RATE

EDIT

NEXT

PREV

DONE

MASS FOLW RATE

-/

'E'

display of calibration coefficients.

Zero [-.877401 ]
Span [ 9.78206E-03]
Lin [-6.07702E-09]
Avg [ 10 ]

Last Cal Date 03/17/10

4) Using the [NEXT] and [PREV] keys, view any or all of the remaining coefficient and

parameter screens.

Zero [ 0 ]
Span [ 4E-04 ]
Lin [ 0 ]
Avg [ 10 ]

Last Cal Date 03/14/10

5) To edit a particular displayed value, press [EDIT]. The cursor begins flashing at the left

of the first parameter displayed.

Using [-/+], ['E'], arrow keys, and the numeric keys as necessary, change any or all

6) After Editing or Viewing, press [DONE]. Then from the next menu, press [DONE]

/+

Zero [ _0 ]
Span [ 4E-04 ]
Lin [ 0 ]
Avg [ 10 ]

Last Cal Date 03/14/10

displayed values as desired. Then press <ENTER>.

again. The system reinitializes back to the Control/Display screen.

3-21

3.3.2 Coefficients and Parameters

SATURATION TEMP, Ts

EDIT

NEXT

PREV

DONE

Each of the values on the various coefficient and parameter screens will be discussed in detail in
the following sections.

3.3.2.1 Temperature Coefficients

Zero [-.877401 ]
Span [ 9.98206E-03]
Lin [-6.07702E-09]
Avg [ 10 ]

Last Cal Date 03/17/10

The ZERO, SPAN, and LIN values are coefficients to the formula

Temp = A + Bx + Cx

2

where A = zero coefficient
B = span coefficient
C = linearity coefficient
x = output of the A/D converter card.

These coefficients are automatically computed during temperature calibration (section 4.2.2).

AVG is the amount of averaging applied to the displayed value. Averaging is applied with the
formula

New Value = {(Previous Value *AVG) + New Reading}/(AVG + 1)

An AVG of zero (0) effectively eliminates averaging. An AVG that is very large has a
correspondingly large averaging affect. Non-integer averaging amounts are allowable; however,
negative amounts should never be used. An AVG of approximately 10 is typical, while an AVG
of 1000 would be excessively high.

The date indicated at the bottom of the screen is the last date of calibration or the date of the
most recent editing of any of the listed values. The date shown may not be edited and is updated
automatically during calibration or when changing coefficients on this screen.

3-22

3.3.2.2 Reference Resistor Coefficients

LOW RANGE PRESSURE, Ps

EDIT

NEXT

PREV

DONE

These coefficients are factory set and similar to the temperature coefficients of section 3.3.2.1.

The reference resistor is approximately 10KΩ with coefficients chosen to provide a reference

value of approximately 0 °C. An AVG amount of approximately 50 is typical.

Any change made to either the reference resistor or the coefficients (with the exception of AVG)
requires that the temperature calibration of section 4.2.2 be performed on both temperature
probes.

3.3.2.3 Pressure Coefficients

The ZERO, SPAN, and LIN values are coefficients to the formula

These coefficients are automatically computed during pressure calibration (section 4.2.3)

AVG is the amount of averaging applied to the displayed value. Averaging is applied with the
formula

An AVG of zero (0) effectively eliminates averaging. An AVG that is very large has a
correspondingly large averaging affect. Non-integer averaging amounts are allowable; however,
negative amounts should never be used. An AVG of approximately 10 is typical, while an AVG
of 1000 would be excessively high.

The date indicated at the bottom of the screen is the last date of calibration or the date of the
most recent editing of any of the listed values. The date shown may not be edited and is updated
automatically during calibration or when changing coefficients on this screen.

Zero [-.0609974 ]
Span [ 1.96204E-03]
Lin [ 5.12663E-10]
Avg [ 10 ]

Last Cal Date 03/10/10

Pressure = A + Bx + Cx

2

where A = zero coefficient
B = span coefficient
C = linearity coefficient
x = output of the A/D converter card.

New Value = {(Previous Value *AVG) + New Reading}/(AVG + 1)

3-23

3.3.2.4 Flow Coefficients

MASS FLOW RATE

EDIT

NEXT

PREV

DONE

Zero [ 0 ]
Span [ 4E-04 ]
Lin [ 0 ]
Avg [ 10 ]

Last Cal Date 03/14/10

The ZERO, SPAN, and LIN values are coefficients to the formula

Flow = A + Bx + Cx

2

where A = zero coefficient
B = span coefficient
C = linearity coefficient
x = output of the A/D converter card.

These coefficients are automatically computed during flow calibration (section 4.2.4)

AVG is the amount of averaging applied to the displayed value. Averaging is applied with the
formula

New Value = {(Previous Value *AVG) + New Reading}/(AVG + 1)

An AVG of zero (0) effectively eliminates averaging. An AVG that is very large has a
correspondingly large averaging affect. Non-integer averaging amounts are allowable; however,
negative amounts should never be used. An AVG of approximately 10 is typical, while an AVG
of 1000 would be excessively high.

The date indicated at the bottom of the screen is the last date of calibration or the date of the
most recent editing of any of the listed values. The date shown may not be edited and is updated
automatically during calibration or when changing coefficients on this screen.

3-24

3.3.2.5 Console Port Parameters

CONSOLE PORT PARAMETERS

EDIT

NEXT

PREV

DONE

These parameters affect the manner in which the bi-directional RS-232C Console Port behaves.

Baud [ 2400 ]
Data [ 8 ]
Stop [ 1 ]
Parity [ 0 ]
EOL [ 13 ]
Cancel [ 3 ]

Baud: 300, 600, 1200, 2400, 4800, 9600, 19200 or 38400 bits per second

Data: 7 or 8 bit word size.

Stop: 1 or 2 stop bits

Parity: 0 for NO parity, 1 for ODD parity, or 2 for EVEN parity

EOL: The ASCII value of the desired End-Of-Line or terminator character for the 3900's

input buffer. Here, '13' is the ASCII value for a Carriage Return. Regardless of the
value of EOL, output from the console port of the 3900 is terminated with a carriage
return (ASCII 13) and linefeed (ASCII 10).

Cancel: The ASCII value of the desired cancel-the-line character. Sending this character clears

anything in the input buffer of the Console Port. Here, '3' is the ASCII value sent when
executing a Control-C on most computers.

Caution:

It is advised that these settings stay at factory defaults.

The reason for keeping factory defaults is because the higher baud rates may cause overflow and
task overrun issues with the processor board.

Factory Default Settings:

Baud: 2400
Data: 8
Stop: 1
Parity: 0
EOL: 13
Cancel: 3

3-25

3.3.2.6 Printer Port Parameters

PRINTER PORT PARAMETERS

EDIT

NEXT

PREV

DONE

DATE 10/11/12

EDIT

NEXT

PREV

DONE

These parameters affect the manner in which the unidirectional RS-232 Printer Port behaves. It
not only affects communication parameters, but time interval between printouts of system data,
and the number of lines to print per page.

Baud [ 9600 ]
Data [ 8 ]
Stop [ 1 ]
Parity [ 0 ]
Intrvl [ 60 ]
Lns/Pg [ 50 ]

Baud: 300, 600, 1200, 2400, 4800, 9600, 19200 or 38400 bits per second

Data: 7 or 8 bit word size.

Stop: 1 or 2 stop bits

Parity: 0 for NO parity, 1 for ODD parity, or 2 for EVEN parity

Intrvl: The print interval, or number of seconds between printouts of system data.

Lns/Pg: Lines per Page of printed data.

3.3.2.7 Time and Date

This screen is used to change the Time and/or Date of the Real Time Clock. Note that time is
input and displayed in 24-hour format. Also notice that the date is displayed in the date format
selected in Miscellaneous User Parameters (section 3.2.2.8).

TIME 15:29:39

Month [10 ]
Day [11 ]
Year [12 ]
Hour [15 ]
Min [29 ]
Sec [39 ]

3-26

3.3.2.8 Miscellaneous User Parameters

-

MISC USER PARAMETERS

EDIT

NEXT

PREV

DONE

This screen is used to change the Miscellaneous User Parameters.

WMO: When the Test Temperature is below 0 °C, %RH may be computed with respect to

P Units: 0 = psi Note that all pressure measurements are
1 = bar absolute with the exception of the input

T Units: 0 = °C (currently the only option)

F Units: 0 = liters/min (currently the only option)

Date Fmt: 0 = mm/dd/yy (U.S. format)
1 = dd/mm/yy (European format)

MW Gas: Molecular Weight of the carrier gas. Setting this value to zero (0) forces the system

Tt Type: Set this to zero (0) when using the standard 10K thermistor for Test Temperature

Pt Type: This must be set to the full scale range (in psiA) of the Test Pressure transducer.

Pg Warn: If the supply pressure drops below this pressure, the system emits a warning signal to

WMO [ 1 ]
P Units [ 0 ]
T Units [ 0 ]
F Units [ 0 ]
DateFmt [ 0 ]
MW [ 28.9645 ]
Tt Type [ 0 ]
Pt Type [ 50 ]
Pg Warn [ 50 ]
Pg Stop [ 35 ]
Ps Ctrl [ 1 ]

either water in accordance with the World Meteorological Organization (WMO=1) or
with respect to ice (WMO=0).

2 = hPa supply transducer which is gauge.

to revert back to the factory setting of 28.9645 (Molecular Weight of Air). When
using N

as the carrier gas, set the value to 28.0134. PPMw is the only parameter

2

directly affected by the value entered.

Note

The Molecular Weight does not alter the Enhancement Factors in
any way nor compensate for variations in solubility or
compressibility of various gasses. Therefore, when using a carrier
gas other than air or nitrogen, the validity of the Enhancement
Factors used in the calculation of humidity parameters cannot be
assured.

measurement. A setting of one (1) indicates that the optional low temperature 1K
thermistor is to be used. Any time that the test temperature probe is changed, it must
either be recalibrated, or its previously computed calibration coefficients must be re­entered.

indicate that the supply pressure is low.

3-27

Pg Stop: If the supply pressure drops below this pressure while generating or purging, the

-

system will shutdown.

Note

Ps Ctrl: The system has the capability of operating simply as a two-temperature generator

(Ps Ctrl = 0), or in a combined two-temperature two-pressure mode (Ps Ctrl = 1).
When operating as a two-temperature generator only, the expansion valve remains
fully open in order to minimize any pressure drop between the saturator and devices
under test. In this mode, all humidity changes require changes in the saturator
temperature. The lowest frost point obtainable in the two-temperature mode is
governed by the saturation temperature range as defined in section 1.3 Specifications.

If the Flow Rate setpoint is set to zero (0), the system does not
shutdown on low supply pressure. This allows gas supply bottles to
be changed while generating and purging without requiring that the
system be shutdown.

3-28

Section 4

CALIBRATION AND MAINTENANCE

4.1 GENERAL

The Model 3900 low humidity generation system requires little periodic maintenance.
Following the proper operating procedures as given in this manual will help assure trouble­free operation of this system.

4.2 CALIBRATION

Proper calibration of the temperature and pressure transducers is critical to the accuracy of
the generated humidity. Each time a transducer is calibrated its current calibration
coefficients and calibration date are stored to non-volatile memory.

Calibration of the system requires the following support equipment:

1) Temperature:

A. Temperature bath with a liquid medium (recommend Fluorinert FC-77, a 3M

product), a range of 0-50 °C, and stability of ±0.01 °C or better. Less stable baths
may require the use of a thermal block.

B. Standard or reference thermometer (PRT or Thermistor) for the range of -80 to 10 °C

for the saturator temperature, and 0 to 50 °C for the test temperature both having a
resolution of 0.01 °C or better. Thermometer accuracy should be ±0.03 °C or better.

2) Low Pressure Range:

A. Static gas pressure source for the pressure range of ambient to 50 psi, 3.5 bar, or 3500

hPa absolute with a stability of ±0.0025 psi, 0.00017 bar, 0.17 hPa or better.

B. Standard or reference pressure gauge for the range of ambient to 50 psi, 3.5 bar, or

3500 hPa absolute with a resolution of ±0.0025 psi, 0.00017 bar, 0.17 hPa or better.
Reference pressure accuracy should be ±0.025 psi, 0.0017 bar, 1.7 hPa or better.

3) High Pressure Range:

A. Static gas pressure source for the pressure range of ambient to 300 psi, 21 bar, or

21000 hPa absolute with a stability of ±0.01 psi, 0.00069 bar, 0.69 hPa or better.

B. Standard or reference pressure gauge for the range of ambient to 300 psi, 21 bar, or

21000 hPa absolute with a resolution of ±0.01 psi, 0.00069 bar, 0.69 hPa or better.
Reference pressure accuracy should be ±0.10 psi, 0.0069 bar, 6.9 hPa or better.

4) Flow:

A. Standard or reference flow meter for the range of 0 to 5 standard liters per minute

with a resolution of 0.01 L/min or better. Flow meter accuracy should be ±0.05 L/min
or better.

4-1

Calibration of all transducers is to be performed "in the system, as a system". There are no
provisions for, nor is it recommended that calibration of any of the transducers (temperature,
pressure, or flow) be performed while electrically disconnected from the generator. Since all
calibration is performed mathematically by the computer, there are no manual adjustments to
make.

Calibration is performed on all of the transducers by solving for the coefficients A, B, and C
of the quadratic formula:

Y=A+Bx+Cx

2

where x is the raw count (or uncalibrated output of the A/D

converter) while measuring a transducer, and

Y is the desired value (the standard or reference

transducer's reading) for the transducer being calibrated.

The three coefficients A, B, and C are found by applying three separate, distinct, and stable
references to each transducer, measuring the resulting raw count, then solving the
mathematical system of three equations with three unknowns. Since all of these calculations
are performed automatically by the 3900's embedded computer, the operator need only be
concerned with providing three known stable references required for the calibration of each
transducer.

4.2.1 A/D Card

Equipment Required: (None)

All calibration errors appearing in the A/D card will be accounted for automatically during
calibration of the temperature, pressure, and flow transducers. The card is also equipped with
built in auto-zero and auto-span circuitry which automatically and continually accounts for
short and long term drift in measurement accuracy. No user calibration is required. A card
suspected of extreme inaccuracies or malfunctions should be sent to the factory for repair.

4.2.2 Temperature Calibration

The systems EDIT/CAL mode may be used in conjunction with a precision temperature bath
for temperature probe calibrations. Only one temperature probe may be calibrated at a time.

By using the temperature bath to generate three known temperatures, all coefficients (ZERO,
SPAN, LINEARITY) can be calculated automatically by the embedded computer and used to
update the system calibration. A new expanded calibration report may also be printed at the
conclusion of the calibration sequence.

4-2

4.2.2.1 Test Temperature Calibration Procedure

CAL

EDIT

PRNT

DONE

TEMP

PRES

FLOW

DONE

Reference Drawing 95D39902

Equipment Required:

1. Temperature Bath (per section 4.2).

2. Standard or Reference thermometer (per section 4.2)

Calibration Procedure:

1) Bring a precision temperature bath with reference thermometer to the system, and
install the Test Temperature thermistor into temperature bath. If using water as the
fluid medium, do not submerse the probe completely or water may get into the probe
and damage the thermistor element.

2) From the main Control/Display screen, press the [EDIT/CAL] key. The Edit/Cal
menu appears.

3) Press the [CAL] key. The calibration menu appears.

REPT

CAL

CAL

CAL

4-3

4) Press the [TEMP CAL] key. The probe selection screen appears.

Satur Tmp

MARK

EXIT

OK

Satur Tmp 2464 24.89

LOW

MID

HIGH

EXIT

Satur Tmp 2464 24.89

-/

OOPS

/CLR

Count oC

*Test Tmp

QUIT

5) Using [MARK/CLR] and the down arrow key as necessary, mark the Test Tmp
probe. A marked probe is indicated with an asterisk on the left. Since the two
temperature probes require different calibration ranges, the computer will only allow
you to mark one probe at a time.

6) After marking the Test Tmp probe, press [OK] or <ENTER>. The LOW, MID, and
HIGH temperature reference values appear at the bottom of the screen, and within a
few seconds, actual data begins updating in the Count and &

o

C columns.

TEMP

Count oC

*Test Tmp 2516 25.28

Low Mid High

0 25 50

TEMP

TEMP

QUIT

7) Adjust the temperature bath to a LOW temperature point at or near 0 °C and allow
sufficient time for stability.

8) Once stable, press [LOW TEMP], and input the value of the Standard Thermometer
as the LOW temperature. Use [-/+] and arrow keys as necessary.

/+

Count oC

*Test Tmp 312 3.143

Low Mid High

3.16 _ 25 50

4-4

Then press <ENTER>. The LOW temperature value just entered, and the values of

TEST TEMPERATURE, Tt

PRNT

EXIT

SAVE

the marked probe are automatically saved to memory for later computation of
calibration coefficients.

Note - If a mistake was made during the temperature entry mode, use

[OOPS] rather than <ENTER>. This will cancel the
temperature entry mode and restore the previous "standard" and
"marked" probe values to memory. For instance, [OOPS] could
be used if the operator wanted to take the LOW temperature
point, but had mistakenly pressed the [MID TEMP] key.

9) Repeat step 8 for both a MID temperature (near 25 °C) and HIGH temperature (near

50 °C). Be sure to use the appropriate [MID TEMP] and [HIGH TEMP] keys.

Note - Using the [LOW TEMP], [MID TEMP], or [HIGH TEMP] key

more than once allows the previous point of the thermistor to be
over-written with the most current measured value. The
reference thermometer value will also be over-written with the
new value entered. The data stored is that which exists on the
screen in the "Count" column when the [LOW TEMP], [MID
TEMP], or [HIGH TEMP] key is pressed.

10) After all three temperature points have been taken, press [CALC COEF] to calculate
the new temperature coefficients for the probe which is marked. Unmarked probes
retain their previous coefficients. The current coefficients for the marked probe will
appear on the screen.

11) If a printer is attached, a calibration record of the temperature points and calculated

12) To update the calibration with new coefficients, press the [SAVE QUIT] key. To

COEF

Zero [ .0197137 ]
Span [ 9.98941E-03 ]
Lin [ 1.56924E-09 ]

QUIT

QUIT

coefficients is printed. Press the [PRNT COEF] key if additional printouts are
desired. This is the only opportunity to print this report. Upon leaving this screen,
the data used for report generation is lost (with the exception of the calculated
coefficients being displayed.)

abort without storing these new coefficients, press the [EXIT QUIT] key.

Note - If the new coefficients were printed but not SAVED, the new

coefficient values may be entered later using the EDIT mode
described in section 3.3.

4-5

13) Check the accuracy of the calibration if desired, by repeating steps 4 through 6,
however, don't "mark" any of the probes for calibration. Adjust the temperature bath
to any values between 0 and 50 °C and visually compare readings. When done, press
[EXIT QUIT].

14) At the calibration menu, press [DONE]. Then press [DONE] at the next menu. The
system reinitializes and the Control/Display screen appears.

15) To print a condensed coefficient report, listing temperature, pressure, and flow
coefficients together on one page, refer to section 4.2.5.

4-6

4.2.2.2 Saturation Temperature Calibration

CAL

EDIT

PRNT

DONE

Reference Drawings 95D39902

Equipment Required:

1. Standard or Reference Thermometer (per section 4.2)

2. 3/16" (4.5 mm) ball/hex driver

3. 9/16" (15 mm) wrench

4. 9/16" (15 mm) socket with 6" (15 cm) extension

Calibration Procedure:

The saturation temperature probe may be calibrated using the 3900's temperature controlled
saturator as the fluid bath.

1) For safety purposes, switch console power OFF and remove line cord.

2) Remove both side panels, and then remove the four socket head screws that secure the

counter top. Lift off the counter top and remove the 4" square foam insert that
insulates the saturator.

3) Using a 9/16" socket with 6" extension, loosen and remove the 1/4" Swagelok cap on

the Auxiliary Temperature Port.

4) Slide a 1/4" Swagelok nut and nylon ferrule set onto the shaft of the Standard

Thermometer and then insert it into the saturator's Auxiliary Temperature Port
approximately 3 to 4 inches. Seal the saturator by tightening the nut.

5) Install foam insulation around the saturator and the Standard Thermometer.

6) Replace side panels.

Note - The system must not be operated unless all panels are in place or the

refrigeration system will overheat.

7) Reinsert the line cord and switch console power ON.

8) From the main Control/Display screen, press the [EDIT/CAL] key. The Edit/Cal

menu appears.

REPT

4-7

9) Press the [CAL] key. The calibration menu appears.

TEMP

PRES

FLOW

DONE

*Satur Tmp

MARK

EXIT

OK

*Satur Tmp 2464 24.89

LOW

MID

HIGH

EXIT

SetPoint -40.0 Press

10) Press the [TEMP CAL] key. The probe selection screen appears.

Count oC

Test Tmp

CAL

CAL

CAL

/CLR

QUIT

11) Using [MARK/CLR] and the down arrow key as necessary, mark the Satur Tmp
probe. A marked probe is indicated with an asterisk on the left. To complete
selection, press [OK] or <ENTER>.

12) The saturation temperature calibration screen consists of two sections, the saturator
temperature control and the calibration data.

Control OFF ENTER

Count oC

Test Tmp 2135 21.35

Low Mid High

-70 -35 0

TEMP

TEMP

TEMP

QUIT

4-8

To obtain access to the setpoint control, press the <ENTER> key on the numeric

*Satur Tmp 2464 24.89

-/

ON/

SetPoint -4_0.0

*Satur Tmp 10 0.102

-/

OOPS

SetPoint 0.00 Press

keypad.

Control OFF

Count oC

Test Tmp 2135 21.35

Low Mid High

-70 -35 0

/+

*OFF

At this time, the cursor will begin flashing on the control setpoint in the saturator

temperature control section. The temperature setpoint may be changed to any value
within the operational limits of the saturator by using the numeric keypad, the arrow
keys and the [-/+] key as necessary. To enable the saturator temperature control at the
setpoint entered, press the [ON/OFF] toggle key. To return to the calibration section,
press <ENTER> on the numeric keypad.

Using the method described above, enter the high temperature setpoint and enable the

control. Allow sufficient time for movement to and stability at the setpoint.

13) Once stable, press [HIGH TEMP], and input the value of the Standard Thermometer
as the HIGH temperature. Use [-/+] and arrow keys as necessary.

Then press <ENTER>. The HIGH temperature value just entered, and the values of

the marked probe are automatically saved to memory for later computation of
calibration coefficients.

Note - If a mistake was made during the temperature entry mode, use

14) Repeat steps 12 and 13 for both a MID temperature and LOW temperature. Be sure
to use the appropriate [MID TEMP] and [LOW TEMP] keys.

Control ON ENTER

Count oC

Test Tmp 2135 21.35

Low Mid High

-70 -35 0.307 _

/+

[OOPS] rather than <ENTER>. This will cancel the
temperature entry mode and restore the previous "standard" and
"marked" probe values to memory. For instance, [OOPS] could
be used if the operator wanted to take the HIGH temperature
point, but had mistakenly pressed the [MID TEMP] key.

4-9

Note - Using the [LOW TEMP], [MID TEMP], or [HIGH TEMP] key

SATURATION TEMP, Ts

PRNT

EXIT

SAVE

more than once allows the previous point of the thermistor to be
over-written with the most current measured value. The
reference thermometer value will also be over-written with the
new value entered. The data stored is that which exists on the
screen in the Count column when the [LOW TEMP], [MID
TEMP], or [HIGH TEMP] key is pressed.

15) After all three temperature points have been taken, press [CALC COEF] to calculate
the new coefficients for the probe which is marked. Unmarked probes retain their
previous coefficients. The current coefficients for the probe will appear on the screen.

COEF

Zero [-.877401 ]
Span [ 9.98791E-03]
Lin [-6.84686E-09]

QUIT

QUIT

16) If a printer is attached, a calibration record of the temperature points and calculated
coefficients is printed. Press the [PRNT COEF] key if additional printouts are
desired. This is the only opportunity to print this report. Upon leaving this screen,
the data used for report generation is lost (with the exception of the calculated
coefficients being displayed.)

17) To update the calibration with the new coefficients, press the [SAVE QUIT] key. To
abort without storing these new coefficients, press the [EXIT QUIT] key.

Note - If the new coefficients were printed but not SAVED, the new

coefficient values may be entered later using the EDIT mode
described in section 3.3.

18) Check the accuracy of the calibration if desired, by repeating steps 10 through 12,
however, don't "mark" any of the probes for calibration. Adjust the Saturator control
setpoint to any values between -80 and +12 °C and visually compare readings. When
done, press [EXIT QUIT]

19) At the calibration menu, press [DONE], then press [DONE] at the next menu. The
system reinitializes and the Control/Display screen appears.

20) To print a condensed coefficient report, listing temperature, pressure, and flow
coefficients together on one page, refer to section 4.2.5.

21) For safety purposes, switch the console power off and remove line cord.

22) Remove Standard Temperature probe and reinstall Swagelok cap. Reinstall the foam
insulation, counter top and replace side panels. The system must not be operated
unless all panels are in place.

4-10

4.2.3 Pressure Transducer Calibration

Pressure Transducer Calibration is typically performed in a calibration laboratory and
requires that the transducers be removed from the pneumatic system of the 3900, but must
remain electrically connected. The pressure readings must be precise in order to retain
accurate relative humidity calculations. Since the 3900 may be operated and calibrated in
various pressure units (psi, bar, hPa), ensure that the system is set to the desired units (section

3.3) prior to performing the pressure calibration.

Reference Drawing 95D39902

Equipment Required:

1. Static pressure source, and standard or reference measurement, with absolute pressure

range of ambient to 50 psi, 3.5 bar, or 3500 hPa (per section 4.2).

2. Static pressure source, and standard or reference measurement, with absolute pressure

range of ambient to 300 psi, 21 bar, or 21000 hPa (per section 4.2).

3. 9/16" (15 mm) and 11/16" (18 mm) open end wrenches.

4. Flat blade screwdriver.

Pressure Conversion Factors:

psi = bar * 14.503774
psi = hPa * 0.014503774

bar = psi * 0.068947573

bar = hPa * .001

hPa = psi * 68.947573

hPa = bar * 1000

4-11

4.2.3.1 Saturator and Test Pressure Calibration Procedure

Reference Drawing 95D39902

1) For safety purposes, switch console power OFF and remove the line cord.

2) For safety purposes, turn OFF or disconnect air supply.

CAUTION!

ALL SYSTEM PRESSURE MUST BE
VENTED BEFORE PROCEEDING.

3) Bring the pressure source to the generator or take the generator to the pressure
calibration lab.

4) To access the saturator pressure transducers, remove left console panel.

5) Slowly disconnect pressure transducers (11/16" & 9/16" wrench required). Some
static pressure may still exist in the saturator and pressure transducers. This pressure
should be allowed to vent slowly through the fitting during removal. Using a
screwdriver, pry open the round snap-lock transducer mounts, and remove the
transducers. Ensure the electrical connectors are in place.

6) Reinsert line cord and switch console power ON. Wait a few moments for the softkey
menu to appear. Allow approximately 30 minutes or more for warm-up of the
pressure transducer electronics.

7) Connect the pressure source to the transducer to be calibrated (only one transducer at
a time may be calibrated).

Note - Each transducer is operated over a limited range and requires

calibration within this range only.

A) Low Range Saturation Pressure Transducer - Calibrate from ambient

to approximately 50 psi, 3.5 bar, or 3500 hPa absolute.

B) High Range Saturation Pressure Transducer - Calibrate from

ambient to approximately 300 psi, 21 bar, or 21000 hPa absolute.

C) External Test Pressure Transducer - Calibrate from its lowest to

highest range of actual use (typically ambient to full scale).

4-12

8) Press the [EDIT/CAL] key, then the [CAL] key. The calibration menu appears.

TEMP

PRES

FLOW

DONE

*_Low Range

MARK

EXIT

OK

*Low Range 6508 12.18

-/

OOPS

CAL

CAL

CAL

9) Press the [PRES CAL] key.

10) Using [MARK /CLR] and the down arrow key as necessary, mark the transducer to be
calibrated. A marked transducer is indicated with an asterisk in the left most display
column. Since each of the transducers require a different calibration range, the
computer will only allow you to mark one transducer at a time.

/CLR

Count Psi

Hi Range
Ext Test
Supply

QUIT

11) Confirm selection by pressing [OK] or <ENTER>.

12) Apply the lower recommended calibration pressure and watch the displayed value of
the marked transducer. Once stable, press the [LOW PRES] key and enter the
reference pressure.

/+

Count psi A

Hi Range 1513 12.19
Ext Test 7385 12.19
Supply 17506 250.9

Low Mid High

12.212_ 30 50

4-13

Note - For all transducers, ambient pressure may be used for the low

*Low Range 15538 30.11

-/

OOPS

*Low Range 15538 30.11

-/

OOPS

LOW RANGE PRESSURE, Ps

PRNT

EXIT

SAVE

pressure calibration point.

Note - If a mistake is made during reference pressure entry, pressing

the [OOPS] key cancels the data entry mode, leaving all values
for that point unchanged.

13) Apply the mid range pressure and watch the displayed value. Once stable, press the
[MID PRES] key and enter the reference pressure.

/+

Count psi A

Hi Range 1513 12.19
Ext Test 7385 12.19
Supply 29806 250.9

Low Mid High

12.212 29.989_ 50

14) Apply the upper recommended pressure and watch the displayed value. Once stable,
press the [HIGH PRES] key and enter the reference pressure.

/+

Count psi A

Hi Range 1513 12.19
Ext Test 7385 12.19
Supply 29806 250.9

Low Mid High

12.212 29.989_ 50

15) Press the [CALC COEF] key. All coefficients for the marked transducer will be
calculated, and appear on the LCD display.

COEF

Zero [-.609974 ]
Span [ 1.96204E-03]
Lin [ 5.12663E-09]

QUIT

QUIT

4-14

16) If a printer is attached, a calibration record of the pressure points and calculated
coefficients is printed. Press the [PRNT COEF] key if additional printouts are
desired. This is the only opportunity to print this report. Upon leaving this screen,
the data used for report generation is lost (with the exception of the calculated
coefficients being displayed.)

17) To save the coefficients, press [SAVE QUIT]. The coefficients will be stored to non­volatile memory. To abort the calibration without saving the coefficients just
calculated, press [EXIT QUIT]. The previous coefficients will be reinstated.

18) Check the accuracy of the calibration if desired by repeating steps 9 through 11
however don't "mark" any of the probes. Apply various pressures within the range of
the transducer and visually compare the readings.

19) Repeat steps 7 through 18 for the high-pressure saturator and the external test pressure
transducers, using the suggested LOW, MID, and HIGH pressures indicated on the
screen.

20) For safety purposes, switch main console power to OFF and disconnect line cord.

21) Re-install the pressure transducers (0-50 psiA Saturator transducer, TR3, goes on the
right next to the solenoid valve.) Tighten all connections 1/4 turn past finger tight.

22) Replace left console panel. The system must not be operated unless all panels are in
place.

23) To print a condensed coefficient report, listing temperature, pressure, and flow
coefficients together on one page, refer to section 4.2.5.

4-15

4.2.3.2 Supply Pressure Transducer Calibration

TEMP

PRES

FLOW

DONE

Low Range

MARK

EXIT

OK

The supply pressure measurement, while indicated on the screen, is not critical to the
accuracy of the 3900 and is not used in the humidity calculations.

Reference Drawing 95D39902

Equipment Required:

1. Gas Supply of at least 300 psi, 21 bar, or 21000 hPa gauge.

Calibration Procedure:

1) For safety purposes, switch the console power OFF and then remove front console
panel.

2) Switch console power ON. Wait a few minutes for the softkey menu to appear.
Allow approximately 30 minutes or more for warm-up of the pressure transducer
electronics.

3) Press the [EDIT/CAL] key, then the [CAL] key. The calibration menu appears.

CAL

CAL

CAL

4) Press the [PRES CAL] key.

5) Using [MARK /CLR] and the down arrow key as necessary, mark the Supply
pressure transducer.

/CLR

Count Psi

Hi Range
Ext Test
*_Supply

QUIT

6) Confirm the selection by pressing [OK] or <ENTER>.

4-16

7) Apply the lower recommended calibration pressure by adjusting the internal pressure

Low Range 6508 12.18

-/

OOPS

regulator REG fully counter clockwise and watch the displayed value. Once stable,
press the [LOW PRES] key and enter the reference pressure as read from the
regulator's pressure gauge (zero in this case). Since the regulator is a non-relieving
type, pressure is vented through the pump purge solenoid. This is a very low flow and
may take several minutes to vent the pressure to zero.

/+

Count psi G

Hi Range 1513 12.19
Ext Test 7385 12.19
*Supply 5236 0.729

Low Mid High

0_ 150 300

Note - If a mistake is made during reference pressure entry, pressing

the [OOPS] key cancels the data entry mode, leaving all values
unchanged.

8) Apply the mid range and high range pressure by adjusting the internal pressure

regulator and watch the displayed value. Once stable, press the [MID PRES] or
[HIGH PRES] key as applicable and enter the reference pressure as read from the
regulator's pressure gauge.

9) Press the [CALC COEF] key. All coefficients for the marked transducer will be

calculated, and appear on the LCD display.

10) If a printer is attached, a calibration record of the pressure points and calculated
coefficients is printed. Press the [PRNT COEF] key if additional printouts are
desired. This is the only opportunity to print this report. Upon leaving this screen,
the data used for report generation is lost (with the exception of the calculated
coefficients being displayed.)

11) To save the coefficients, press [SAVE QUIT]. The coefficients will be stored to non­volatile memory. To abort the calibration without saving the coefficients just
calculated, press [EXIT QUIT]. The previous coefficients will be reinstated.

12) At the calibration menu, press [DONE]. Then press [DONE] at the next menu. The
system reinitializes and the Control/Display screen appears.

13) Replace front console panel. The system must not be operated unless all panels are in
place.

14) To print a condensed coefficient report, listing temperature, pressure, and flow
coefficients together on one page, refer to section 4.2.5.

4-17

4.2.4 Flow Meter Calibration

CAL

EDIT

PRNT

DONE

The flow measurement, while indicated on the screen, is not critical to the accuracy of the
generated humidity and is not used in the humidity calculations. Flow calibration accuracy
depends upon the requirements of the user.

Equipment Required:

1. Standard or Reference flow meter (per section 4.2).

4.2.4.1 Flow Calibration Procedure

Reference Drawing 95D39902

The calibration for the flow meter is slightly different than for the temperatures and
pressures, and does not require the removal of the flow meter from the system.

1) Using appropriate fittings, connect a flow meter reference instrument to the gas outlet
port of the system.

2) Generate a flow rate of approximately 1.0 L/min. Once stable, note the readings of
the reference flow meter and of the indicated flow of the 3900.

3) Change the flow to 2.0 L/min. Once stable note both readings again.

4) Press [STOP]. Once the shutdown is complete, press [EDIT/CAL]. The following
menu appears.

REPT

4-18

5) Press [CAL]. The calibration menu appears.

TEMP

PRES

FLOW

DONE

*Mass Flow 4 .0144

LOW

MID

HIGH

EXIT

_Mass Flow

MARK

EXIT

OK

CAL

CAL

CAL

6) Press [FLOW CAL].

7) Press [MARK/CLR] to mark the flow meter (indicated by an asterisk to its left).

/CLR

Count l/min

QUIT

8) Press [OK]. Within a few seconds, the measured flow readings begin updating.

FLOW

Count l/min

Low Mid High

0 1.0 2.0

FLOW

FLOW

QUIT

4-19

9) Allow a few moments for stability of the flow indication. This "no flow" condition

*Mass Flow 4 .0144

-/

OOPS

*Mass Flow 2500 1.000

-/

OOPS

*Mass Flow 5000 2.000

-/

OOPS

will be used for a LOW flow reference. Press [LOW FLOW] to store this point.
Then press <ENTER>.

/+

Count l/min

Low Mid High

0_ 1.0 2.0

10) Using the 1.0 liter data obtained in step 2, calculate the following:

1.0 + (Reference Indication) - (3900 Indication)

Press [MID FLOW] and enter this calculated value.

/+

Count l/min

Low Mid High

0 0.98 _ 2.0

11) Using the 2.0 liter data obtained in step 3, calculate the following:

2.0 + (Reference Indication) - (3900 Indication)

Press [HIGH FLOW] and enter this calculated value.

/+

Count l/min

Low Mid High

0 0.98 1.97 _

4-20

12) Press [CALC COEF] to calculate the new flow meter coefficients. These new

MASS FLOW RATE

PRNT

EXIT

SAVE

coefficients appear on the display.

COEF

Zero [-1.56852E-03]
Span [ 3.92120E-04]
Lin [ 2.62802E-09]

QUIT

QUIT

13) If a printer is attached, a calibration record of the flow points and calculated
coefficients is printed. Press the [PRNT COEF] key if additional printouts are
desired. This is the only opportunity to print this report. Upon leaving this screen,
the data used for report generation is lost (with the exception of the calculated
coefficients being displayed.)

14) To save the coefficients to non-volatile memory, press [SAVE QUIT]. To discard
these new coefficients and revert to the previous ones, press [EXIT QUIT].

15) At the calibration menu, press [DONE]. At the next menu, press [DONE] again. The
system reinitializes to the Control / Display screen.

16) To print a calibration report, refer to section 4.2.5.

4-21

4.2.5 Printing Condensed Coefficient Report

If a printer is connected to the Printer Port, a Coefficient Report for the temperature, pressure
and flow transducers may be printed. This condensed report lists the current system
calibration coefficients and calibration date for all of the system transducers. This report is
printed from the Edit/Cal menu.

To print the report:

1) From the idle Control/Display screen press [EDIT/CAL], or from the Cal menu press
[DONE]. Both actions should bring up the Edit/Cal menu.

2) Ensure the printer is on, then press [PRNT REPT]. The Coefficient Report will be
sent to the printer. See sample below.

3) Press [DONE] to return to the Control/Display screen.

Coefficient Report

for

TSC Model 3900 Low Humidity Generator

S/N: XXXXXXX

Date: MM/DD/YY

Temperature Zero Span Linearity Cal Date

Saturation Temperature 0.00000E+00 1.00000E-02 0.00000E+00 MM/DD/YY

Test Temperature 0.00000E+00 1.00000E-02 0.00000E+00 MM/DD/YY

Temp Reference Resistor -2.50000E+01 1.00000E-02 0.00000E+00 MM/DD/YY

_____ _____ _____ _____ _____

Pressure Zero Span Linearity Cal Date

Low Range Sat 0.00000E+00 2.00000E-03 0.00000E+00 MM/DD/YY

Hi Range Sat 0.00000E+00 1.20000E-02 0.00000E+00 MM/DD/YY

External Test 0.00000E+00 2.00000E-03 0.00000E+00 MM/DD/YY

Supply 0.00000E+00 2.00000E-02 0.00000E+00 MM/DD/YY

_____ _____ _____ _____ _____

Flow Zero Span Linearity Cal Date

Mass Flow Rate 0.00000E+00 4.00000E-04 0.00000E+00 MM/DD/YY

Certified by ________________________

Date ________________________

4-22

4.3 ROUTINE MAINTENANCE

4.3.1 Console Intake: Monthly

Reference Drawing 94D39901

Equipment Required: (None)

Cleaning Procedure:

1) Locate console intake on left side of console.

2) Remove any obstruction and dust from console panel.

3) Remove left console panel and dust finned aluminum condenser.

4) Replace left console panel

4.3.2 7 Micron Gas Input Filter: Yearly

Reference Drawing (pneumatic)

Equipment Required:

1. 9/16" open end wrench

2. Two 3/4" open-end wrenches.

Filter Change Out Procedure:

1) For safety purposes, switch console power OFF and remove line cord.

2) Disconnect facility gas supply.

3) Remove right side console panel.

4) Using both a 9/16" and a 3/4" wrench, remove inline filter from gas supply line

tubing.

5) Using both 3/4" wrenches, disassemble filter body and remove filter from tapered

bore.

6) Insert new filter element into tapered bore.

7) Reassemble filter body and tighten securely.

8) Replace inline filter into gas supply line tubing.

9) Replace console access panel and reconnect console power.

4-23

4.4 SERVICING REFRIGERATION AND FLUID SYSTEMS

Reference Drawing 95S39917

Before starting repairs on either refrigeration system, the serviceman should be familiar with
the location of all components of the stages. Especially important is the identification of the
high and low stages of the refrigeration system. The high stage compressor always connects
directly to the air-cooled condenser. The low stage compressor connects directly to the oil
separator. By following the tubing and referring to the flow diagram, most parts can easily be
traced. By necessity, some parts are foam insulated and rarely require servicing.

4.4.1 Fault Isolation and Diagnosis

In the event of system failure, before attaching gauges or opening either refrigeration circuit,
every effort should be made to ensure that the problem is not electrical in nature. If
compressors are suspected, check the compressor relays, overloads, and capacitors. Check
the temperature control contacts and associated wiring. Use the above procedure on the high
stage first, as it is impossible to run the low stage system unless the high stage is functional
and has had time (10 minutes) to cool the interstage heat exchanger.

Although great care is taken in the design and manufacture, these systems can be subject to
normal failures. Refrigerant leaks, moisture, and component failure can be diagnosed in
much the same way as in other refrigeration equipment. There are some differences,
especially with respect to the low stage.

4.4.1.1 Moisture In Low Stage

This can be diagnosed and repaired as in any medium temperature refrigeration system.

Excess moisture in the low stage results in ice blocking the capillary tube; however, the
replacement of the drier is not possible as it is located within the foam insulation. The
cabinet must be allowed to warm up to room temperature so that sufficient heat will enter the
interstage heat exchanger. Then proceed in this order:

1) Bleed off all refrigerant from the low stage.

2) Evacuate for 8 to 12 hours.

3) Replace vacuum with ultra dry nitrogen to a pressure of 150 psiG.

4) Bleed off pressure.

5) Repeat steps 2-4 three times.

6) Evacuate again as in step 2.

7) Replace refrigerant with specified amount (Section 4.4.2).

4-24

4.4.1.2 Oil In Low Stage Evaporator

The migration of compressor oil to the low stage capillary tube will create symptoms similar
to those of moisture. Solidification does occur as the oil reaches the capillary tube. This can
reduce flow resulting in lower suction pressure. If the cabinet is warmed to a temperature of ­18 °C or higher and then restarted, the oil will be flushed out of the capillary tube and will
not build up again for a week or more. Moisture will show up much sooner, usually in a
matter of hours.

4.4.2 Refrigerant Charge

Saturator Refrigeration: High stage requires fourteen (13) ounces of R-134A. Low stage
requires six (9.5) ounces of R-23.

4.4.3 Saturator Fluid System

The saturator fluid system uses methyl alcohol (methanol) as a heat transfer medium because
of its low freezing point. This fluid is circulated by a magnetically coupled centrifugal pump
(FP1) at approximately two gallons per minute. This pump has an approximate life of 10,000
hours and may ultimately need service. Should this system require repair, extreme caution is
required in the draining and filling due to the flammability of methanol.

CAUTION!

THIS SYSTEM CONTAINS METHYL ALCOHOL (METHANOL)

FLAMMABLE AND POISONOUS

Keep away from sparks, flames, or other ignition sources. Avoid
prolonged or repeated breathing of vapors or contact with skin. Do
not allow material to contaminate water sources.

4.4.4 Methanol System Drain / Fill Procedure

Reference Drawings 95D39902 & 08D39922

Equipment Required:

1. 3/16" & 3/8" ball/hex driver

2. 7/8" socket with 6" extension

3. 4 feet of 1/4" OD tube with 1/4" Swagelok nut and ferrules attached on one end

4. 5.675 liters (1.5 gallons) of anhydrous methanol

5. Marked 7.5 liter (2 gallon) container for used methanol

6. Funnel

7. Gloves and goggles

4-25

To drain saturator fluid system, proceed as follows:

1) Disconnect power source from console.

2) Remove right side console panel.

3) Locate saturator drain valve (located below pump on right side of console). Remove
insulation on drain valve outlet. Remove Drain Valve Cap and connect 1/4" hose to
drain valve. Place other end of drain hose into two gallon container.

4) Open drain valve and drain methanol.

5) After draining methanol, close drain valve, remove drain hose and replace Drain
Valve Cap and insulation.

6) Repairs or shipment may be made at this time.

To fill saturator fluid system, proceed as follows:

1) Disconnect power source from console.

2) Locate and remove the four counter top bolts using 3/16" ball/hex driver, then remove
the counter top.

3) Remove circular insulation and using the 3/8" ball/hex driver remove the Methanol
Expansion Tank Fill Port Plug.

4) Locate RTD1 Access Insulation and remove. Using the 7/8" socket with 6"
extension, remove the Saturator Methanol Port Cap from the top of the saturator.

5) Insert the funnel into the Methanol Expansion Tank Fill Port. Slowly and carefully
fill the saturator assembly until methanol is observed just below the Saturator
Methanol Port Fitting located on top of the saturator (in the square insulation area).

Note - The methanol must be added slowly as it is being gravity

fed through 3/8" tubing between the methanol expansion
tank and the saturator. Do not allow funnel to fill.

Methanol degrades the urethane foam insulation; sponge
dry any methanol spilled during the filling operation!

6) Replace the Saturator Methanol Fill Port Cap (tighten 1/4 turn past finger tight).

7) Replace Methanol Expansion Tank Fill Port Plug.

8) Replace all insulation.

9) Replace counter top.

4-26

4.5 ERROR CODES and TROUBLESHOOTING

Prior to system start-up, and during humidity generation, the system monitors itself for errors
and sources of possible malfunction. When a catastrophic error occurs, the system
automatically shuts down, then alerts the operator with a visual flashing message and an
audible tone. The visual message displays the error number and a brief description of the
problem.

It is possible (in many cases probable) to have multiple errors occurring at one time. Under
these circumstances, the error codes simply add together algebraically, and all of the
associated messages are displayed in turn. Any error code greater than 16383 will be
displayed as a negative number. In this case, simply add 65536 to the displayed number to
calculate the appropriate code. While it is not necessary to understand the error code system,
it is important to write down the error code number exactly as it appears on the screen when
consulting the factory for technical support. Little can be done to ascertain the nature of the
problem without the exact error code.

The following is a list of error codes and a brief description of each.

ERROR CODE DESCRIPTION

1 Expansion Valve Not Closing
2 Flow Valve Not Closing
4 Low Supply Pressure
8 Cabinet Temperature Overrange
32 Reference Temperature Underrange
48 Reference Temperature Overrange
64 Test Temperature Underrange
80 Test Temperature Overrange
128 Saturator Temperature Underrange
144 Saturator Temperature Overrange
512 Test Pressure Underrange
768 Test Pressure Overrange
1024 Low Range Saturator Pressure Underrange
1280 Low Range Saturator Pressure Overrange
2048 High Range Saturator Pressure Underrange
2304 High Range Saturator Pressure Overrange

Error 1 - Expansion Valve Not Closing

This indicates that while attempting to close the expansion valve, the HOME position
limit switch closure was not detected. This could mean that either the valve is not
moving properly or the switch is mechanically or electrically malfunctioning.

Error 2 - Flow Valve Not Closing

This indicates that while attempting to close the flow valve, the HOME position limit
switch closure was not detected. This could mean that either the valve is not moving
properly or the switch is mechanically or electrically malfunctioning.

4-27

Error 4 - Low Supply Pressure

This indicates that there is insufficient gas supply pressure to continue or that icing has
occurred (section 3.2.5.1 Note 2). Check the gas supply. A malfunction of solenoid
valve SOL1 or solid state relay SSR5 may also cause this problem.

Error 8 - Cabinet Temperature Overrange

The measured cabinet temperature is too high. Most likely causes include a blocked or
clogged intake vent on the left side of the unit, a blocked outlet at the back of the unit, or
a faulty fan. Anytime the rear panel is removed and reinstalled, ensure that the fan gets
plugged in.

Error 32 - Reference Temperature Underrange

The temperature reference resistor is well below its nominal value of 0 °C. This typically
indicates a faulty reference resistor or a malfunctioning A/D converter card.

Error 48 - Reference Temperature Overrange

The temperature reference resistor is well above its nominal value of 0 °C. This typically
indicates a faulty reference resistor or a malfunctioning A/D converter card.

Error 64 - Test Temperature Underrange

The indicated test temperature is below -80 °C. One possible cause could be the testing
environment temperature is less than -80 °C. The most likely cause is a malfunction of
the temperature probe.

Error 80 - Test Temperature Overrange

The indicated test temperature is above 100 °C. One possible cause could be the testing
environment temperature is greater than 100 °C. The most likely cause is a malfunction
of the temperature probe.

Error 128 - Saturation Temperature Underrange

The indicated saturation temperature is below -85 °C. The most likely cause is a
malfunction of the temperature probe. This could also be caused by a faulty heat control
circuit or a short in SSR0.

Error 144 - Saturation Temperature Overrange

The indicated saturation temperature is above 30 °C. The most likely cause is a
malfunction of the temperature probe.

Error 512 - Test Pressure Underrange

The test pressure transducer indicates a pressure that is less than 10 psiA. The most likely
cause is a pressure transducer malfunction or calibration error.

4-28

Error 768 - Test Pressure Overrange

The test pressure transducer indicates a pressure more than 10% above its full scale
reading. The most likely cause is a pressure transducer malfunction or calibration error.

Error 1024 - Low Range Saturation Pressure Underrange

The low range saturation pressure transducer indicates a pressure less than 10 psiA. The
most likely cause is a pressure transducer malfunction or calibration error.

Error 1280 - Low Range Saturation Pressure Overrange

The low range saturation pressure transducer indicates a pressure more than 10% above
its full scale reading. One possible cause would be a malfunction or leak in the pressure
select solenoid, SOL4. This error could also be caused by a pressure transducer
malfunction or calibration error.

Error 2048 - High Range Saturation Pressure Underrange

The high range saturation pressure transducer indicates a pressure less than 10 psiA. The
most likely cause is a pressure transducer malfunction or calibration error.

Error 2304 - High Range Saturation Pressure Overrange

The high range saturation pressure transducer indicates a pressure more than 10% above
its full scale range. The most likely cause is a pressure transducer malfunction or
calibration error.

4-29

Section 5

3900 PARTS LISTS

Find # Qty. Description Part Number

A/D 1 Analog A/D Card MCM7418
ATB 1 Analog Terminal Board ADP7409TB
C1 1 Compressor, R-134A COMPR-220V/50HZ
C2 1 Compressor, R-23 COMPR-220V/50HZ
CBS1 1 Power Switch PWRSW-2P
CF1 1 Fan, Console MR77B3
CF2 1 Fan, Console FN624N
CON1 1 Condenser, R-134A BT-COND
CON2 1 Condenser, R-13 D95A00186
CP1,2 2 Capacitor, 10µF 35V Elec *********
CPU 1 CPU Card D96A39021
CV1 1 Valve, Check S4C-1/3
EX1 1 Exchanger, Heat D95A00185
FB1 1 Core, Ferrite FERSPLTCORE
FD1,2 2 Filter/Drier C-032-S
FP1 1 Pump, Centrifugal D95A00192
G1 1 Gauge, Pressure J2258
H1 1 Heater, Cartridge N9N-1560
H2 4 Heater, Foil HK5161
H3 6 Heater, Foil ** HK5579
HLS1 1 Heat Limit Switch A19AAF-12
KB 1 Keypad D94M39205
LCD-CON 1 Display Controller D96A00228_39

LCD 1 Liquid Crystal Display DMF6104
LCD-INV 1 Inverter Board (Back-Lite) CXAM10L
LF1 1 Filter, Inline S4F-7
MEM 1 Memory Card D96A39022
MOV1 3 Varistor, Metal Oxide MOV1
OS1 1 Separator, Oil D40B0010
PLF1 1 Filter, Power Line F1700BB03
PS1 1 Supply, ±15/5VDC Power HTAA-16W-A
PS2 1 Supply, +24VDC Power MAP55-1024
RECR 1 Receiver, Refrigeration BT-RECR
REG 1 Regulator, Pressure CONREG
RTD1 1 Sensor, Temperature THRMPB3
RTD2 1 Sensor, Temperature BTPROBE3
RV1 1 Valve, Relief S4C-150
SAT 1 Saturator D95A00026
SL1,2 2 Switch, Limit MCRSW2
SM-1,2 2 Motor, Stepper PX243G
SMD-1,2 2 Driver, Stepper Motor RD-023MS
SOL1-4 4 Valve, Solenoid A2012
SOL5 1 Valve, Solenoid V8264G9-24V
SPKR 1 Minilert Audible Signal MINLRT

5-1

3900 PARTS LIST (continued)

Find # Qty. Description Part Number

SSR0-5 6 DC SSR Module G4DC5
SSR6,7 2 AC SSR Module G4AC5
SSR8-10 3 10 Amp SSR R24D10
SSRB 1 SSR Module Board OP2512
TR1 1 Transducer, Pressure ST2500G1
TR2 1 Transducer, Flow BK5860E
TR3 1 Transducer, Pressure PTE50
TR4 1 Transducer, Pressure DCT300A
TR5 1 Transducer, Pressure PTE50
* DCT150A
TB1 20 Terminal Block ABWM3
TIB 1 Terminal Interface Board TBD-100
TM1 1 Tank, Methanol Expansion D95A00187
V1 1 Valve, Flow D95A00172
V2 1 Valve, Expansion D95A00172
V3 1 Valve, Refrigeration Expansion NIF-1/2-C
V5 1 Valve, Metering SS-2MA

* High Pressure (HP) Option Parts
** High Air Flow (39-HAF) Option Parts

5-2

30.0

DWN

REV

.

FDWF DRAWN TO SW 8/12/2013 MJG

GDWF UPDATED SHEET FO

CONDITIONED GAS OUTLET

FILL PORT - PURE WATWE ONLY

DESCRIPTION DATE APP. B

REVISIONS

RMAT

Y

8/13/2018 BB

LEFT SIDE

AIR INTAKE

COMPUTER
& PRINTER
INTERFACE

33.0

~37.5

DO NOT SCALE
FROM DRAWING

3900

USED ONNEXT ASSY

APPLICATION

TOP

FRONT

THUNDER SCIENTIFIC CORPORATION

THIRD ANGLE
PROJECTION

TOLERANCES

UNLESS NOTED OTHERWISE

7 8 9

TEST

TEMPERATURE

4 5 6

1 2 3

TEST

PRESSURE

.

ENTER

0

3900 LOW HUMIDITY GENERATOR

23.0

THIS DRAWING AND INFORMATION CONTAINED

WITHIN IS PROPRIETARY TO THUNDER SCIENTIFIC

AND CANNOT BE COPIED OR REPRODUCED WITHOUT

.XXX

±.010
±.015

.XX

±.50°

TEST TEMPERATURE (RTD2)

TEST PRESSURE (TR5)

PROPRIETARY NOTICE

SPECIFIC WRITTEN PERMISSION

DRAWN

APPROVED

ISSUED

FISCHER 7/28/1994

BB

GAS VENT

GAS INLET

7/28/1994

7/28/1994GMF

~7.0

3.0

T

MAIN AC
POWER &
SWITCH

REAR

1.5

C

c

i

f

i

n

t

e

S

i

c

n

d

e

DWG. NO.SIZE

T. 404.0W 5

r

M

ic

n

a

h

c

e

D

4

9

3

o

r

ilit

U

t

/

l

a

1

0

9

9

SHEET 1 OF 1

h

u

623 Wyoming S.E. Albuquerque, NM 87123

A

~32.4

p

y

o

r

2.6

a

REV

G

o

n

i

t

NOTES:

1. INTERPRET DRAWING PER ASME Y14.100-2013

2. INTERPRET DIMENSIONS AND TOLERANCES PER ASME Y14.5-2009

3. ALL UNITS ARE INCHES U.N.O.

METHANOL EXPANSION
TANK FILL PORT

TR4

SOL4

TR3

TOP

DWN

REV.

DWF

E

RTD1 ACCESS

TEST TEMPERATURE (RTD2)

TEST PRESSURE (TR5)

MASS FLOW TR2

REVISIONS

DESCRIPTION

Drawn to SW

DATE

8/13/2013

APPROVED

LEFT SIDE

NEXT ASSY

APPLICATION

3900

USED ON

FRONT

PRODUCTION
DESIGNATION

THIRD ANGLE
PROJECTION

39-Z-2

TOLERANCES

.X ±.25

UNLESS NOTED OTHERWISE

±.50°

SUPPLY PRESSURE TR1

SUPPLY PRESSURE

REGULATOR

GAS INLET FILTER

SATURATOR FLUID DRAIN

PROPRIETARY NOTICE

THIS DRAWING AND INFORMATION
CONTAINED WITHIN IS PROPRIETARY
TO THUNDER SCIENTIFIC AND
CANNOT BE COPIED OR REPRODUCED
WITHOUT WRITTEN PERMISSION

DRAWN

CHECKED

ISSUED

FISCHER

4/4/1995

4/4/1995

4/4/1995

RIGHT SIDE

Thunder Scientific Corporation

623 Wyoming S.E. Albuquerque, NM 87123

Component Locations

DWG. NO.

SIZE

A

SCALE:

1 : 16

94D39902

WT.

293.46

SHEET 1 OF 1

REV

E

"A"

CONSOLE PORT

PRINTER PORT

KEYBOARD PORT

DWN

DWF

REV.

E

DESCRIPTION

Drawn to SW

DETAIL "A"

TB2

DATE

8/14/2013

APPROVED

1
2
3

4

5
6
7

LEFT SIDE

NEXT ASSY

APPLICATION

3900

USED ON

DIGITAL I/O PORT

WRITE PROTECT SWITCHES

PRODUCTION
DESIGNATION

THIRD ANGLE
PROJECTION

39-Z-3

TOLERANCES

.X ±.25

UNLESS NOTED OTHERWISE

±.50°

DISPLAY PORT

ANALOG INPUT PORT

ATB (ANALOG TERMINAL BOARD)

PROPRIETARY NOTICE

THIS DRAWING AND INFORMATION
CONTAINED WITHIN IS PROPRIETARY
TO THUNDER SCIENTIFIC AND
CANNOT BE COPIED OR REPRODUCED
WITHOUT WRITTEN PERMISSION

DRAWN

CHECKED

ISSUED

FISCHER

3/31/1995

4/4/1995

4/4/1995

Thunder Scientific Corporation

623 Wyoming S.E. Albuquerque, NM 87123

Cards & Card Cage

DWG. NO.

SIZE

A

SCALE:

1 : 8

95D39903

WT.

SHEET 1 OF 1

REV

E

BUS

DWN

DWF

REV.

D

REVISIONS

DESCRIPTION

Drawn to SW

DATE

8/14/2013

APPROVED

PS1

(POWER SUPPLY)

LCD-INV

(INVERTER BOARD)

LCD

(LIQUID CRYSTAL

DISPLAY)

LCD-CON

(DISPLAY DRIVER BOARD)

SSRB

(SOLID STATE

RELAY BOARD)

TIB

(TERMINAL

INTERFACE BOARD)

CPU

A/D

(ANALOG BOARD)

ATB

(ANALOG TERMINAL

BOARD)

KB

(KEYBOARD)

CONSOLE

PORT

PRINTER

PORT

MEM

(MEMORY BOARD)

NEXT ASSY

APPLICATION

3900

USED ON

PRODUCTION
DESIGNATION

39-Z-4

TOLERANCES

THIRD ANGLE
PROJECTION

.X ±.25

UNLESS NOTED OTHERWISE

±.50°

PROPRIETARY NOTICE

THIS DRAWING AND INFORMATION
CONTAINED WITHIN IS PROPRIETARY
TO THUNDER SCIENTIFIC AND
CANNOT BE COPIED OR REPRODUCED
WITHOUT WRITTEN PERMISSION

DRAWN

CHECKED

ISSUED

FISCHER

3/29/1995

4/4/1995

4/4/1995

Thunder Scientific Corporation

623 Wyoming S.E. Albuquerque, NM 87123

3900 Bus Diagram

DWG. NO.

SIZE

A

SCALE:

N/A

95D39904

WT.

SHEET 1 OF 1

REV

D

DWN

DWF

DWF

REV.

F

G

REVISIONS

DESCRIPTION

Drawn to SW

Added SSR1 for 10 SLPM Option

DATE

8/14/2013

1/19/2015

APPROVED

PLF1

CF2

CN1

1

PS1

3

2

PS2

17

11

10

9

8

7

5

6

4

TB1

16

12

13

15

14

+15 VDC

18

19

20

+5 VDC

-15 VDC

COMMON

COMMON

A0
A1
A2
A3
A4
A5
A6
A7

B0
B1
B2
B3
B4
B5
B6
B7
C0
C1
C2
C3
C4
C5
C6
C7

TIB

SSRB

SSR0

SSR1

SSR2

SSR3

SSR4

SSR5

SSR6

SSR7

+

-

1

2
3
4
5
6
7
8
9
10
11
12
13
14

15
16

CN15

CN14

CN13

H3

(CN31)

24 VDC

COMMON

CN8

SSR10

SOL3

SSR8SSR9

(CN11)

SOL4

(CN12)

CF1

(CN4)

FP1

(CN5)

NEXT ASSY

APPLICATION

C2

(CN6)C1(CN7)

PRODUCTION
DESIGNATION

3900

USED ON

UNLESS NOTED OTHERWISE

THIRD ANGLE
PROJECTION

39-Z-5

TOLERANCES

.X ±.25

±.50°

PROPRIETARY NOTICE

THIS DRAWING AND INFORMATION
CONTAINED WITHIN IS PROPRIETARY
TO THUNDER SCIENTIFIC AND
CANNOT BE COPIED OR REPRODUCED
WITHOUT WRITTEN PERMISSION

DRAWN

CHECKED

ISSUED

FISCHER

3/29/1995

4/13/1995

4/13/1995

SOL2

(CN10)

SOL1
(CN9)

SIDE VIEW

Thunder Scientific Corporation

623 Wyoming S.E. Albuquerque, NM 87123

Electrical Sub Panel Layout

DWG. NO.

SIZE

A

SCALE:

N / A

95D39905

WT.

SHEET 1 OF 1

REV

G

MOV-1

MOV-1

MOV-1

TB1

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

CHASSIS GROUND

L

1

L

1

L

1

L / NEUTRAL

2

L / NEUTRAL

2

L / NEUTRAL

2

L / NEUTRAL

2

L / NEUTRAL

2

L / NEUTRAL

2

+5 VDC

+5 VDC

+5 VDC

+5 VDC

+5 VDC

COMMON

COMMON

COMMON

COMMON

COMMON

CP1

CP2

DWN

DWF

REV.

G

TB2

1

2

3

4

5

6

7

DESCRIPTION

Drawn to SW

-15 VDC

COMMON

+15 VDC

COMMON

+15 VDC

COMMON

+15 VDC

REVISIONS

DATE

8/20/2013

APPROVED

NEXT ASSY

APPLICATION

3900

USED ON

PRODUCTION
DESIGNATION

THIRD ANGLE
PROJECTION

39-Z-6

TOLERANCES

.X ±.25

UNLESS NOTED OTHERWISE

±.50°

PROPRIETARY NOTICE

THIS DRAWING AND INFORMATION
CONTAINED WITHIN IS PROPRIETARY
TO THUNDER SCIENTIFIC AND
CANNOT BE COPIED OR REPRODUCED
WITHOUT WRITTEN PERMISSION

DRAWN

CHECKED

ISSUED

FISCHER

3/29/1995

4/4/1995

4/4/1995

Thunder Scientific Corporation

623 Wyoming S.E. Albuquerque, NM 87123

Terminal Layout

SIZE

A

SCALE:

DWG. NO.

WT.

95S39906

N / AN / A

SHEET 1 OF 1

REV

G

L (N)

2

REVISIONS

DWN

DWF

REV.

G

DESCRIPTION

Drawn to SW

DATE

8/21/2013

APPROVED

CN1

L

1

MOV-1

CBS1

FB1

POWER

MOV-1

TB1

1

+15 VDC
COMMON

PS1 PS2

-15 VDC

+24 VDC
COMMON

+5 VDC

PLF1

COMMON

MOV-1

G

CHASSIS

NEXT ASSY

APPLICATION

3900

USED ON

THIRD ANGLE
PROJECTION

TOLERANCES

.XXX ±.010

UNLESS NOTED OTHERWISE

CHASSIS

THIS DRAWING AND INFORMATION CONTAINED

WITHIN IS PROPRIETARY TO THUNDER SCIENTIFIC

AND CANNOT BE COPIED OR REPRODUCED WITHOUT

±.50°

10

PROPRIETARY NOTICE

SPECIFIC WRITTEN PERMISSION

DRAWN

CHECKED

ISSUED

FISCHER

3/25/1995

4/4/1995

4/4/1995

Thunder Scientific Corporation

623 Wyoming S.E. Albuquerque, NM 87123

AC - DC Power Schematic

DWG. NO.

SIZE

A

SCALE:

95S39907

N / A N / A

WT.

SHEET 1 OF 1

REV

G

CPU

I / O PORT

CONTROL

INPUT

SIDE

SSRB

SSR0

SSR1

SSR2

SSR3

SSR4

SSR5

SSR6

SSR7

TO 26 PIN
CONNECTOR

+5

COM

+

-

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

OUTPUT

SIDE

1

2

3

4

5

6

7

8

9

10

11

PS2 +24 VDC

PS2 COMMON

2

5

9

8

1

4

CN8

CN12

CN11

CN10

CN30

CN29

CN28

DWN

DWF

DWF

CN22

REV.

J

K

CN26

REVISIONS

DESCRIPTION

Drawn to SW

Revised 10 SLPM Option Heaters

SOL5 - SATURATOR

REFRIGERANT

SOLENOID

H2 - SATURATOR

INLET / OUTLET

HEATER

CN32

SOL4

PRESSURE SELECT

SOLENOID

SOL3

SATURATOR

VENT / PURGE

SOLENOID

SOL2

FLUID PUMP

PURGE

SOLENOID

CN31

DATE

9/19/2013

1/20/2015

SATURATOR

TUBE

HEATERS

H3 AUX. EXPANSION

VALVE HEATER

31.2 Ω TOTAL

APPROVED

NEXT ASSY

APPLICATION

3900

USED ON

12

13

14

15

16

THIRD ANGLE
PROJECTION

#2 - #4

TB1

#5 - #10

TB1

TOLERANCES

.XXX ±.010

UNLESS NOTED OTHERWISE

±.50°

CN9

CN5

CN4

PROPRIETARY NOTICE

THIS DRAWING AND INFORMATION CONTAINED

WITHIN IS PROPRIETARY TO THUNDER SCIENTIFIC

AND CANNOT BE COPIED OR REPRODUCED WITHOUT

SPECIFIC WRITTEN PERMISSION

DRAWN

CHECKED

ISSUED

CN27

FISCHER

CF1

CONSOLE FAN

3/31/1995

3/31/1995

3/31/1995

SOL1

GAS SUPPLY

SOLENOID

FP1

FLUID PUMP

Thunder Scientific Corporation

623 Wyoming S.E. Albuquerque, NM 87123

Solid State Relay Module Schematic

DWG. NO.

SIZE

A

SCALE:

95S39908

N / AN / A

WT.

SHEET 1 OF 1

REV

K

TIB

B5

B6

TB1

#2 - #4

PS1

(+5 VDC)

3 4

3 4

1 2

SSR10

TB1

#5 - #10

DWN

DWF

CN6

REV.

F

TB1

#5 - #10

DESCRIPTION

Drawn to SW

CN8

REVISIONS

SATURATOR

HEATER

HLS1

DATE

8/21/2013

APPROVED

H1

R-23 COMPRESSOR

C6

B7

3 4

1 2

SSR8

PS1

(+5 VDC)

NEXT ASSY

APPLICATION

3900

USED ON

1 2

SSR9

CN7

TB1

#5 - #10

CN24

THIRD ANGLE
PROJECTION

THIS DRAWING AND INFORMATION CONTAINED

WITHIN IS PROPRIETARY TO THUNDER SCIENTIFIC

AND CANNOT BE COPIED OR REPRODUCED WITHOUT

TOLERANCES

.XXX ±.010

UNLESS NOTED OTHERWISE

±.50°

C1

SPKR
(ALARM)

PROPRIETARY NOTICE

SPECIFIC WRITTEN PERMISSION

DRAWN

CHECKED

ISSUED

FISCHER

3/30/1995

4/4/1995

4/4/1995

C2

R-134a COMPRESSOR

Thunder Scientific Corporation

623 Wyoming S.E. Albuquerque, NM 87123

Compressor, Heater, Alarm Schematic

DWG. NO.

SIZE

A

SCALE:

N / A

95S39909

WT.

N / A

SHEET 1 OF 1

REV

F

PS2

+24 VDC

COMMON

CN15

8 8

2 2

PS1 (+5 VDC)

SMD-1

Vcc

GND

CW+

REVISIONS

DWN

REV.

DWF

E

BLK

A

YEL

C

A

SM-1

DESCRIPTION

Drawn to SW

NC

SL1
CENTER
POSITION

DATE

8/22/2013

APPROVED

C

GRN

A

TIB

FULL/MICRO STEP

B4

CLOSE PULSE

B0

OPEN PULSE

B2

CENTER POSITION

A0

1 1

4 4

7 7

3 3

NEXT ASSY

APPLICATION

3900

USED ON

CCW+

2P IN+

2P IN-

CW-

CCW-

THIRD ANGLE
PROJECTION

THIS DRAWING AND INFORMATION CONTAINED

WITHIN IS PROPRIETARY TO THUNDER SCIENTIFIC

AND CANNOT BE COPIED OR REPRODUCED WITHOUT

TOLERANCES

.XXX ±.010

UNLESS NOTED OTHERWISE

±.50°

RED

B

WHT

C

B

BLU

B

PROPRIETARY NOTICE

SPECIFIC WRITTEN PERMISSION

DRAWN

CHECKED

ISSUED

FISCHER

3/30/1995

4/4/1995

4/4/1995

Thunder Scientific Corporation

623 Wyoming S.E. Albuquerque, NM 87123

Flow Valve Driver Schematic

DWG. NO.

SIZE

A

SCALE:

95S39910

WT.

N / AN / A

SHEET 1 OF 1

REV

E