Vaisala DM500 User Manual
r
USER'S GUIDE
Vaisala DEWCAP®Precision SAW
Hygromete
DM500
M210205EN-D
PUBLISHED BY
Vaisala Oyj Phone (int.): +358 9 8949 1
P.O. Box 26 Fax: +358 9 8949 2227
FIN-00421 Helsinki
Finland
Visit our Internet pages at http://www.vaisala.com/
© Vaisala 2006
No part of this manual may be reproduced in any form or by any means, electronic or
mechanical (including photocopying), nor may its contents be communicated to a third
party without prior written permission of the copyright holder.
The contents are subject to change without prior notice.
Please observe that this manual does not create any legally binding obligations for
Vaisala towards the customer or end user. All legally binding commitments and
agreements are included exclusively in the applicable supply contract or Conditions of
Sale.
________________________________________________________________________________
Table of Contents
CHAPTER 1
GENERAL INFORMATION............................................................................7
About This Manual...................................................................7
Version Information ............................................................... 7
Feedback............................................................................... 7
Safety......................................................................................... 8
General Safety Considerations ............................................. 8
Product Related Safety Precautions ..................................... 8
ESD Protection...................................................................... 9
Regulatory Compliances.........................................................9
Trademarks.............................................................................12
License Agreement................................................................12
Warranty..................................................................................12
CHAPTER 2
PRODUCT OVERVIEW................................................................................ 13
Product Description...............................................................13
Front Panels............................................................................ 15
Back Panels ............................................................................ 17
Optional Accessories and Spare Parts................................19
Factory Calibration and Service...........................................19
CHAPTER 3
FUNCTIONAL DESCRIPTION.....................................................................21
DM500 Principle of Operation...............................................21
Sensing Element ................................................................. 22
RF-Signal ............................................................................22
Contamination and Chemical Resistance ........................... 23
CHAPTER 4
GENERAL INFORMATION ABOUT SAMPLING AND RESULTS.............25
Gas Sampling .........................................................................25
Measuring in Overpressure...................................................26
The Effect of the Ambient Temperature on Cooling
Capacity...................................................................................27
The Effect of the Liquid Coolant Temperature on Cooling
Capacity...................................................................................28
The Effect of the Sample Gas Flow Rate on Cooling
Capacity and Result Deviation..............................................29
VAISALA ________________________________________________________________________ 1
User's Guide ______________________________________________________________________
CHAPTER 5
INFORMATION ON OPTIONAL PARTS .....................................................31
Optional Heated Gas Tubes...................................................31
Optional External Temperature Sensor................................32
Wetted Materials of the Optional Parts ................................33
CHAPTER 6
SETTING UP FOR OPERATION .................................................................35
Connection of the DMI500 and DMP501 Units.....................35
Swagelok tube fittings' installation instructions ...................36
Connecting the Sample Gas Flow ........................................37
Selecting the Cooling Method...............................................38
Connecting the Cooling Liquid.............................................39
Connecting the Condensation Water Drain Tube ...............40
CHAPTER 7
MEASURING THE DEWPOINT ...................................................................41
Dewpoint Measurement with DM500 ..................................41
More About the Moisture Phases 67 ...................................42
CHAPTER 8
DISPLAYS AND MENUS .............................................................................45
Main View (In Measuring Mode)............................................45
Graphical Display ...................................................................46
Menus and Navigation ...........................................................47
CHAPTER 9
BASIC SETTINGS........................................................................................49
User Interface..........................................................................49
Setting the Language .......................................................... 49
Changing the Shortcut Keys................................................49
Key Click ON/OFF ............................................................... 50
Setting Date and Time............................................................50
Device Information.................................................................51
Reverting Factory Settings....................................................52
CHAPTER 10
DISPLAY SETTINGS....................................................................................53
Display Backlight....................................................................53
Selecting the Quantities and Units.......................................53
Hold/Save Display...................................................................54
Graphic Trend.........................................................................55
Contrast Adjustment..............................................................56
Alarm Sound ...........................................................................56
2 ___________________________________________________________________ M210205EN-D
________________________________________________________________________________
CHAPTER 11
MEASUREMENT SETTINGS.......................................................................59
Automatic Frost Detection .................................................... 59
Forced Freezing......................................................................60
Cooling Method Air/Water.....................................................60
Statistical Filtering.................................................................61
Response Speed ....................................................................62
Pump ON/OFF.........................................................................62
Transient Recovery Time.......................................................63
Setting the Temperature, Pressure, and Flow Values........ 63
CHAPTER 12
SELF DIAGNOSTICS SETTINGS................................................................65
Salt Detection .........................................................................65
Sensor Circuit Check.............................................................66
Cooling Capacity Test............................................................67
Error History........................................................................... 68
CHAPTER 13
RECORDING DATA.....................................................................................69
Data Recording.......................................................................69
Stopping Recording............................................................... 70
Viewing Recorded Data .........................................................70
Checking the Recording Memory Status.............................70
Deleting All Record Files....................................................... 71
CHAPTER 14
OUTPUT INTERFACES...............................................................................73
Serial Communication Settings............................................74
Analog Outputs (Optional) .................................................... 75
Relay Outputs (Optional).......................................................77
CHAPTER 15
CALIBRATIOND AND ADJUSTMENT........................................................81
General About Calibration and Adjustments ...................... 81
Calibration Interval .............................................................. 81
Calibration Laboratory......................................................... 81
Calibrating DM500 Equipped with a Pump ......................... 82
Making an Adjustment........................................................... 82
CHAPTER 16
SERIAL LINE COMMANDS.........................................................................85
Serial Commands................................................................... 85
Output Commands (DMI500).................................................86
R Continuous Output ..................................................... 86
VAISALA ________________________________________________________________________ 3
User's Guide ______________________________________________________________________
S Stopping the Continuous Output.................................87
ADDR Setting the Device Address................................. 87
SEND Outputting One Single Reading ..........................87
INTV Setting the Output Interval .................................... 87
FORM Defining the Output Format ................................ 88
Operational Commands.........................................................91
START Starting the Measurement ................................. 91
STOP Stopping the Measurement .................................91
PUMP Starting/Stopping the Optional Sample Gas Pump91
HEAT Starting/Stopping the Optional Heater................. 92
SALT Enables/Disables the Salt Contamination Detection92
SCAL Starts the Salt Detection Limit Determination Cycle93
PTEST Starts the Cooling Capacity Test ....................... 93
ANAL Starts/Stops the Statistical Filtering ..................... 94
FFROST Enabled/Disables the Automatic Forced
Freezing Procedure........................................................94
Setting Commands.................................................................95
SERI Setting the Serial Communication Parameters..... 95
UNIT Setting the Units....................................................95
TIME Setting the Date and Time....................................96
RSEL Setting the Relays................................................ 96
ASEL Setting the Analog Outputs .................................. 97
AERR Setting the Invalid Output for Analog Channel....98
COOLER Setting the Cooling Method Status ................99
FLOW Setting the Flow Value........................................99
XFLOW Setting the Flow Value Temporarily ...............100
PRES Setting the Pressure..........................................100
XPRES Setting the Pressure Temporarily ...................100
TP Setting the Temperature.........................................101
XTP Setting the Temperature Temporarily ..................101
Adjustments..........................................................................102
CDP Adjusting Dewpoint Temperature (in 4 ... 10 points)102
CTP Adjusting the Dewpoint Temperature (in two points)104
FCAL Adjusting the Flow Meter (in one point) .............105
PCAL Adjusting the Pressure Sensor (in two points)...105
Others....................................................................................106
? Outputting the Device Settings.................................. 106
?? Outputting the Device Settings in POLL-State........106
DEL Deleting the Data Files.........................................106
DIR Outputting List of the Data Files............................106
ECHO Setting the Echo ON/OFF.................................106
ERRS Outputting the Error Messages .........................106
HELP Outputting the Commands.................................107
INIE Reverting the Factory Settings.............................107
SMODE Selecting the Operation Mode .......................107
OPEN & CLOSE Opening and Closing the Lines ........ 108
PLAY Outputting the Data File or History Memory ......108
SCC Sensor Circuit Check........................................... 109
SSC Sensor Status Check ...........................................109
SNUM Outputting the Serial Numbers of DM500 and
DMP501 .......................................................................109
VERS Outputting the Program Name and Version ...... 110
CHAPTER 17
4 ___________________________________________________________________ M210205EN-D
________________________________________________________________________________
MI70 LINK PROGRAM............................................................................... 111
Installation ............................................................................111
Device Name MI70ÙDM500 ................................................111
Displayed Quantities............................................................ 112
Sensing Unit Status .............................................................112
Real-Time Quantities............................................................112
Real-Time Update Interval...................................................112
Chart......................................................................................112
CHAPTER 18
MAINTENANCE ......................................................................................... 113
Cleaning the Sensor.............................................................113
Error Messages ....................................................................115
Technical Support................................................................ 116
Return Instructions..............................................................116
CHAPTER 19
SPECIFICATIONS...................................................................................... 119
Measured Variables..............................................................119
Dewpoint Temperature ................................................ 119
External Temperature (Optional) .................................121
Integrated Pressure (Optional)..................................... 121
Integrated Flow (Optional) ........................................... 121
General..................................................................................121
DMP501 Dewpoint Sensing Unit.................................. 121
Options for DMP501 .................................................... 122
DMI500 User Interface Unit ......................................... 122
Options for DMI500...................................................... 123
Outputs.................................................................................. 123
Electromagnetic Compatibility ...........................................123
Dimensions (in mm)............................................................. 123
APPENDIX A
HUMIDITY THEORY...................................................................................127
Measured and Calculated Results of DM500.....................127
Water Vapor in Air................................................................ 127
Saturation Vapor Pressure..................................................128
Dewpoint Temperature (T
Frost Point Temperature (T
Partial Pressure of Water Vapor (P
) ................................................. 128
d
)...............................................128
f
) .................................129
w
Relative Humidity (RH).........................................................129
Mixing Ratio (x).....................................................................130
Absolute Humidity (a)..........................................................131
Absolute Humidity at NTP (aNTP) ......................................131
Wet Bulb Temperature......................................................... 131
Enthalpy (h)...........................................................................131
VAISALA ________________________________________________________________________ 5
User's Guide ______________________________________________________________________
Humid Air Volume/Dry Air Volume PPM
Effect of Pressure on Dewpoint..........................................132
Using a Condensation Hygrometer....................................132
List of Figures
Figure 1 DMI500 User Interface Unit Front Panel .................................. 15
Figure 2 DMP501 Dewpoint Sensing Unit Front Panel ..........................16
Figure 3 DMI500 User Interface Unit Back Panel...................................17
Figure 4 DMP501 Dewpoint Sensing Unit Back Panel...........................18
Figure 5 DM500 Operating Principle Illusrated....................................... 21
Figure 6 RF-Signal Input/Output Illustrated ............................................22
Figure 7 Effect of Ambient Air Temperature on Lowest Achievable Stable
Sensor Temperature................................................................. 27
Figure 8 Effect of Water Temperature on Lowest Achievable Stable
Sensor Temperature................................................................. 28
Figure 9 Effect of Sample Flow Rate on Lowest Achievable Sensor
Temperature .............................................................................29
Figure 10 Effect of Sample Flow Rate on Dewpoint Measurement at -
60 ºC.........................................................................................29
Figure 11 Mechanical Dimensions (in mm) for Optional Temperature
Sensor ......................................................................................32
Figure 12 Standard 6 mm Swagelok Tube Fitting with the Elbow
Connector in the DMP501 Back Panel.....................................36
Figure 13 ¼" Swagelok Adapter Fitting Connected to the Standard
Swagelok 6 mm Connector ......................................................37
Figure 14 DMP501 Back Panel, Connectors for Sample Gas.................. 37
Figure 15 DMP501 Back Panel, Connectors for Cooling Liquid...............39
Figure 16 Main View Display ....................................................................45
Figure 17 DM500 Graphical Display.........................................................46
Figure 18 DM500 Menus and Displays.....................................................47
Figure 19 DMI500 User Interface Unit Information...................................51
Figure 20 DMP501 Dewpoint Sensing Unit Information ........................... 51
Figure 21 DMI500 User Interface Unit Back Panel (Same as Figure 3)...73
Figure 22 Gas Flow Rate from the Humidity Generator ........................... 82
Figure 23 Dewpoint Temperature Measurement Repeatability..............120
Figure 24 Dewpoint Temperature Measurement Response Time .........120
Figure 25 Partial Pressure of Water Vapor Over Water and Ice ............129
Figure 26 Water Vapor Saturation Curves..............................................130
...........................132
v
List of Tables
Table 1 Manual Revisions ....................................................................... 7
Table 2 4-Wire Connection....................................................................74
Table 3 2-Wire Connection....................................................................74
6 ___________________________________________________________________ M210205EN-D
Chapter 1 ________________________________________________________ General Information
CHAPTER 1
GENERAL INFORMATION
This chapter provides general notes for the product.
About This Manual
This manual contains instructions for performing accurate dewpoint
measurements with Precision SAW Hygrometer DM500.
Version Information
Table 1 Manual Revisions
Manual Code Description
M210205EN-A 1st version, August 2001
M210205EN-B 2nd version, April 2002
M210205EN-C 3rd version, February 2004
M210205EN-D 4th version, May 2005
Feedback
Vaisala Customer Documentation Team welcomes your comments
and suggestions on the quality and usefulness of this publication. If
you find errors or have other suggestions for improvement, please
indicate the chapter, section, and page number. You can send
comments to us by e-mail: manuals@vaisala.com
VAISALA ________________________________________________________________________ 7
User's Guide ______________________________________________________________________
Safety
General Safety Considerations
Throughout the manual, important safety considerations are
highlighted as follows:
WARNING
CAUTION
NOTE
Warning alerts you to a serious hazard. If you do not read and follow
instructions very carefully at this point, there is a risk of injury or
even death.
Caution warns you of a potential hazard. If you do not read and
follow instructions carefully at this point, the product could be
damaged or important data could be lost.
Note highlights important information on using the product.
Product Related Safety Precautions
The DM500 Precision SAW Hygrometer delivered to you has been
tested for safety and approved as shipped from the factory. Note the
following precautions:
WARNING
CAUTION
8 ___________________________________________________________________ M210205EN-D
Ground the product, and verify outdoor installation grounding
periodically to minimize shock hazard.
Do not modify the unit. Improper modification can damage the
product or lead to malfunction.
Chapter 1 ________________________________________________________ General Information
ESD Protection
Electrostatic Discharge (ESD) can cause immediate or latent damage
to electronic circuits. Vaisala products are adequately protected
against ESD for their intended use. However, it is possible to damage
the product by delivering electrostatic discharges when touching,
removing, or inserting any objects inside the equipment housing.
To make sure you are not delivering high static voltages yourself:
- Handle ESD sensitive components on a properly grounded and
protected ESD workbench. When this is not possible, ground
yourself to the equipment chassis before touching the boards.
Ground yourself with a wrist strap and a resistive connection cord.
When neither of the above is possible, touch a conductive part of
the equipment chassis with your other hand before touching the
boards.
- Always hold the boards by the edges and avoid touching the
component contacts.
Regulatory Compliances
Tämä laite on pienjännitedirektiivin 73/23/ETY mukainen !
- Lue käyttöopas kokonaan ja huolellisesti ennen kuin käytät laitetta.
- Ennen kuin liität laitteeseen virran, varmista, että virtalähteen syöttöjännite on sama kuin laitteeseen liitetyssä
tuotetietokilvessä mainittu käyttöjännite.
- Kytke verkkojohto maadoitettuun pistorasiaan !
- DMP501- ja DMI500-laitteiden sisällä ei ole käyttäjän huollettavissa olevia osia. Vahingollisen jännitteen
aiheuttamien vahinkojen välttämiseksi laitetta ei saa avata kuin Vaisalan valtuuttama huoltohenkilöstö.
- Älä käytä laitetta yhdessä syttyvien, voimakkaasti reagoivien tai myrkyllisten kaasujen kanssa. Varmista
tuuletuksen riittävyys ennen laitteen käyttämistä muiden kaasujen kuin ilman kanssa.
- Älä kokoa laitetta ympäristössä, jossa järjestelmässä poistuva tiivistynyt vesi saattaa aiheuttaa vaaratilanteita
(esimerkiksi korkeajännitteisten virtalähteiden päällä).
- Kun lämmitintoiminto on käytössä, älä kosketa anturikammion kuumaa suojusta. Käytä hansikkaita, kun irrotat
suojuksen.
Den här produkten uppfyller lågspänningsdirektivet (73/23 EEC) !
- Läs igenom hela användarhandboken noga innan du använder produkten.
- Innan du ansluter produkten i vägguttaget, bör du kontrollera att nätspänningen överensstämmer med den
driftsspänning, som anges på typskylten som finns på produkten.
- Det finns inga delar inuti DMP501- eller DMI500-mätaren, som ska underhållas av användaren. För att undvika
att säkerhetsrisker uppstår med farlig spänning får höljet aldrig avlägsnas, utom av auktoriserad servicepersonal
från Vaisala.
VAISALA ________________________________________________________________________ 9
User's Guide ______________________________________________________________________
- Anslut inte brandfarliga, mycket reaktiva eller giftiga gaser till instrumentet. Se till att ventilationen är tillräcklig
vid användning av andra gaser än luft.
- Sätt inte samman instrumentet i en lokal där kondensvatten som droppar ut ur systemet kan orsaka en farlig
situation, till exempel ovanpå högspänningsutrustning.
- Rör inte vid det heta locket på mätprobens kammare med fingrarna när uppvärmningsfunktionen har aktiverats.
Använd handskar när du ska ta av locket.
Dieses Produkt entspricht der Niederspannungsrichtlinie (73/23 EWG) !
- Lesen Sie die Bedienungsanleitung vor Verwendung des Geräts sorgfältig und vollständig durch.
- Vergewissern Sie sich vor dem Anschließen an eine Steckdose, dass die Netzspannung der Betriebsspannung
entspricht, die auf dem Typenschild des Produkts angegeben ist.
- Die Systeme DMP501 und DMI500 enthalten keine vom Benutzer zu wartenden Teile. Zur Vermeidung von
Sicherheitsrisiken durch gefährliche Spannungen darf das Gehäuse nur von befugtem Vaisala-Wartungspersonal
geöffnet werden.
- Halten Sie das Gerät von entflammbaren, hoch reaktiven und giftigen Gasen fern. Sorgen Sie bei Verwendung
anderer Gase als Luft für ausreichende Belüftung
- Montieren Sie das Gerät nicht an Orten, an denen aus dem System tropfendes Kondenswasser eine Gefahr
darstellen kann, wie z. B. über Hochspannungversorgungen.
- Bei aktivierter Heizfunktion darf der heiße Deckel der Sensorkammer nicht mit bloßen Händen angefasst
werden. Verwenden Sie zum Abnehmen des Deckels Handschuhe.
Ce produit est conforme à la Directive relative à la Basse Tension (73/23 EEC) !
- Bien lire le guide de l'utilisateur dans son intégralité avant utilisation.
- Avant de brancher dans une prise, vérifier que la tension électrique de fonctionnement correspond à la tension de
fonctionnement mentionnée sur la plaque signalétique attachée au produit.
- Le DMP501 ou le DMI500 ne contiennent pas de pièces susceptibles d'être réparées par l'utilisateur. Afin
d'éviter tout danger lié à la tension électrique, le boîtier ne peut être ouvert que par un employé de maintenance
autorisé de Vaisala .
- Ne pas raccorder à l'instrument tous gaz inflammables, réactifs ou toxiques. Veiller à une ventilation correcte
lors de l'utilisation de gaz différents de l'air.
- Ne pas assembler l'instrument dans un endroit où de l'eau condensée s'échappant du système pourrait provoquer
un danger, par exemple, au-dessus d'une alimentation en haute tension.
- Lorsque la fonction de réchauffage est activée, ne pas toucher le couvercle chaud de la chambre du capteur à
mains nues. Porter des gants pour détacher le couvercle.
Questo prodotto è conforme alla Direttiva sulla Bassa Tensione (73/23 EEC) !
- Si prega di leggere attentamente e completamente la guida per l'utente prima dell'uso.
- Prima del collegamento a una presa di corrente, controllate che il vostro voltaggio operativo corrisponda al
voltaggio operativo specificato nella targhetta indicatrice del prodotto.
- Il DMP501 o il DMI500 non contengono al loro interno parti utilizzabili dall'utente. Per evitare rischi alla
sicurezza con un voltaggio pericoloso, il coperchio non deve essere aperto se non dal personale autorizzato
Vaisala.
- Non collegate gas infiammabili, altamente reattivi o tossici allo strumento. Assicurate una ventilazione adeguata
quando gas diversi dall'aria vengono usati.
10 __________________________________________________________________ M210205EN-D
Chapter 1 ________________________________________________________ General Information
- Non posizionate lo strumento in un luogo dove l'acqua condensata che fuoriesce dal sistema potrebbe causare un
pericolo, come su alimentatori elettrici ad alto voltaggio.
- Quando la funzione di riscaldamento è attiva, non toccate a mani nude il tappo caldo della camera di
misurazione. Si prega di usare dei guanti per togliere il tappo.
Este producto cumple con la Directiva sobre baja tensión (73/23 CEE) !
- Lea todo el manual de usuario atentamente antes de utilizar el producto.
- Antes de enchufarlo a un conector, compruebe que el voltaje operativo corresponde al que se menciona en el tipo
de placa que se adjunta al producto.
- En DMP501 y en DMI500 no existen partes que puedan resultar prácticas para el usuario. Para evitar que se
produzcan accidentes debidos a tensiones peligrosas, únicamente el personal del servicio autorizado de Vaisala
podrá abrir la carcasa.
- No conecte al instrumento gases tóxicos, muy reactivos o inflamables. Asegúrese de que la ventilación es la
adecuada al utilizar gases que no sean aire.
- No monte el instrumento en una ubicación donde el vapor del agua condensada pueda provocar algún peligro
como, por ejemplo, en la parte superior de una fuente de alimentación de alto voltaje.
- Cuando se activa la función del calentador, no toque la tapa caliente de la cámara del sensor con las manos sin
protección. Utilice guantes cuando vaya a quitar la tapa.
Dette produkt over direktivet om svagstrøm (73/23 EEC) !
- Læs hele brugervejledningen omhyggeligt, før du tager enheden i brug.
- Før du tilslutter enheden til en stikkontakt, skal du kontrollere, at den lokale spænding svarer til den spænding,
der er angivet på pladen med produktoplysninger.
- Der er ingen dele inde i DMP501 eller DMI500, som kan efterses af brugeren. Med henblik på at undgå risiko
for skader, er delene med farlig spænding afdækket, og kabinettet på må kun fjernes af autoriserede Vaisalaserviceteknikere.
- Undgå, at brændbare, højreaktive og giftige luftarter kommer i nærheden af enheden. Sørg for tilstrækkelig
udluftning, når der benyttes andre luftarter end almindelig luftluft.
- Undgå at montere enheden et sted, hvor kondenseret vand kan dryppe ud af systemet og forårsage skader, f.eks.
over et stærkstrømsstik.
- Når varmefunktionen er aktiveret, skal du undgå at berøre topdækslet på sensorkammeret med bare hænder.
Brug handsker, når du tager dækslet af.
Dit product voldoet aan de La agspanningsrichtlijn (73/23 EEC) !
- Lees de volledige gebruikershandleiding aandachtig door voordat u het apparaat in gebruik neemt.
- Voordat u het apparaat op een stopcontact aansluit, controleert u of de plaatselijke bedrijfsspanning overeenkomt
met de bedrijfsspanning die wordt vermeld op het typeplaatje dat op het product is bevestigd.
- Er bevinden zich geen onderdelen in de DMP501 of DMI500 die door de gebruiker kunnen worden
onderhouden. Om veiligheidsrisico's als gevolg van gevaarlijke spanningsniveaus te voorkomen, mag de
behuizing alleen worden geopend door bevoegd onderhoudspersoneel van Vaisala.
- Sluit geen brandbare, sterk reactieve of giftige gassen aan op het instrument. Zorg voor voldoende ventilatie
wanneer u met andere gassen dan lucht werkt.
- Monteer het instrument niet op een locatie waar condenswater dat uit het systeem druppelt tot een gevaarlijke
situatie kan leiden, zoals boven op voedingseenheden met hoge spanning.
VAISALA _______________________________________________________________________ 11
User's Guide ______________________________________________________________________
- Raak het hete kapje van de sensorbehuizing niet met blote handen aan als de verwarmingsfunctie is geactiveerd.
Maak het kapje alleen los met handschoenen aan.
Trademarks
Microsoft®, Windows®, and Windows NT® are registered
trademarks of Microsoft Corporation in the United States and/or other
countries.
License Agreement
All rights to any software are held by Vaisala or third parties. The
customer is allowed to use the software only to the extent that is
provided by the applicable supply contract or Software License
Agreement.
Warranty
For certain products Vaisala normally gives a limited one-year
warranty. Please observe that any such warranty may not be valid in
case of damage due to normal wear and tear, exceptional operating
conditions, negligent handling or installation, or unauthorized
modifications. Please see the applicable supply contract or Conditions
of Sale for details of the warranty for each product.
12 __________________________________________________________________ M210205EN-D
Chapter 2 __________________________________________________________ Product Overview
CHAPTER 2
PRODUCT OVERVIEW
This chapter introduces the features and advantages of Precision SAW
Hygrometer DM500.
Product Description
DM500 is a high accuracy dewpoint temperature measuring
instrument capable of measuring dewpoints down to -75 ºC with an
accuracy of ± 0.2 ºC.
The DM500 system consists of the user interface unit DMI500 and the
dewpoint sensing unit DMP501. Four of the following quantities can
be displayed at a time:
- Dewpoint/frostpoint T
on page 128.
- Dewpoint T
- Partial water vapour pressure P
- Humid air volume/dry air volume H2O (ppmv)
- Relative humidity RH (%)
- Wet-bulb temperature Tw (ºC or ºF)
- Absolute humidity a (g/m3 or gr/ft3)
- Mixing ratio x (g/kg or gr/lb)
(ºC or ºF)
d
(ºC or ºF), more about dewpoint/frostpoint
d/f
(mbar)
w
- Enthalpy h (kJ/kg or btu/lb)
- Difference of T and T
- Temperature T (ºC or ºF)
- Pressure P (bar, hPa, psi, torr)
VAISALA _______________________________________________________________________ 13
T (ºC or ºF)
d/f
User's Guide ______________________________________________________________________
- Air flow rate flow (slpm, scfh)
The DM500 system includes two packages including the following
parts:
DMI500
- DMI500 user interface unit
- Serial cable for EIA-232 (RS232)
- CD-Rom including MI70 Link software; to transfer logged data to
your PC
- Power cable (according to the customer's requirement)
DMP501
- DMP501 dewpoint sensing unit
- Swagelok spare tube fittings for 1/4" tubes for the sample gas line
(to replace default tube fittings (6 mm)
- Allen key; to remove the sensor cap and to adjust the sample flow.
- Water tubing for the condense water outlet
14 __________________________________________________________________ M210205EN-D
Chapter 2 __________________________________________________________ Product Overview
Front Panels
Figure 1 DMI500 User Interface Unit Front Panel
The following numbers refer to Figure 1 above:
1 = Mains switch . Press to turn the device on/off.
2 = Configurable softkeys . Press down to activate the menu
function shown beside the button.
3 = Arrow keypad ►. Press any of the arrow buttons to open
path for the menus. In the menus, you can navigate with
arrow buttons. Up and down arrows for moving in the menu,
right-pointing arrow for selecting menu item, left-pointing
arrow for returning to previous menu.
4 = Numeric keypad. Numerical input can be given with the
number keypad.
VAISALA _______________________________________________________________________ 15
User's Guide ______________________________________________________________________
Figure 2 DMP501 Dewpoint Sensing Unit Front Panel
The following numbers refer to Figure 2 above:
NOTE
1 = Power/data cable; connect to the back panel of the DMI500.
2 = Allen screw for adjusting the sample flow.
3 = Sensor cup; three Allen screws to open the cup for sensor
cleaning.
Warranty is void if DMP501 or DMI500 case is opened by the user!
16 __________________________________________________________________ M210205EN-D
Chapter 2 __________________________________________________________ Product Overview
Back Panels
1
C NO NC
REL 1
6
Figure 3 DMI500 User Interface Unit Back Panel
The following numbers refer to Figure 3 above:
1 = Relay outputs (optional)
2 = Serial port (EIA-232, RS232 for Terminal/MI70-link
3 = Connection to DMP501
4 = Mains cable
5 = RS485 and LonWorks-port (optional)
6 = Analog outputs (optional)
C NO NC
REL 2
5
2
3
4
VAISALA _______________________________________________________________________ 17
User's Guide ______________________________________________________________________
3
4
2
1
Figure 4 DMP501 Dewpoint Sensing Unit Back Panel
5
6
7
8
9
NOTE
The following numbers refer to Figure 4 above:
1 = Water In (WI)
2 = Gas In (GI)
3 = Connection to DMI500
4 = Relay for heated sample lines
5 = Water Out (WO)
6 = Temperature sensor connection (optional)
7 = Service switch 4: Adjustment enable switch
8 = Gas Out (GO)
9 = Serial port EIA-232, RS232
The DM500 shall always be operated in horizontal position or in
position where the device is supported by the handle, see picture on
page 125.
18 __________________________________________________________________ M210205EN-D
Chapter 2 __________________________________________________________ Product Overview
Optional Accessories and Spare Parts
Description Order code
Accessories
Rack mounting kit DM500RMP
Portability kit DM500PAK
Extension cable 2.5 m DM500ECS
Extension cable 10 m DM500ECL
Mains EURO 6543
Mains UK 210548
Mains US/Japan 210547
Mains AUS 210619
Spare Parts
PTFE coated O-ring at gas inlet 210493
Factory Calibration and Service
WARNING
Please note that there are no user-serviceable parts inside the
DMP501 or DMI500. To avoid safety risks with hazardous voltage
or hazardous energy, the enclosures shall not be opened except by
authorized Vaisala service personnel.
NORTH AMERICAN SERVICE CENTER
Vaisala Inc., 100 Commerce Way, Woburn, MA 01801-1068, USA.
Phone: +1 781 933 4500, Fax +1 781 933 8029
Email: us-customersupport@vaisala.com
EUROPEAN SERVICE CENTER
Vaisala Instruments Service, Vanha Nurmijärventie 21 FIN-01670
Vantaa, FINLAND.
Phone: +358 9 8949 2758, Fax +358 9 8949 2295
E-mail: instruments.service@vaisala.com
ASIAN SERVICE CENTER
Vaisala KK, 42 Kagurazaka 6-Chome, Shinjuku-Ku, Tokyo 162-0825,
JAPAN.
Phone: +81 3 3266 9611, Fax +81 3 3266 9610
E-mail: aftersales.asia@vaisala.com
www.vaisala.com
VAISALA _______________________________________________________________________ 19
User's Guide ______________________________________________________________________
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20 __________________________________________________________________ M210205EN-D
Chapter 3 ______________________________________________________ Functional Description
CHAPTER 3
FUNCTIONAL DESCRIPTION
This chapter describes the functionality of the product.
DM500 Principle of Operation
DM500 is an automatic, continuously controlling condensation
hygrometer designed to measure dewpoint temperatures from -75 ºC
to +60 ºC, depending on the model. The system consists of the
DMP501 dewpoint sensing unit and the DMI500 user interface unit.
The measured gas flows through the sensing unit, where it contacts a
temperature controlled quartz surface. The quartz surface is monitored
for the presence of condensation. The presence or absence of
condensation is sensed using surface acoustic wave (SAW)
technology. In the measuring mode, the temperature of the quartz
surface is varied until condensation exists in equilibrium. Temperature
of the sensor element is measured with a temperature sensor (1/3 DIN
B, Pt100, 4-wire) bonded on the backside of the quartz substrate. This
measured value is used to accurately output the dew/frostpoint
temperature.
Figure 5 DM500 Operating Principle Illusrated
VAISALA _______________________________________________________________________ 21
User's Guide ______________________________________________________________________
Sensing Element
The DEWCAP® SAW sensor, as used in the condensation
hygrometer, integrates the cooled surface (where condensation forms)
with the detection mechanism in one element. The element consists of
a transmitting and a receiving antenna photolithographically patterned
on a single mechanically very durable crystal quartz chip.
RF-Signal
A radio frequency (RF) signal fed to the transmitting antenna is
converted to a micromechanical wave. The mechanical wave
propagates along the sensing element surface to the receiving antenna,
where the mechanical wave is re-converted to a RF-signal. As the
wave propagates at the sensor surface only, it is very sensitive to
condensation in contact with the surface.
The presence of liquid condensation on the element alters the
signature in a repeatable way. The freezing of the condensation on the
element causes a distinctly different signal change, thus enabling the
determination of whether dew or frost is on the element.
Figure 6 RF-Signal Input/Output Illustrated
Analysis of the received wave in terms of frequency and amplitude
provides the information required to control the element's temperature
in such a way that a thin layer of dew or frost remains in equilibrium
on the element. Additionally, analysis can determine the presence or
absence of hygroscopic contaminants on the element.
Hygroscopic dirt like salt is a common source of error in conventional
dewpoint measurement techniques. The DEWCAP? sensor can detect
the presence of salts on the sensor surface. The salt sensing selfdiagnostics can be turned on/off by the user.
22 __________________________________________________________________ M210205EN-D
Chapter 3 ______________________________________________________ Functional Description
Contamination and Chemical
Resistance
The DM500 operates reliably even with substantial particulate
contamination on the sensing element. Analysis of frequency and
impedance makes it possible to distinguish between frost and dew and
to give warning of hygroscopic contaminants on the detector.
Use of a quartz wafer as a sensor substrate results in excellent
resistance to aggressive chemicals. Wetted parts inside the DMP501
dewpoint sensing unit are limited to stainless steel, silicone, tantalum,
quartz, Vectra® (Liquid Crystal Polyester).
Vectra and silicone parts as well as those optional components that
have water-absorbing materials are located downstream from the
active area of the sensor thus not disturbing the measurement
especially in low dewpoints.
VAISALA _______________________________________________________________________ 23
User's Guide ______________________________________________________________________
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24 __________________________________________________________________ M210205EN-D
Chapter 4 _________________________________ General Information About Sampling and Results
CHAPTER 4
GENERAL INFORMATION ABOUT
SAMPLING AND RESULTS
This chapter provides you with useful information concerning gas
sampling and the effects that different parameters have on the
measurement results.
Gas Sampling
When measuring low dewpoints, all installations must comply with
the strict requirements. Clean environment is always beneficial for
humidity measurements, but this is especially critical at very low
humidities. It is important to use high quality stainless steel tubes
(electropolished), particularly clean and dry. Contamination has often
a hygroscopic effect. Attention must be paid to correct and tight gas
connections. The ambient temperature and the temperature of all parts
of the sampling pathway must be kept above the dewpoint to avoid
condensation.
The following recommendations shall be taken into account when
measuring in very dry environments.
- Minimize the number of connections to avoid leaks
- Ensure that flow rate is adequate
- Avoid dead ends as they cannot be flushed easily
- The temperature of the gas line components must never lie under
the dewpoint of the sample gas, as this leads to condensation and
false results
VAISALA _______________________________________________________________________ 25
User's Guide ______________________________________________________________________
- Sample tubing shall be as short as possible, the surface area should
be minimized by using the tubing with the smallest diameter that
the flow conditions shall permit
- Surface finishing of wetted surfaces is important, polished or
electropolished steel is recommended for best results
- Avoid hygroscopic materials in the sampling lines, use stainless
steel membranes instead of rubber membranes
- Choose impermeable materials to avoid inward diffusion of
moisture through sampling tubes and enclosures, such impermeable
materials include high quality stainless steel and metals. Avoid
PVC or nylon tubes !
- PTFE (Teflon) tubes are not suitable for dewpoints below -40 ºC.
Measuring in Overpressure
When sampling in pressurized processes, the pressure difference
between the gas inlet and outlet ensures gas flow to the sensor.
However, please take into account the following:
- The dewpoint is measured always in the actual pressure. The
pressure is released at the flowmeter valve after the sensor
chamber. When measuring at overpressure, it must be taken into
account that the volume flow rate decreases under pressure,
whereas mass flow rate remains constant.
- The pressure ranges of the optional parts are:
- Integrated pressure sensor: 0...2 bar or 0...20 bar
- Integrated flow sensor: 1.7 bar
26 __________________________________________________________________ M210205EN-D
Chapter 4 _________________________________ General Information About Sampling and Results
The Effect of the Ambient Temperature on
Cooling Capacity
The cooling capacity of the sensor is dependent on the cooling air
temperature, as shown in Figure 7. In general, the cooler the ambient
air is, the lower dewpoint can be reached. By using air as a cooling
medium, the lowest normally achievable dewpoint is about -50 ºC.
When measuring lower dewpoint, water cooling must be used.
Recommended air temperature: 10...40 ºC (50...104 ºF), depending on
the measured dewpoint.
Water cooling is recommended when measuring dewpoints > +40 ºC
(+104 ºF).
Figure 7 Effect of Ambient Air Temperature on Lowest
Achievable Stable Sensor Temperature
VAISALA _______________________________________________________________________ 27
User's Guide ______________________________________________________________________
The Effect of the Liquid Coolant Temperature
on Cooling Capacity
The cooling capacity of the sensor is dependent on the cooling water
temperature, as shown in Figure 8. Recommended water temperature:
< 15 ºC (50 ºF).
Figure 8 Effect of Water Temperature on Lowest Achievable
Stable Sensor Temperature
Sample gas flow in the above Figure 8 1.0 slpm; T
flow 5 l/min.
23 ºC; water
amb
28 __________________________________________________________________ M210205EN-D
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