Vaisala HMT360Series User Manual

HMT360 Series Transmitters

for Hazardous Areas

USER'S GUIDE

M010056EN-D

May 2004

Vaisala __________________________________________________________________________ 2

PUBLISHED BY

Vaisala Oyj Phone (int.): ([phone]
P.O. Box 26 Fax: [phone]
FIN-00421 Helsinki
Finland

Visit our Internet pages at http://www.vaisala.com/

© Vaisala 2004

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.

Table of Contents

CHAPTER 1

GENERAL INFORMATION ............................................................................ 6

Safety.........................................................................................6

ESD Protection...................................................................... 6

Version Information ................................................................. 7

Warranty .................................................................................... 7

CHAPTER 2

GENERAL ...................................................................................................... 8

Output quantities...................................................................... 8

Probe options ...........................................................................8

Maintenance.............................................................................. 9

Compliance with the requirements ...................................... 10

European requirements.......................................................10

US requirements (FM).........................................................10

Canadian requirements (CSA) ............................................ 10

Australian requirements (TestSafe) ....................................10

CHAPTER 3

INSTALLATION............................................................................................ 11

General instructions .............................................................. 11

Mounting the probe cable in gas group IIC spaces............. 11

Selecting a place for the transmitter ................................... 11

Temperature differences ..................................................... 12

Checking the temperature reading...................................... 12

Mounting the transmitter ....................................................... 13

Mounting the probes.............................................................. 14

The HMP362 - small pressure-tight probe .......................... 14

The HMP363 probe for confined spaces ............................ 15

The HMP365 probe for high temperatures ......................... 16

HMP364 for pressurized spaces ......................................... 16

The HMP368 probe for measuring humidity in pressurized

pipelines or moisture in liquids ............................................ 19

Installing the probe through the ball valve assembly ..........21

CHAPTER 4

ELECTRICAL CONNECTIONS ................................................................... 23

Installation in hazardous locations ......................................24

US and Canadian requirements.......................................... 24

European requirements....................................................... 24

Maximum load calculation for the barrier............................ 24

HMT360 connected to a galvanic isolator............................ 25

HMT360 connected to a zener barrier .................................. 26

Examples of connections ...................................................... 27

Grounding ............................................................................... 28

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Vaisala __________________________________________________________________________ 4

CHAPTER 5

OPERATION ................................................................................................. 29

HMT360 with display ..............................................................29

HMT360 without display......................................................... 29

Dip switch functions ..............................................................30

CHAPTER 6

OPERATION ERRORS ................................................................................32

Cleaning the sensor from glycol in a natural gas

application...............................................................................32

CHAPTER 7

DISPLAY/KEYPAD COMMANDS................................................................34

Setting the pressure for calculations ...................................34

Selecting the output quantities ............................................. 35

Upper half of the display.................................................35

Lower half of the display.................................................35

Selecting the analog outputs ................................................35

Scaling the analog outputs.................................................... 37

CHAPTER 8

SERIAL INTERFACE ...................................................................................38

Serial communication settings .............................................38

Selecting the analog outputs ................................................39

Scaling the analog outputs.................................................... 40

Adjustment commands..........................................................40

Relative humidity adjustment ..............................................40

Temperature adjustment .....................................................41

Analog output calibration .....................................................41

Output commands ..................................................................42

Testing the analog outputs ..................................................42

Outputting the measurement values ...................................42

Activating a continuous output ............................................42

Stopping the continuous output...........................................43

Setting the output interval.................................................... 43

Setting the ambient pressure for calculations ....................43

CHAPTER 9

MEASURING AT OVERPRESSURE ...........................................................44

CHAPTER 10

CALIBRATION AND ADJUSTMENT...........................................................45

Calibration interval .................................................................45

Factory calibration and adjustment......................................45

Calibration and adjustment by the user ............................... 45

Calculating the correspondence of current values and

output quantities.....................................................................47

Relative humidity calibration................................................. 48

Automatic two-point calibration (only with HMT360 with

display) ................................................................................48

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Vaisala __________________________________________________________________________ 5

Manual calibration ...............................................................50

Low end adjustment ....................................................... 50

High end adjustment (two-point calibration) .................. 50

Temperature calibration in one point................................... 51

CHAPTER 11

SPECIFICATIONS........................................................................................ 52

Performance ........................................................................... 52

Calculated variables available (typical ranges).............. 53

Outputs.................................................................................... 54

Classification with current outputs ...................................... 54

General .................................................................................... 55

Probes ..................................................................................... 56

Options and accessories....................................................... 56

ACCURACIES OF THE CALCULATED VARIABLES (NOT VALID WITH

HMT360 FOR NATURAL GAS) ................................................................... 57

APPENDIX 1: DIMENSIONS ....................................................................... 59

HMT361............................................................................... 59

HMP362 .............................................................................. 59

HMP363 .............................................................................. 60

HMP364 .............................................................................. 60

HMP365 .............................................................................. 60

HMP368 .............................................................................. 60

APPENDIX 2: WIRING FOR INTRINSICALLY SAFE OPERATION, FM ...63

APPENDIX 3: WIRING FOR INTRINSICALLY SAFE OPERATION, CSA. 64

CERTIFICATES............................................................................................ 65

General Information _________________________________________________________________

Vaisala __________________________________________________________________________ 6

CHAPTER 1

GENERAL INFORMATION

Safety

Throughout the manual, important safety considerations are
highlighted as follows:

WARNING

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

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

Note highlights important information on using the product.

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

General Information _________________________________________________________________

Vaisala __________________________________________________________________________ 7

the equipment chassis with your other hand before touching the

boards.

- Always hold the boards by the edges and avoid touching the
component contacts.

Version Information

Table 1 Manual Revisions

Manual Code Description

U336en-1.1 1st version, March 1999
M010056en-A 2nd version, January 2001
M010056en-B 3rd version, March 2002
M010056en-C 4th version, November 2002
M010056EN-D 5th version, May 2004

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.

General ___________________________________________________________________________

Vaisala __________________________________________________________________________ 8

CHAPTER 2

GENERAL

The HMT360 series transmitters are microprocessor based two-wire
transmitters for measuring relative humidity and temperature in
hazardous areas requiring EX classification. Connect the transmitter
always via galvanic isolators or zener barriers in hazardous
environments.

Output quantities

The transmitter has a local display and two output current channels.
The available quantities are described in Table 2 on page 35.

Probe options

The HMT360 transmitter series has various options for transmitter
units, sensor heads and cable lengths (2.5 and 10 m). The available
probe types are the following:

HMP361 HMP362 HMP363 HMP364 HMP365 HMP368

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Vaisala __________________________________________________________________________ 9

HMP361: probe for wall mounting
HMP362: probe for pressurized spaces up to 167 bars
HMP363: probe head (∅ 13.5 mm) for tight spaces.
HMP364: probe for pressurized spaces up to 100 bars.
HMP365 probe for high temperatures up to 180°C
HMP368 probe for installations in pressurized pipelines

up to 40 bars; pressure tight sliding clasp nut

Maintenance

The transmitter's electronics unit can be removed and replaced in the
field, as well as the probe; see page 44 for detailed information.

All other maintenance is performed at the factory. If a transmitter is
damaged, contact Vaisala or Vaisala distributor and send the
instrument to the addresses below:

Please, include a short description of the fault and the date and place
of purchase.

NORTH AMERICAN SERVICE CENTER
Vaisala Inc., 100 Commerce Way, Woburn, MA 01801-1068, USA.

Phone: [phone], Fax [phone]
Email: [e-mail]

EUROPEAN SERVICE CENTER
Vaisala Instruments Service, Vanha Nurmijärventie 21 FIN-01670 Vantaa,

FINLAND. Phone: [phone], Fax [phone]
E-mail: [e-mail]

ASIAN SERVICE CENTER
Vaisala KK, 42 Kagurazaka 6-Chome, Shinjuku-Ku, Tokyo 162-0825, JAPAN.

Phone: [phone], Fax [phone]
E-mail: [e-mail]

www.vaisala.com

General ___________________________________________________________________________

Vaisala _________________________________________________________________________ 10

Compliance with the requirements

European requirements

EU directive 94/9/EC (ATEX 100a)
Standards EN 50014 and EN 50020
Standard EN 50284 for apparatus of equipment group II, category 1 G
(intended for hazardous locations)
Marking EEx ia IIC T4: at temperature range -20...+60 °C and
pressure range 0.8...1.1 bar.

US requirements (FM)

FM approved for Classes I, II & III, Division 1, Groups A, B, C, D, E,
F & G and Division 2, Groups A, B, C, D, F and G. Intrinsically safe
when connected as shown in Appendix 2.

Canadian requirements (CSA)

CSA approved for Class I, Division 1 and 2, Groups A, B, C, D; Class
II Division 1 and 2, Groups G and Coal Dust; Class III. Intrinsically
safe when connected as shown in Appendix 3.

Australian requirements (TestSafe)

TestSafe approved for Ex ia IIC T5 IP65 (Zone 0).

Installation ________________________________________________________________________

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CHAPTER 3

INSTALLATION

General instructions

NOTE

Mounting the probe cable in gas
group IIC spaces

The following instructions shall be followed to fulfil the specifications
of the EN 50284 for non conductive layer of the probe cable:

• Never mount or handle the probe cable when hazardous gases are

present !

• For achieving a conductive shield, cover the probe cable with

conductive material like metal or conductive tape or mount the
probe cable in a metal conduit !

• Assure that the conductive shield fulfils requirements of the

standard EN50284 (resistance less than 1 GΩ) and make sure that
it can not come loose in any operation situation !

NOTE

During the installation work of the sensor heads in gas group IIC
areas (requiring category I devices), it has to be guaranteed that
even in fault cases sparks generated by impacts or friction on the
housing's surface can never occur.

Selecting a place for the transmitter

Select a place with stable conditions for mounting the transmitter. Do
not expose the transmitter to direct sunlight or rain. A rain shield for
HMT360 transmitter is available. When mounting the sensor head,
select a place representing the process conditions.

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Temperature differences

If there is a difference between the process and ambient temperatures,
it is recommended to mount the sensor head and at least one meter of
cable inside the process. This is to avoid incorrect relative humidity
readings due to temperature difference. If this installation is not
possible and the sensor head must be installed through the wall (e.g.
with a flange), the sensor head and the cable must be insulated
carefully.

Checking the temperature reading

The actual temperature of the process can be measured with a
reference instrument to be compared with the transmitter reading. The
heat transfer is less evident if you remove the protective filter of the
sensor for a short-term test. However, never use the sensor long
periods without the filter as this may cause a faster contamination of
the sensor. The transmitter fulfils the specified EMC regulations with
the protective filter on the sensor head.

Installation ________________________________________________________________________

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Mounting the transmitter

FIGURE 3-1 Mounting the transmitter and detaching the probe

FIGURE 3-2 Different parts of the transmitter

1. Attach the mounting
plate to the wall with 4
screws.

2. Press down the
transmitter so that it
slides along the rails of
the mounting plate.

3. Fasten the transmitter
to the mounting plate
with the Allen screw.*

4. The probe can be
detached and replaced
when needed by simply
unfastening the two
Allen screws.

* 3 mm Allen key
provided

1. electronics unit

2. transmitter base

3. probe; including a part o

f

measurement electronics
(e.g. calibration memory
and the sensor head)

4. protective covers

5. flat cable

6. sensor head

7. cable glands

8. grounding terminals

9. RS232 connector

8

7

9

Installation_________________________________________________________________________

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Mounting the probes

NOTE

- Do not unsolder and then again resolder the sensor head cable

from and to the printed board during installation.

- Do not shorten or lengthen the probe cable

These procedures may alter the humidity calibration of the
transmitter.

The HMP362 - small pressure-tight
probe

The HMP362 probe is a small pressure-tight probe equipped with
installation flange. It is suitable for dewpoint measurements in natural
gas. When sampling in pressurized processes, the sampling cell
HMP302SC is available as an optional accessory.

HMP362 installation (without the sampling cell)

or chamber

3.2

m

i

n

.

ø

6

0

.

3

3

(

2

"

)

m

i

n

.

2

-

3

m

m

0

.

1

"

)

Screws, hexagon socked head (provided)

HMP362 Probe

Process pipe

Threaded sleeve

(not provided)

Threaded sleeve

O-Ring (provided)

ø

2

4

.

5

M6

9.5 (3/8")

(

3

1

/

3

2

"

)

Installation ________________________________________________________________________

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CAUTION

In pressurized processed it is essential to tighten the supporting nuts
and screws very carefully to prevent loosening of the probe by the
action of pressure.

NOTE

If the HMP362 is installed in a process with a pressure differing
from normal atmospheric pressure, please enter the pressure value
of the process (in hPa or mbar) into the transmitter memory via
the serial line (see page 42) or via the display/keypad (see page

33) .

The HMP363 probe for confined
spaces

The HMP363 is a small size general-purpose probe suitable for
installation in ducts and channels with the installation kit available.
The installation kit includes a flange, a supporting bar for the sensor
head cable and screws for attaching the flange to the duct wall. The
distance between the sensor and the channel wall can be adjusted. The
adjustment range is 100 - 320 mm, measured from the tip of the
sensor head to the flange.

HMP302SC (optional sampling cell)

Probe

Gas in

Gas out

Probe

Sampling cell

Clamp ( not needed
if sampling cell is
suspended on the
piping)

Installation_________________________________________________________________________

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FIGURE 3-3 Installation of the sensor head HMP363 in a channel

with a flange and a supporting bar

The HMP365 probe for high
temperatures

When installing the HMP365 sensor head in a duct or channel, there
should not be remarkable difference between temperatures inside and
outside of the duct. This can cause incorrect humidity readings.

FIGURE 3-4 Mounting the HMP365 sensor head in a duct or

channel.

HMP364 for pressurized spaces

The HMP364 pressure tight probe is designed for the humidity
measurements in pressurized rooms and industrial processes. This
probe is also available for dewpoint measurements in natural gas. The
probe is provided with a nut, a fitting screw and a sealing washer to
make the installation easier.

1. duct wall

2. plugged hole for
reference measurements
is recommended

3. flange

4. seal

5. supporting bar

6. sensor head

1. a plugged
hole for
reference
measurements

2. sensor head

3. mounting
flange

Installation ________________________________________________________________________

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CAUTION

In pressurized processed it is essential to tighten the
supporting nuts and screws very carefully to prevent
loosening of the probe by the action of pressure.

1. Unscrew the fitting screw from the nut and the sensor head.

2. Fasten the fitting screw to the chamber wall with a sealing washer.

Tighten the fitting screw into the threaded sleeve with a torque
spanner. The tightening torque is 150±10 Nm (110±7 ft-lbs)

3. Insert the body of the sensor head into the fitting screw and screw

the nut manually to the fitting screw until the connection feels tight.

4. Mark both the fitting screw and the nut hex.

5. Tighten the nut a further 30° (1/12 turn) or if you have a torque

spanner tighten it with a torque of 80 ±10 Nm (60±7 ft-lbs).

NOTE

After detachment the nut must be tightened
without increased effort.

6. Clean and grease the tightening cone of the fitting screw after every

tenth detachment. Change the sealing washer every time the fitting
screw is detached. Use high-vacuum grease (e.g. Down Corning,
Europe) or a similar grease.

1. tightening cone

2. nut

3. fitting screw

4. sealing washer

5. sensor head

;

∅ 13.5 mm

1. fitting screw

2. sealing washer

3. tightening cone

4. clean cotton stick

Installation_________________________________________________________________________

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NOTE

If the HMP364 is installed in a process with a pressure differing
from normal atmospheric pressure, please enter the pressure value of
the process (in hPa or mbar) into the transmitter memory via the
serial line (see page 42) or via the display/keypad (see page 33) .

Installation ________________________________________________________________________

Vaisala _________________________________________________________________________ 19

The HMP368 probe for measuring
humidity in pressurized pipelines
or moisture in liquids

The HMP368 probe is available with two lengths, standard 178 mm
and optional 400 mm. The probe is provided with a sliding fit which
enables different installation depths and makes the installation and
removal easier in pressurized processes. The probe is specially
designed for the measurements in pipelines. This probe is also
available for dewpoint measurements in natural gas.

When the probe is used in a pressurized pipeline or in liquids (e.g.
feeder routes) the sensor head should preferably be installed directly
in the process through a ball valve assembly, see page 20.

CAUTION

In pressurized processed it is essential to tighten the supporting nuts
and screws very carefully to prevent loosening of the probe by the
action of pressure.

NOTE

• When the HMP368 is installed in a process with a pressure

differing from normal atmospheric pressure, please enter the
pressure value of the process (in hPa or mbar) into the
transmitter memory via the serial line (see page 42) or via the
display/keypad (see page 33).

• Make sure that the temperature at the measurement point is equal

to that of the process, otherwise the humidity reading may be
incorrect.

Installation_________________________________________________________________________

Vaisala _________________________________________________________________________ 20

FIGURE 3-5 Probe dimensions: standard 178 mm and optional

400 mm

CAUTION

Take care not to damage the probe body. A damaged body makes the
probe head less tight and may prevent it from going through the clasp
nut.

Tightening the clasp nut

1. Adjust the probe to a suitable depth according to the type of

installation.

2. Tighten the clasp nut first manually.

3. Mark the fitting screw and the clasp nut.

4. Tighten the nut a further 50 - 60° (ca.1/6" turn) with a fork spanner.

If you have a suitable torque spanner, tighten the nut to 45±5 Nm
(33±4 ft-lbs).

1. clasp nut, 24 mm hex nut

2. fitting screw, 27 mm hex head

A: probe 178 mm:
adjustment range 120 mm;
A: probe 400 mm:
adjustment range 340 mm

Installation ________________________________________________________________________

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FIGURE 3-6 Tightening the clasp nut.

NOTE

Take care not to tighten the clasp nut more than 60° to avoid
difficulties when opening it.

Installing the probe through the
ball valve assembly

The best way for installing the sensor head to pressurized process or
pipeline is to install it through the ball valve assembly. This
installation makes it unnecessary to empty or shut down the process
for installing or removing the sensor head. Use the Vaisala
DMP248BVS ball valve set or a 1/2" ball valve assembly with a ball
hole of ∅14 mm or more. If you install the sensor head (∅ 13.5 mm)
in a process pipe, please note that the nominal size of the pipe must be
at least 1 inch (2.54 cm). The manual press tool can be used to press
the sensor head into the pressurized (< 10 bar) process or pipeline.

1. probe

2. clasp nut

3. pen

4. fitting screw

Installation_________________________________________________________________________

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FIGURE 3-7 Installing the sensor head through the

DMP248BVS ball valve assembly.

Install the sensor head transversely against the direction of the process
flow.

NOTE

Installation or removing the probe through a ball valve assembly is
possible without shutting the process when the pressure is less than 10 bar.
With 10...40 bar pressures you must shut down the process before
installing or removing the probe. The maximum operation pressure for the
probe HMP368 is 40 bar.

1. sensor head

2. handle of the ball
valve

3. ball of the ball valve

4. process chamber /
pipeline

5. manual press tool

6. the groove on the
probe indicates the
upper adjustment limit

7. filter

1

2

3

4

5

6

7

Electrical connections________________________________________________________________

Vaisala _________________________________________________________________________ 23

CHAPTER 4

ELECTRICAL CONNECTIONS

Refer to local requirements regarding cabling, grounding and galvanic
isolator or barrier connections.

WARNING

Be sure that the main power switch of the transmitter is set off before
making any electrical installations in hazardous areas.

1. Open the transmitter cover and remove the protective cover of

the transmitter base.

2. Thread the power supply wires through the cable gland (Figure

3-2, item 7)

3. Connect the unpowered power supply wires to the connectors:

CH1 (humidity) and CH2 (temperature). Both channels require
an own power supply. NOTE! As CH1 is a main output, the
transmitter does not operate if only CH2 is connected (CH2 is
optoisolated from transmitter electronics).

4. Replace the protective cover. Turn the transmitter on ON with

the ON/OFF switch (Figure 9-1, item 2).

5. Close the cover. The transmitter is ready for use.

When using the transmitter in hazardous places, the use of
galvanic isolators or barriers is essential. The following barrier &
isolator are available in Vaisala: barrier No. 210664 (STAHL
9001/51-280-091-141) for USA&Canada and galvanic isolator
No. 212483 (STAHL 9160/13-11-11) or barrier No. 210664 for
EU. Examples of connections are presented on page 25.

Electrical connections ________________________________________________________________

Vaisala _________________________________________________________________________ 24

Installation in hazardous locations

US and Canadian requirements

USA (FM): Wiring for intrinsically safe operation is shown in APPENDIX 2.
Canada (CSA): Wiring for intrinsically safe operation is shown in APPENDIX 3.

European requirements

CATEGORY 1 (zone 0)

The HMT360 has to be connected to Exia-certified associated apparatus with galvanic
isolation, gas group IIB or IIC. NOTE! If both analog outputs are in use, the channel 1 (-) and
channel 2 (-) must be short circuited (see figure 4-3).

CATEGORY 2 or 3 (zone 1 or 2)

The HMT360 has to be connected either to a zener barrier or galvanic isolator NOTE! If both
analog outputs are in use with a galvanic isolator, the channel 1 (-) and channel 2 (-) must be
short circuited (see figure 4-3).

Figures 4-1 and 4-2 present examples of galvanic isolators and zener barrier connections (only
CH1 connected).

Maximum load calculation for the barrier

Always check the technical data of galvanic isolator or zener barrier to define maximum load.
If the maximum load is not included in specifications it can be determined as follows.

Example: Stahl 9002/13-280-093-00 (zener barrier)

General specifications of the HMT360
Supply voltage Uin = 24 V (12...35 V)
Maximum current I

max

= 20 mA (100%RH)

Minimum operating voltage for HMT360 U

min

= 12 V (15 V with serial port )

Cable resistance (as an example) R

cable

= 0.085 ohm/m/core (2*0.085 ohm/m/pair)

Cable lenght =250 m

R

Ctot

= 2*0.085 ohm/m*250m= 45 ohm

Stahl 9002/13-280-093-00 (values taken from the specifications):
Typical end to end resistance R

barrier

= 340 ohm

Max. additional voltage drop (20mA) U

add

= 1 VDC

Voltage drop U

drop

= I

max

*(R

Ctot

+ R

barrier

) + U

add

= 20 mA*(45+340)ohm + 1 V = 8.7 V

Voltage for R

l

U

Rl

= U

in

- U

min

- U

drop

= 24 V - 12 V - 8.7 V = 3.3 V

Maximum load R

lmax

= URl/I

max

= 3.3 V / 20 mA = 165ohm , R

lmax

< 165ohm

Electrical connections________________________________________________________________

Vaisala _________________________________________________________________________ 25

HMT360 connected to a galvanic isolator

a) current signal controller

b) voltage signal controller

FIGURE 4-1. HMT360 connected to a galvanic isolator.

C H 1

+ +-

-

C H 2

Rl

U

Power Supply

Galvanic
Separator

Controller

U = I*Rl

L+
L-

C H 1

+

+

--

C H 2

I

Power Supply

Galvanic
Separator

Controller

L+
L-

I = 4...20mA

HAZARDOUS AREA SAFE AREA

HAZARDOUS AREA SAFE AREA

Electrical connections ________________________________________________________________

Vaisala _________________________________________________________________________ 26

HMT360 connected to a zener barrier

a) current signal controller

b) voltage signal controller

FIGURE 4-2 HMT360 connected to a zener barrier.

C H 1

+

+-

-

C H 2

Power Su pply

Zener
Barrier

I = 4...20mA

I

Controller

C H 1

+

+

-

Rl

U

Power Supply

Zener
Barrier

Controller

U = R x I

+

-

-

C H 2

HAZARDOUS AREA SAFE AREA

HAZARDOUS AREA

SAFE AREA

Electrical connections________________________________________________________________

Vaisala _________________________________________________________________________ 27

Examples of connections

FIGURE 4-3 STAHL 9160/13-11-11 (galvanic isolator).

FIGURE 4-4 STAHL 9001/51-280-091-141 (zener barrier).

Make the connection
between the

- terminals always
when using a
galvanic isolator !

STAHL 9160/13-11-11

-Ch2+

HMT360 Connection

HAZARDOUS AREA

-Ch1+

board

SAFE AREA

Load Ch1

Load Ch2

V+

V-

18...31,2VDC

V-

V+

18...31,2VDC

12

10

10

12

7
9
1
2

9

2

1

7

(+)

(-)

(-)

(+)

HAZARDOUS AREA SAFE AREA

HMT360 Connection
board

-Ch1+ -Ch2+

Load Ch2

20...35 VDC

20...35 VDC

Load Ch1

STAHL 9001/51-280-091-141

1

2

2

1

4

3

3

4

Electrical connections ________________________________________________________________

Vaisala _________________________________________________________________________ 28

FIGURE 4-5 MTL5044 (galvanic isolator).

Grounding

When grounding the transmitter, follow the local requirements. Use at least 4 mm

2

grounding cable when grounding the transmitter or barrier. Note that the allowed
resistance between barrier and system ground must be less than 1 ohm. See the figure
below.

FIGURE 4-6 Grounding.

HAZARDOUS AREA

-Ch2+-Ch1+

HMT360 Connection
board

5

4

1

2

9

12

11

SAFE AREA

Load Ch1

Load Ch2

20...35VDC

Vs+

Vs-

-

+

-

+

+

-

+

-

14

13

MTL5044

Zener
Barrier

Instrument
system

Barrier ground

System groun

d

-Ch1+

-Ch2+

HAZARDOUS AREA SAFE AREA

Operation _________________________________________________________________________

Vaisala _________________________________________________________________________ 29

CHAPTER 5

OPERATION

Turn the transmitter on ON with the ON/OFF switch (Figure 9-1, item

2).

HMT360 with display

Measurement readings appear on the display after switching power
ON. The analog output signals can be read from the system or load
resistor.

HMT360 for Natural Gas

When switching on the HMT360 for natural gas, the existing pressure
setting appears on the display; the default setting is 1000 hPa (=1 bar
or 14.5 psi).

To modify the pressure setting, turn the transmitter's internal

CALIBRATION ENABLED/DISABLED dip switch to position ENABLED

(up). Adjust the pressure reading with buttons ▲ and ▼ on the
display cover; the adjustment step is 100 hPa). Acknowledge the value
with button E. To complete the pressure setting, turn the dip switch
back to position DISABLED (down). If the pressure setting is not
modified, the measurement readings appear automatically on the
display after 60 seconds.

NOTE

Avoid static discharge! Always use a wet cloth for wiping the
display.

HMT360 without display

If the transmitter does not have a display, the red LED indicator on the
cover indicates various phases of calibration and possible errors. In
normal operation it is not lit. If the LED is lit and all calibration or test
dip switches are disabled, it is an indication of an internal error.

Operation _________________________________________________________________________

Vaisala _________________________________________________________________________ 30

Otherwise, the LED indicates the following:

LED blinking = calibration of the dry end (offset)

LED lit = calibration of the wet end (gain)

NOTE

If calibration is concluded but dip switch settings are not restored, the
LED indicator keeps blinking.

Dip switch functions

The table below is also printed on the protection
board:

n o p q r s t u

n: ANALOG OUTPUT TEST ON/OFF:

if you turn the switch to ON position (up), you can force the outputs to
states 4 mA, 12 mA and 20 mA by pressing the buttons ▲ and ▼on
the cover.

o: CALIBRATION DISABLED/ENABLED:

the EEPROMs are write protected. If this switch is in the DISABLED
position (down), it does not allow any calibrations or scalings.

NOTE

Keep this switch always in the disabled position during normal use of
the transmitter!

Operation _________________________________________________________________________

Vaisala _________________________________________________________________________ 31

p and q CALIBRATION RH, T, ANALOG:

with these combinations you can perform relative humidity,
temperature or analog output calibrations with a multimeter or with
the transmitter display unit. Turn the dip switches to the desired
position according to the table printed on the protective cover.

r OUTPUT QUANTITIES:

determines whether the output units are metric (down) on non-metric.

s, t and u SELECT OUTPUT QUANTITIES:

with the three dip switches on the right, you can select the output
quantities according to the table printed on the right side of the
protective cover. Note that only the ordered quantities can be selected.
The SPECIAL option gives you the choice of setting any ordered
quantity to each channel.

NOTE

Always restore the dip switch settings after having tested the analog
outputs or performed the calibration.

Operation errors ____________________________________________________________________

Vaisala _________________________________________________________________________ 32

CHAPTER 6

OPERATION ERRORS

The following indicates an operation error of the
HMT360:

• Analog output(s) current drops below 4 mA

• Display shows ERROR

• LED on the cover is lit and no calibration is going on (transmitters

without a display)

In the case of error:

• Check that the sensor is connected properly

• Check if there is condensed water in the probe, if yes, let the probe dry

Cleaning the sensor from glycol in a natural
gas application

If a glycol layer on the VAISALA HUMICAP® sensor is disturbing
the moisture measurement, the sensor can be cleaned on site soaking
the sensor to de-ionized water or to IPA (isopropanol, propan-2-ol).

Operation errors ____________________________________________________________________

Vaisala _________________________________________________________________________ 33

1. Remove the sintered filter carefully.

2. Dip the sensor in de-ionized water or IPA (max 1 minute).

3. Gently blow the sensor dry with dry gas (Nitrogen) if available.

4. When the sensor and probe are dry, set the filter back on the

probe.

NOTE

Do not touch the sensor surface, especially if removing the
HUMICAP® sensor from the probe.

Only dipping to de-ionized water or IPA is allowed, other agents like
ethanol cannot be used.

Do not keep the sensor for more than one minute in the water or IPA.

The water or IPA temperature must be below 30 °C (86 °F).

Do not use a cotton stick or any other mechanical means for cleaning
and/or drying the sensor.

In case of constant error, please contact Vaisala Service (see Chapter
2: Maintenance).

Display/keypad commands____________________________________________________________

Vaisala _________________________________________________________________________ 34

CHAPTER 7

DISPLAY/KEYPAD COMMANDS

With these commands you can scale the outputs and select special
output quantities if the transmitter configuration allows that.

NOTE

Chapter 9 describes separately display/keypad commands for the
calibration.

Setting the pressure for calculations

In humidity transmitters, ambient pressure is used for the mixing ratio
and wet bulb calculations. In dewpoint transmitters (natural gas
applications), the process pressure in the measurement point is
required to achieve the specified accuracy.

To modify the pressure settings, turn the transmitter's internal

CALIBRATION ENABLED/DISABLED dip switch to position ENABLED

(up). Press button C on the display cover: text "SCAL" appears on the
display. Then press button E until the following display appears (the
numeric value is always the existing setting, in this example 1013.25):

Adjust the pressure reading with buttons ▲ and ▼. Acknowledge the
value with button E. To complete the pressure setting, turn the dip
switch back to position DISABLED (down).

See the pressure conversion table on page 42.

Display/keypad commands ___________________________________________________________

Vaisala _________________________________________________________________________ 35

Selecting the output quantities

HMT360 for Natural Gas

Two quantities are shown on the LCD. The upper half of the display
shows the moisture, whereas the lower half is reserved for the
temperature reading.

Upper half of the display

To modify the displayed quantity, turn the transmitter's CALIBRATION

ENABLED

/DISABLED dip switch to position ENABLED (up). Select the
required quantity with button ▲ on the display cover, and
acknowledge the value with button E. To complete the selections, turn
the dip switch back to position DISABLED (down).

When the OUTPUT QUANTITIES METRIC/NON METRIC dip switch is in the

METRIC (down) position, the available quantities are dew/frost point

temperature (Td °C), parts per million (ppm), and absolute humidity in
mg/m3 (W). When the dip switch is in the NON METRIC (up) position,
the available quantities are dew/frost point temperature
(Td °F), parts per million (ppm), and absolute humidity in lb/mmscf
(W).

Lower half of the display

The OUTPUT QUANTITIES METRIC/NON METRIC dip switch can be used
to select between °C and °F.

It is possible to check the pressure setting of the transmitter by
pressing button ▼. To return to the temperature reading, press button
▼ again.

Selecting the analog outputs

You can select the output quantities for channels 1 and 2 by turning
the transmitter's CALIBRATION ENABLED/DISABLED dip switch to
position ENABLED (up) and the three OUTPUT SELECTION dip switches
to position

SPECIAL (all up).

Display/keypad commands____________________________________________________________

Vaisala _________________________________________________________________________ 36

Press button C on the display cover: text "SCAL" appears on the
display. Then press button E until the following display appears:

The characters on the second line of the display in this menu
correspond to the quantities according to the following table:

Table 2 Available Quantities

character quantity abbreviation availability

0 relative humidity RH A, D
1 temperature T A, D, F, H, N
2 dewpoint temperature Td D, N
3 absolute humidity a D
4 mixing ratio x D
5 wet bulb temperature Tw D
6

volume concentration

ppm H, N
7 water activity aw H, F
8 relative humidity of saturation RS H
9 saturation temperatur Ts H
A water content w N

A: available for HMT360A
D: available for HMT360D
F: available for HMT360F
H: available for HMT360H
N: available for HMT360N

Select the quantity for channel 1 with buttons ▲ and ▼ and
acknowledge the selection with button E.

If the transmitter is equpped with two analog channels, select the
quantity for channel 2 in the same way, for example:

Press button C to exit the display command mode or continue by
setting the pressure.

NOTE

Remember to restore the dip switch settings.

Display/keypad commands ___________________________________________________________

Vaisala _________________________________________________________________________ 37

Scaling the analog outputs

Turn the transmitter's internal dip switch CALIBRATION ENABLED/

DISABLED to upward position (ON). Press button C on the display

cover and a text similar to the following appears:

Numbers on the second line indicate the low end scaling of channel 1
currently stored in the transmitter memory. The text SET LO on the
lower left corner indicates that you can now change the low end
scaling with buttons ▲ and ▼. Acknowledge the value with button E
and a text similar to the following appears:

Numbers on the second line indicate the high end scaling of channel 1.
The text SET HI on the lower left-hand corner indicates that you can
now change the high end scaling with buttons ▲ and ▼.
Acknowledge with button E.

If there is another channel available, the display shifts to the scaling
menu of channel 2. You can now scale the analog outputs for the
channel 2 in the same way as described above.

Press button C to exit the display command mode or continue by
selecting the output quantities. This menu starts automatically after the
scaling menu only if the

OUTPUT SELECTION dip switches are on the

position SPECIAL (all up) from the beginning.

NOTE

Remember to restore the dip switch settings.

LO

Serial interface _____________________________________________________________________

Vaisala _________________________________________________________________________ 38

CHAPTER 8

SERIAL INTERFACE

WARNING

The serial interface MUST NOT be used in hazardous areas.

Use the serial interface for calibration and testing purposes in safe
areas only. Always use the serial interface cable (optional accessory,
order code: 25905ZZ). Connect one end of the cable to the serial port
of your computer and the other to the connector marked 'RS 232C' on
the transmitter's electronics unit (see Figure 3-2, item 9).

NOTE

With serial communication the current consumption increases
approximately to 7 mA and the transmitter is not able to operate with
4 mA. Therefore, it is recommended to use serial communication
only temporarily for changing settings or for calibrating the
transmitter in a safe area. With serial port, the minimum supply
voltage is 15 VDC.

NOTE

The transmitter incorporates a serial interface detector. However, not
all terminals or PC serial ports (e.g. opto-isolated or ports not
meeting RS232C standards) recognize this standard. If the
communication is not possible via a serial interface, use a forced
activation by pressing simultaneously buttons ▲ and E on the
transmitter cover. To deactivate the forced activation, press these
buttons again or reset the transmitter. If the transmitter does not
receive any commands for half an hour, it automatically closes the
serial communication.

Serial communication settings

TABLE 8-1 Serial communication settings

parameter value

bauds 2400
parity none
data bits 8
stop bits 1

Serial interface _____________________________________________________________________

Vaisala _________________________________________________________________________ 39

To start giving commands, make sure that the HMT360 is connected
to a serial port of your computer and that the terminal session is open.
Give commands by typing them on your computer according to the
following instructions. In these commands, ↵ stands for pressing

ENTER.

NOTE

Each time the HMT360 transmitter sends something to the terminal,
it also sends line feed and carriage return.

Selecting the analog outputs

Turn the internal dip switch CALIBRATION ENABLED/DISABLED to
ON-position before the selecting the analog outputs and return it to
OFF- position after selecting .

ASEL xxx yyy ↵

where: xxx = quantity of channel 1 and yyy = quantity of channel 2

output quantity abbreviation

relative humidity RH
temperature T
dewpoint temperature Td
absolute humidity a
mixing ratio x
wet bulb temperature

1

Tw

mass proportion

1

ppm

water activity

1

aw
relative humidity of saturation1RS
saturation temperature

1

Ts
water content

2

w

1

Available only for HMT368H for moisture measurements in liquid.

2

Available only for HMT360N for natural gas

Example:
>asel rh t ↵

Ch1 RH lo : 0.00 %RH
Ch1 RH hi : 100.00 %RH
Ch2 T lo : -40.00 'C
Ch2 T hi : 60.00 'C
>

Serial interface _____________________________________________________________________

Vaisala _________________________________________________________________________ 40

Scaling the analog outputs

Turn the internal dip switch CALIBRATION ENABLED/DISABLED to
ON-position before the scaling the analog outputs and return it to
OFF- position after scaling.

Szz aa.a bb.b ↵

where: zz = quantity (RH, T, Td, x, a, Tw, ppm, aw, RS, Ts)

aa.a = lower limit of the quantity
bb.b = upper limit of the quantity

Example: Scaling the relative humidity:

>SRH 0 100 ↵
RH lo 0.00 %RH
RH hi 100.00 %RH
>

Exception: When you have natural gas transmitter and you scale the
quantity of water content w (mg/kg or lb/mscf) give a command

SNG1.

Adjustment commands

Turn the internal dip switch CALIBRATION ENABLED/DISABLED to
ON-position before the calibration and return it to OFF- position after
calibration.

Note that HMT360 for natural gas can be checked but not adjusted
by a user.

Relative humidity adjustment

NOTE

Read also the calibrator e.g. HMK15 manual and refer to page 47 of
this manual for more detailed instructions on salt bath calibration.

CRH ↵

Serial interface _____________________________________________________________________

Vaisala _________________________________________________________________________ 41

The transmitter asks and measures relative humidity and calculates the
calibration coefficients, for example:

>CRH ↵
RH : 1.82 1. ref ? 0 ↵
Press any key when ready... ↵
RH : 74.22 2. ref ? 75 ↵

OK
>

The OK indicates that the calibration has succeeded.

Temperature adjustment

CT ↵

The transmitter asks and measures temperature readings and calculates
the calibration coefficients, for example:

>CT ↵
T : 0.81 1. ref ? 0.5 ↵
Press any key when ready... ↵
T : 99.12 2. ref ? 99.5 ↵

OK
>

The OK indicates that the calibration has succeeded. When performing
one-point calibration press only ↵ for 2. reference.

Analog output calibration

Connect the HMT360 to a multimeter. Give the following command.

ACAL ↵

1. Disconnect the serial cable from the transmitter while reading the

multimeter value for the CH1 (I1).

2. Reconnect the serial cable. Type the multimeter reading and press

↵.

3. Type the higher current multimeter reading and press ↵.

>ACAL ↵
Ch1 I1 (mA) ? 4.846 ↵
Ch1 I2 (mA) ? 19.987 ↵

>

Serial interface _____________________________________________________________________

Vaisala _________________________________________________________________________ 42

Output commands

Testing the analog outputs

This command outputs the current value of each channel and the
corresponding control signal of the digital-to-analog converter.

ITEST aa.aaa bb.bbb ↵

where: aa.aaa = current value to be set for channel 1 (mA)

bb.bbb = current value to be set for channel 2 (mA)

For example:

>ITEST 8 12 ↵

8.000 3F8 12.000 70O
>

>ITEST ↵

6.349 25A 19.001 E93
>

The set current values remain valid until you give the command
ITEST without readings. With this command the desired outputs of
the transmitter are shown.

Note! When outputting low currents from channel 1, remember to
remove RS232C-cable while reading the current output, because of
the increased current consumption for using RS port.

Outputting the measurement
values

SEND ↵

This command outputs the measured values in one point.

Activating a continuous output

R ↵

With the command R the transmitter outputs measured values
continuously.

Serial interface _____________________________________________________________________

Vaisala _________________________________________________________________________ 43

Stopping the continuous output

S ↵

The continuous outputting is stopped with the command S. If
outputting is active, this command is not echoed.

Setting the output interval

INTV n xxx ↵

where: n = 1 - 255 xxx = S, MIN or H

Sets the output interval when the transmitter outputs measurement
readings. The time interval is used when the continuous output is
active. For example, the output interval is set to 10 minutes:

>INTV 10 min ↵
Output intrv. : 10 min
>

Setting the ambient pressure for calculations

Turn the internal dip switch CALIBRATION ENABLED/DISABLED to
ON-position before setting the pressure and return it to OFF- position
after setting.

PRES aaaa.a ↵

where: aaaa.a = pressure (hPa)

>PRES 2400 ↵

Pressure : 2400
>

Pressure conversion chart

mmHg/Torr inHg atm bar psi

hPa/mbar

1 1.333224 33.86388 1013.25 1000 68.94757

mmHg/Torr

0.7500617 1 25.40000 760 750.0617 51.71493

inHg

0.02952999 0.03937008 1 29.921 29.52999 2.036021

atm

0.00098692 0.00131597 0.033422 1 0.98692 0.068046

bar

0.001 0.001333224 0.03386388 1.01325 1 0.06894757

psi

0.01450377 0.01933678 0.4911541 14.6962 14.50377 1

Example: 29.9213 inHg = 29.9213 x 33.86388 = 1013.25 hPa / mbar

NOTE

Conversions from mmHg and inHg are defined at 0 °C and for
mmH2O and inH2O at 4 °C.

FROM

TO

Measuring at overpressure ____________________________________________________________

Vaisala _________________________________________________________________________ 44

CHAPTER 9

MEASURING AT OVERPRESSURE

The probes HMP362, HMP364 and HMP368 are designed for
humidity measurement at overpressure. The maximum measurement
pressures depend on the probe as follows:

HMP362: 0...167 bar (16,7 MPa), for natural gas, sample cell

HMP302SC available

HMP364: 0...100 bar (10 MPa), for pressurized rooms and processes,

probe is provided with a nut, fitting screw and sealing
washer

HMP368: 0...40 bar (4 MPa), for pressurized pipelines, ball valve set

available

The accuracy of the dewpoint measurement is affected by pressure in
the measurement chamber. The actual pressure in the sampling cell
shall be set to the transmitter by using the serial line command PRES
(Setting the ambient pressure for calculations), page 42 or by using
the keypad commands, page 33.

CAUTION

In pressurized processed it is essential to tighten the
supporting nuts and screws very carefully to prevent
loosening of the probe by the action of pressure.

Pressure regulator recommended

When sampling pressurized processes exceeding the maximum
measurement pressure of the probe, the pressure in the measurement
chamber must be regulated to acceptable level or below. It is
recommended to use pressure regulator before the measurement
chamber to prevent remarkable pressure variations.

Calibration and adjustment____________________________________________________________

Vaisala _________________________________________________________________________ 45

CHAPTER 10

CALIBRATION AND ADJUSTMENT

Calibration interval

HMT360 is calibrated as shipped from the factory. Typical humidity calibration
interval is one year. Depending on the application it may be good to make the first
calibration check earlier.

Factory calibration and adjustment

The device (or only the electronics unit) can be sent to Vaisala Service Centers for
calibration and adjustment, see contact information on page 9. HMT360 for

natural gas shall be adjusted always in Vaisala Service Center.

Calibration and adjustment by the user

Note that HMT360 for natural gas can be checked but not adjusted by a user.

Calibration is carried out by using the keypad or by using serial commands. The
following additional equipment is needed in calibration of the HMT360:

• power supply for the channel(s) to be calibrated (12-24 VDC)

• a multimeter for the HMT360 without a display

• the calibrated references

Firstly, the electronics unit is removed from the transmitter base to perform a
calibration in safe area. Secondly, the power supply and a multimeter is connected
to the electronics unit according to the following instructions.

Calibration and adjustment ____________________________________________________________

Vaisala _________________________________________________________________________ 46

Removing the electronics unit for the calibration

Connections

Connections

FIGURE 9-2 Connecting the power supply and multimeter for calibration.

1. Unfasten the screws and
open the cover.

2. Switch the transmitter off
with the ON/OFF switch.

3. Disconnect the flat cable
by lifting it carefully e.g. with
a screw-driver.

4. Turn the electronics unit
slightly upwards to release it
from the hinges. Leave the
transmitter base with the
cable connections on place.
When putting the electronics
unit back to place, attach the
upper hinge first.

FIGURE 9-1 Detaching the electronics

unit with the probe for calibration.

Calibration and adjustment____________________________________________________________

Vaisala _________________________________________________________________________ 47

1. Connect with banana plugs a power supply (12...24 VDC, with a serial port the

minimum supply voltage is 15 VDC ) to the terminals B1(-) and C1(+) (channel 1), see
Figure 9-2.

2. Connect the multimeter in series with the supply, B1(-) and A1(+).

3. Follow the same procedure with channel 2 using the terminals B2 (-) and C2 (+). When

calibrating both channels at the same time, use two galvanically separated power
supplies.

You can now calibrate or check the humidity and temperature or the analog outputs
according to the instructions given in calibration chapters.

If the current measurement is needed in a hazardous area, the multimeter is connected to the
terminals A1/A2 (+) and B1/B2 (-). Use only an approved multimeter.

WARNING

The power supply connectors (C1 and C2) MUST NOT be used in hazardous
areas. For calibration in a hazardous area use only an approved multimeter,
which fulfils the safety factors printed on the protective cover.

Calculating the correspondence of current
values and output quantities

When using HMT360 without a display, calibration is carried out by using a multimeter.
Use the following equations to calculate the current values corresponding the reference
output quantities.

min)max(

min)(

164

QQ

QQref

mAmAI

−

−

⋅+= (9-1)

where: Qref = reference value of the calibrated quantity

Qmin = value corresponding to 4 mA
Qmax = value corresponding to 20 mA

Example 1:

relative humidity scaling 0 - 100 %RH, reference 11.3 %RH:

mA

RHRH

RHRH

mAmAI 808.5

)%0%100(

)%0%3.11(

164 =

−

−

⋅+=

Example 2:

temperature scaling -40 - +120 °C, reference 22.3 °C

mA

CC

CC

mAmAI 230.10

)40120(

)403.22(

164 =

°−−°

°−−°

⋅+=

Calibration and adjustment ____________________________________________________________

Vaisala _________________________________________________________________________ 48

Relative humidity calibration

Automatic two-point calibration
(only with HMT360 with display)

The automatic calibration procedure is a user friendly way to calibrate
with salt solutions; user do not have to feed the reference values to the
HMT360. The transmitter displays the accurate value based on the
measured temperature and the Greenspan table stored into the
transmitter memory. The display chart of the calibration procedure is
presented in FIGURE 9-3 Display chart of the automatic calibration
procedure.

− Set the calibration dip switch to ENABLED position and select RH

calibration by using switches 3 and 4 (see Chapter 5: Dip switch
functions).

− Remove the filter and insert the probe head into a measurement

hole of the LiCl salt chamber in the humidity calibrator.
Acknowledge by pressing the button E. Alternatively select the 0.1
(humidity in Nitrogen) with buttons ▲ and ▼. Acknowledge with
the button E.

− The transmitter remains to wait for the process stabilization (10-15

min) and then stores the correction.

− Insert the probe head into a measurement hole of the NaCl salt

chamber in the humidity calibrator. Acknowledge by pressing the
button E. Alternatively you can select K2SO4 value with buttons
▲ and ▼.

− The transmitter remains to wait for the stabilization and then stores

the correction. The text CAL PASS is displayed after the calibration
is performed.

NOTE

Remember to restore the dip switch settings.

Calibration and adjustment____________________________________________________________

Vaisala _________________________________________________________________________ 49

FIGURE 9-3 Display chart of the automatic calibration procedure.

Calibration enabled
RH calibration on

Restore switches

Calibration and adjustment ____________________________________________________________

Vaisala _________________________________________________________________________ 50

Manual calibration

Low end adjustment

- Remove the filter and insert the probe head into a measurement
hole of the dry end reference chamber (e.g. LiCl: 11 %RH) in the
humidity calibrator.

NOTE

If you use serial commands, please refer to page 39.

− Set the calibration dip switch 2 to ENABLED (up) position and

select RH calibration by using switches 3 and 4 (see Chapter 5: Dip
switch functions).

- Press button C to ignore the automatic calibration procedure. The
humidity reading measured by the transmitter appears on the
display and on the lower left corner you can see the text SET LO. If
the transmitter has no display, the LED indicator is blinking.

- According to the calibrator used, wait at least 10 - 15 minutes for
the sensor to stabilize; use a multimeter or the transmitter display to
monitor the stabilization.

- Press the buttons ▲ and ▼ to adjust the display reading or
multimeter reading to correspond the reference value (when using a
multimeter calculate the current value corresponding to the
reference humidity by using the equations presented in page 46).
Press the button E to conclude the low end adjustment.

- If the low end adjustment is sufficient, press the button E again to
conclude the calibration and restore the dip switch settings; set the
calibration dip switch to position DISABLED (down). To continue
with the high end adjustment follow the instructions in next
chapter.

High end adjustment (two-point calibration)

- After having made the low end adjustment, insert the probe head
into a measurement hole of the NaCl (75 %RH) salt chamber in the
humidity calibrator. Please, note that the difference between the
two humidity references must be at least 30%RH.

NOTE

If you use serial commands, please refer to page 39.

- The readings measured by the transmitter appear on the display, as
well as the text, SET HI on the lower left hand corner. If the
transmitter has no display, the LED indicator lights up.

Calibration and adjustment____________________________________________________________

Vaisala _________________________________________________________________________ 51

- Wait at least 10 - 15 minutes for the sensor to stabilize; use a
multimeter or the transmitter display to monitor the stabilization.

- Press the buttons ▲ and ▼ to adjust the display or multimeter
reading (when using a multimeter calculate the current value
corresponding to the reference humidity by using the equations
presented in page 47) and conclude the calibration with the button
E.

- Restore the dip switch settings. Set the calibration dip switch to
position DISABLED (down).

Temperature calibration in one point

Always use a high quality standard for calibrating the temperature.

NOTE

If you use serial commands, please refer to page 40.

- Set the calibration dip switch to position ENABLED (up).

- Set the calibration dip switches to position 'TEMPERATURE

CALIBRATION

' according to the table printed on the protective
cover. The temperature value measured by the transmitter appears
on the display as well as the text SET LO on the lower left corner. If
the transmitter has no display, the LED indicator starts to blink.

- Let the sensor stabilize; use a multimeter or the transmitter display
to monitor the stabilization.

- Press the buttons ▲ and ▼ to adjust the display or multimeter
reading to correspond the reference value (when using a multimeter
calculate the current value corresponding to the reference humidity
by using the equations presented in page 46). Conclude the one
point calibration by pressing the button E twice.

Specifications ______________________________________________________________________

Vaisala _________________________________________________________________________ 52

CHAPTER 11

SPECIFICATIONS

Performance

Relative humidity

Measurement range 0 - 100 %RH
Accuracy (including non-linearity and repeatability);
when calibrated against:
high quality, certified humidity
standards ±1 %RH (0 - 90 %RH)

±2 %RH (90 - 100 %RH)
salt solutions ±2 %RH (0 - 90 %RH)
(ASTM E104-85) ±3 %RH (90 - 100 %RH)

Response time (90%) at 20 °C in still air
(with sintered filter) 15 seconds
Sensors:
HUMICAP®180 for typical applications
HUMICAP®L for applications with a demanding

chemical environment (max. +40 °C

in high humidities)

Moisture in natural gas (HMT362N/364N/368N)

Dewpoint measurement

Measurement range -50...+50 °C (-58...+122 °F) T

d

Accuracy ±2 °C (±3.6 °F) (see the graph on

the next page)
Response time 63 % [90 %]

-20 -> +10 °C (-4 -> +50 °F) 6 s [32 s]
+10 -> -20 °C (+50 -> -4 °F) 120 s [370 s]
Sensor Vaisala HUMICAP® 180M

Specifications ______________________________________________________________________

Vaisala _________________________________________________________________________ 53

Calculated variables available (typical ranges)

Water content 0...20 lb/mmscf, 0...326 mg/m

3

Parts per million by volume 0...500 ppm

v

Water activity in jet fuel applications(HMT368H/J)

Measurement range 0...1 aw (@-40...+180 °C (-

40...+356 °F)

Accuracy
when calibrated against high-quality, certified humidity standards:

±0.01 (0...0.9)
±0.02 (0.9...1.0)

when calibrated against salt solutions (ASTM E104-85):

±0.02 (0...0.9)

±0.03 (0.9...1.0)
Response time (90 %) at +20 °C in
still oil (stainless steel filter) 10 min

Humidity sensor HUMICAP

®

Calculated variables available water content

relative humidity for saturation

saturation temperature
Accuracy of the water content better than ±15 % of the reading

Temperature

Measurement range -40...+180 °C

(depends on selected probe)
Typical accuracy of electronics
at +20 °C ±0.1 °C
Typical temperature dependence
of electronics 0.005 °C/°C
Sensor Pt 1000 RTD 1/3 Class B IEC 751

Specifications ______________________________________________________________________

Vaisala _________________________________________________________________________ 54

Calculated variables (typical ranges)

With HMP361 probe

dewpoint temperature -40...+60 °C
mixing ratio 0...160 g/kg d.a.
absolute humidity 0...160 g/m

3

wet bulb temperature 0...+60 °C

With HMP363, HMP364, HMP365 & HMP368

dewpoint temperature -40...+100 °C
mixing ratio 0...500 g/kg d.a
absolute humidity 0...600 g/m

3

wet bulb temperature 0...+100 °C

Outputs

Two analog outputs Two wire 4...20 mA
(one standard, one optional)
Typical accuracy of analog
Outputs at +20 °C ±0.05% full scale
Typical temperature dependence
of analog outputs 0.005% / °C full scale
RS232C serial output for service use connector type RJ45
only in safe area
Output connections via safety barriers

Classification with current outputs

EU (94/9/EC, ATEX100a) II 1 G EEx ia IIC T4

PTB 00 ATEX 2112 X

Safety factors: Ui=28 V, Ii=100 mA, Pi =0.7 W

Ci=1 nF, Li=0 H
Environmental
specifications: Tamb = -20...+60 °C

Pamb = 0.8...1.1 bar

Dust classification: II 1 D (IP65 T= 70 °C)
(with protection cover) VTT 04 ATEX 023X

U.S.A. (FM) Classes I, II, III

Division 1: Groups A-G

Division 2: Groups A-D, F and G

FM Project ID:3010615
Safety factors: Vmax=28VDC,Imax=100mA,Ci=1nF, Li=0,

Pi=0.7 W, T

amb

= 60 ºC, T5

Specifications ______________________________________________________________________

Vaisala _________________________________________________________________________ 55

Canada (CSA) Class 1, Divisions 1 and 2, Groups A,B,C,D

Class II, Divisions 1 and 2, Groups G and Coal
Dust
Class III
CSA File No: 213862 0 000;
CSA report 1300863
T

amb

= 60 ºC, T4

Japan (TIIS) Ex ia IIC T4

Code number: C15354

Safety factors Ui= 28 VDC, Ii=100 mA, Ci=1nF, Li=0,

Pi=0.7 W T

amb

= 60 ºC

Australia (TestSafe) Certificate No: Ex AUS Ex 3738X

Marking code: Ex ia IIC T5 IP65
AUS Ex 3738X

Safety factors V

max

= 28 VDC, Ii=100 mA, Pi= 0.7 W,

Ci=1nF, Li=0 mH

General

Operating voltage 12...28 V

with serial port (service mode) 15...28 V

Connections screw terminals, 0.33...2.0 mm2 wires

(AWG 14-22)
Cable bushing Pg11 (5...12mm)
Conduit fitting Pg11/NPT 1/2"-14
Operating temperature range for
electronics -40...+60 °C

with display and/or with

Storage temperature range -40...+70 °C
Housing material G-A1Si 10 Mg (DIN 1725)
Housing classification IP 65 (NEMA 4)
Housing dimensions 164 x 115 x 62 mm
Housing weight 950g
Fully electromagnetically compatible
according to standards EN 61326-1:1997 +Am :1998,

Electrical equipment for
measurement, control and laboratory
use - EMC requirements; Industrial
environment
Note ! IEC 1000-4-5 complies only
when using external EXi approved
surge arrester on safe area.

Specifications ______________________________________________________________________

Vaisala _________________________________________________________________________ 56

Probes

Probe cable length 2, 5, or 10 m
Probe cable diameter 5.5 mm
Sensor protection options stainless steel sintered filter

stainless steel filter
PPS grid with steel netting filter
PPS grid

HMP361 Probe - wall mount

Temperature range -40...+60 °C

HMP362 Probe - small pressure tight

Temperature range -40...+110 °C
Pressure range 0...16.7 MPa (0...167 bar)

HMP363 Probe - confined spaces

Temperature range -40...+120 °C

HMP364 Probe - high pressures

Temperature range -40...+180 °C
Pressure range 0...10 MPa (0...100 bar)

HMP365 Probe - high temperatures

Temperature range -40...+180 °C

HMP368 Probe - pressurized pipelines

Temperature range -40...+180 °C
Pressure range 0...4 MPa (0...40 bar)

Options and accessories

Display two-line LCD

character size (1st line/2nd line) 12 mm/10 mm

Calculated output variables dewpoint temperature

mixing ratio
absolute humidity

wet bulb temperature
Additional analog output 4...20 mA
Duct mounting installation kit
(for HMP363 sensor head) Order code: HMP233FAH
Installation flange (for HMP365
sensor head)

aluminum HMP235FA
stainless steel HMP235 FS

Accuracies of the calculated variables (not valid with HMT360 for Natural Gas) __________________

Vaisala _________________________________________________________________________ 57

Ball valve set (for HMP368
sensor head) DMP248BVS

pressure range at +20 °C 0...70 bar
Sampling cell HMP302SC
Serial interface cable for PC
connectors RJ45 - D9 female 25905ZZ
Rain shield HMT360SAR
Protection cover (for use in the presence
of combustible dust) 214101
HMK15 adapter fitting 211011
for 12 mm probes
Galvanic isolator (EU) 212483
Barrier (USA&Canada) 210664

ACCURACIES OF THE CALCULATED
VARIABLES (NOT VALID WITH HMT360 FOR

NATURAL GAS)

Accuracy of the calculated variables depend on the calibration accuracy of the
humidity and temperature sensors; here the accuracy are given for ±2
%RH and ±0.2 °C.

Accuracy of dewpoint temperature °C

Relative humidity

Temp.102030405060708090100

-40 1.86 1.03 0.76 0.63 0.55 0.50 0.46 0.43 — —

-20 2.18 1.19 0.88 0.72 0.62 0.56 0.51 0.48 — —
0 2.51 1.37 1.00 0.81 0.70 0.63 0.57 0.53 0.50 0.48
20 2.87 1.56 1.13 0.92 0.79 0.70 0.64 0.59 0.55 0.53
40 3.24 1.76 1.27 1.03 0.88 0.78 0.71 0.65 0.61 0.58
60 3.60 1.96 1.42 1.14 0.97 0.86 0.78 0.72 0.67 0.64
80 4.01 2.18 1.58 1.27 1.08 0.95 0.86 0.79 0.74 0.70
100 4.42 2.41 1.74 1.40 1.19 1.05 0.95 0.87 0.81 0.76
120 4.86 2.66 1.92 1.54 1.31 1.16 1.04 0.96 0.89 0.84
140 5.31 2.91 2.10 1.69 1.44 1.26 1.14 1.05 0.97 0.91
160 5.80 3.18 2.30 1.85 1.57 1.38 1.24 1.14 1.06 0.99

Accuracies of the calculated variables (not valid with HMT360 for Natural Gas)___________________

Vaisala _________________________________________________________________________ 58

Accuracy of mixing ratio g/kg

(ambient pressure 1013 mbar)

Relative humidity

Temp.102030405060708090100

-40 0.003 0.003 0.003 0.003 0.003 0.004 0.004 0.004 — —

-20 0.017 0.018 0.019 0.021 0.022 0.023 0.025 0.026 — —
0 0.08 0.09 0.09 0.10 0.10 0.11 0.11 0.12 0.13 0.13
20 0.31 0.33 0.35 0.37 0.39 0.41 0.43 0.45 0.47 0.49
40 0.97 1.03 1.10 1.17 1.24 1.31 1.38 1.46 1.54 1.62
60 2.68 2.91 3.16 3.43 3.72 4.04 4.38 4.75 5.15 5.58
80 6.73 7.73 8.92 10.34 12.05 14.14 16.71 19.92 24.01 29.29
100 16.26 21.34 28.89 40.75 60.86 98.85 183.66 438.56 — —
120 40.83 74.66 172.36 — — — — — — —

Accuracy of wet bulb temperature °C

Relative humidity

Temp.102030405060708090100

-40 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 — —

-20 0.21 0.21 0.22 0.22 0.22 0.22 0.23 0.23 — —
0 0.27 0.28 0.28 0.29 0.29 0.29 0.30 0.30 0.31 0.31
20 0.45 0.45 0.45 0.44 0.44 0.44 0.43 0.43 0.42 0.42
40 0.84 0.77 0.72 0.67 0.64 0.61 0.58 0.56 0.54 0.52
60 1.45 1.20 1.03 0.91 0.83 0.76 0.71 0.67 0.63 0.60
80 2.23 1.64 1.32 1.13 0.99 0.89 0.82 0.76 0.72 0.68
100 3.06 2.04 1.58 1.31 1.14 1.01 0.92 0.85 0.80 0.75
120 3.85 2.40 1.81 1.48 1.28 1.13 1.03 0.95 0.88 0.83
140 4.57 2.73 2.03 1.65 1.41 1.25 1.13 1.04 0.97 0.91
160 5.25 3.06 2.25 1.82 1.55 1.37 1.24 1.13 1.05 0.99

Accuracy of absolute humidity g/m³

Relative humidity

Temp.102030405060708090100

-40 0.004 0.004 0.005 0.005 0.005 0.006 0.006 0.006 — —

-20 0.023 0.025 0.027 0.029 0.031 0.032 0.034 0.036 — —
0 0.10 0.11 0.12 0.13 0.13 0.14 0.15 0.15 0.16 0.17
20 0.37 0.39 0.41 0.43 0.45 0.47 0.49 0.51 0.53 0.55
40 1.08 1.13 1.18 1.24 1.29 1.34 1.39 1.44 1.49 1.54
60 2.73 2.84 2.95 3.07 3.18 3.29 3.40 3.52 3.63 3.74
80 6.08 6.30 6.51 6.73 6.95 7.17 7.39 7.61 7.83 8.05
100 12.2 12.6 13.0 13.4 13.8 14.2 14.6 15.0 15.3 15.7
120 22.6 23.3 23.9 24.6 25.2 25.8 26.5 27.1 27.8 28.4
140 39.1 40.0 41.0 42.0 43.0 44.0 45.0 45.9 46.9 47.9
160 63.5 64.9 66.4 67.8 69.2 70.7 72.1 73.5 74.9 76.4

_________________________________________________________________________________

Vaisala _________________________________________________________________________ 59

APPENDIX 1: DIMENSIONS

HMT361

HMP362

Flange intersection

Sample cell HMP302SC

ø36 (1.42)

ø32 (1.26)

41(1.61)

M6

ø12 (0.47)

1/8"-27 NPT

9(0.35)

7 (0.28)

71.5 (2.8 1)

92.5 (3.64)

81 (3.19)

71 (2.80)

58.7 (2.31)

1

6

(0

.

6

3

)

ø

2

4

.

5

4

5

°

4

5°

4

5

°

M

6

ø12.5 (0.49)

1/8"-27 NPT

_________________________________________________________________________________

Vaisala _________________________________________________________________________ 60

HMP363

HMP364

HMP365

HMP368

_________________________________________________________________________________

Vaisala _________________________________________________________________________ 61

Mounting plate

Rain shield

180

80

15

_________________________________________________________________________________

Vaisala _________________________________________________________________________ 62

Protection cover

208

224

160

184

ø

8

.

2

189

96

82

2

_________________________________________________________________________________

Vaisala _________________________________________________________________________ 63

APPENDIX 2: WIRING FOR
INTRINSICALLY SAFE OPERATION, FM

Use FM approved associated apparatus;
zener barriers or galvanic isolators with
entity concept parameters:
V

oc

< 28 V

I

sc

<100 mA

C

a

> Ci + Ccable

L

a

> Li + Lcable

HMT360-series transmitters are approved
for use in Classes I, II ans III,
Division 1, groups A-G and
Division 2, Groups A-D, F and G.

Safety factors for HMT360-series transmitters
are:V

max

= 28 V, I

max

=100 mA,

C

i

= 1 nF, Li=0, Pi=0.7 W.

NOTE:

1. Barrier installation must be
completed in accordance with
ANSI/ISA RP 12.6 and the National
Electrical Code.

2. Intrinsically safe barrier ground
must be less than 1 ohm.

3. Maximum safe area voltage is 250 V.

Material Weight Finish

Part list

General tolerance

laces

laced

e

pted

dle

r

ator

cked

Scale

Title

Status

Code

Rev

01-09-04 ARH

1:1

CONTROL DRAWNING

DRW211603 A

Load Ch1

Vmax=28VDC

Vmax=28VDC

Load Ch2

Vaisala Oyj
Vanha Nurmijärventie 21
Vantaa
Finland

HAZARDOUS AREA SAFE AREA

ch1 ch2

_________________________________________________________________________________

Vaisala _________________________________________________________________________ 64

APPENDIX 3: WIRING FOR INTRINSICALLY
SAFE OPERATION

, CSA

R

eplaced

by

D

rawn

eview

ppr

esign

eplaces

Scale

id

Title

Arch

no

Serial

Sheet

doc no

Cooper ator`s

Dwg no

R

e

NOTE:

1. Each channel must be supplied through separate
shielded cables.

2. When using galvanic separators CH1- and CH2­must be short circuited with an external wire.

3. When using transmitter in Class I, Division 2 the
main switch shall not be operated or the unit shall not
be disconnected unless power has been switched off,
or area is known to be non hazardous.

4. Use only conduit connection in Division 2.

5. Substitution on components may impair intrinsic
safety or suitability for Division 2.

6. Only intrinsically safe installation is allowed in Class II
and Class III environments.

7. Intrinsically safe barrier ground must
be less than 1 ohm.

8. Maximum safe area voltage is 250V.

p

HMT360-series transmitters are approved for use in
Division 1 and 2, Class I, Groups A, B, C, and D.
Division 1, and 2, Class II, Group G and coal dust.
Division 1, and 2, Class III.

Vaisala Oyj
Vanhanurmijärventie 21
Vantaa
Finland

Installati on
Drawing

DRW213478

HAZARDOUS AREA SAFE AREA

HMT360 connec tion board

-Ch1+ -Ch2+

Load Ch2

Vmax=28VD C

Vmax=28VD C

Load Ch1

KKe 2002-08-21

HMT360-series transmitters shall be used with
following probes:
Probe HMP361 with 116mm lenght pipe.
Probe HMP363 with 2, 5 or 10 m lenght cable.
Probe HMP364 with 2, 5 or 10 m lenght cable.
Probe HMP365 with 2, 5 or 10 m lenght cable.
Probe HMP368 with 2, 5 or 10 m lenght cable.

The material for associated cable is FEP
(Tetrafluoropropylene).

To avoid static discharge shall the cable cover wi

t

conductive material.

HMT360-series transmitters shall be used with
following zener barrier or galvanic separator types:

Manufacturer: Type:
R. Stahl 9001/51-280-091-14
R. Stahl 9002/13-280-093-00
R. Stahl 9303/11-22-11
MTL MTL7206
MTL MTL5044

Cable parameters shall be less than 60pF/ft (197pF/m)
and 0.2µH/ft (0.67µH/m). The maximum cable lenght
is 2000ft (600m).

Max cable lenght 2000ft (600m)

A

_________________________________________________________________________________

Vaisala _________________________________________________________________________ 65

CERTIFICATES

_________________________________________________________________________________

Vaisala _________________________________________________________________________ 66

_________________________________________________________________________________

Vaisala _________________________________________________________________________ 67