Vaisala HMP140 User Manual
USER'S GUIDE
Vaisala HUMICAP® Humidity
Transmitter Series
HMP140A
U175EN15
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.
HMP140A SERIES
U175en-1.5 Operating Manual
Contents
1. PRODUCT DESCRIPTION ...................................................................................................1
2. TO BE NOTED WHEN M EASURING HUMIDITY ..................................................................2
3. INSTALLATION....................................................................................................................3
3.1 Selecting the place of installation ..........................................................................3
3.2 Mounting..................................................................................................................3
3.2.1 Mounting the HMP141A .............................................................................4
3.2.2 Mounting the HMP142A .............................................................................4
3.2.3 Mounting the HMP143A .............................................................................5
3.3 Electrical connections.............................................................................................6
3.4 Connectors and potentiometers on the main PCB................................................7
3.5 Selecting the outputs..............................................................................................7
3.6 Connection to an AC supply..................................................................................8
4. CALIBRATION .....................................................................................................................9
4.1 One-point humidity calibration...............................................................................9
4.2 Two-point humidity calibration...............................................................................9
4.2.1 Two-point humidity calibration procedure ...................................................9
4.3 Temperature calibration........................................................................................10
4.4 Calibration table.................................................................................................... 11
5. MAINTENANCE..................................................................................................................11
5.1 Replacing the HUMICAP
6. TECHNICAL DATA.............................................................................................................12
6.1 Relative humidity...................................................................................................12
6.2 Temperature...........................................................................................................12
6.3 General...................................................................................................................13
6.4 Electromagnetic compatibility..............................................................................14
6.4.1 Emissions................................................................................................14
6.4.2 Interference.............................................................................................14
7. SPARE PARTS AND ACCESSORIES ................................................................................14
180 sensor and the filter ............................................11
APPENDIX 1: CURRENT OUTPUT MODULE
APPENDIX 2: SETTINGS OF THE LOCAL DISPLAY
APPENDIX 3: HMP143A PROBE CABLE EXTENSION
TECHNICAL DATA
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HMP140A SERIES
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1. PRODUCT DESCRIPTION
The HMP140A series transmitters are reliable and easy to use instruments for
the measurement of relative humidity and temperature. The series consists of
three different types of transmitters to be chosen according to the requirements
of the application:
• HMP141A for wall installations
• HMP142A for duct installations
• HMP143A for installation in tight places
The configuration can be chosen from various possibilities to meet the specific
requirements of the customer. The transmitters can be ordered with a blank
cover or a cover with a local display which outputs relative humidity and
temperature readings. The reading to be displayed is chosen with a pushbutton
on the cover and the desired temperature unit (Celsius or Fahrenheit) can be
chosen with a jumper (see Appendix 2).
All HMP140A transmitters measure relative humidity in the range of
0...100 %RH and temperature from -40 to +60 °C; the measurement is
temperature compensated. The HMP140A transmitters have four different
analogue outputs: 0...20 mA (4...20 mA), 0...1 V, 0...5 V and 0...10 V. The
outputs are also scalable if necessary, e.g. 4...20 mA from 0...20 mA.
The durable plastic cover provides IP65 protection from dust and sprayed
water. The HMP140A transmitters are therefore suitable for most indoor and
outdoor applications, including those with high humidities like indoor
swimming pools etc. These versatile transmitters are also easy to install and to
use. When necessary, they can be recalibrated on site with Vaisala’s HMI41
indicator equipped with an appropriate probe and optional calibration cable
(19116ZZ).
The HMP140A series transmitters incorporate the HUMICAP180 sensor, the
operation of which is based on the changes in its capacitance as the thin
polymer film absorbs water molecules. The sensor is immune to most
chemicals and has an excellent long-term stability. The temperature is
measured with a Pt 1000 sensor.
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Operating Manual U175en-1.5
2. TO BE NOTED WHEN MEASURING HUMIDITY
In the measurement of humidity and especially in calibration, it is essential
that the temperature equilibrium is reached. Even a slight difference in the
temperature between the measured object and the sensor causes an error. For
example, at +20 °C (+ 68 °F) and 50 %RH, a temperature difference of +1 °C
between the measured object and the sensor causes an error of +3 %RH. If
relative humidity is 90 %RH, the error is about +5.4 %RH.
The error is at its greatest when the temperature of the sensor differs from that
of the surroundings and the humidity is high. A few degrees’ difference in
temperature may cause water to condense on sensor surface. Efficient
ventilation accelerates evaporation whereas in an unventilated space, it may
take hours. The HUMICAP180 sensor returns to its normal functioning as
soon as water has evaporated. Any contaminated water condensing on the
sensor may shorten its life span and change the calibration.
10
9
8
7
6
5
4
dRH (%RH)
3
2
1
0
-40-200 20406080100
Temperature (°C)
Figure 2.1 Measurement error at 100 %RH when the temperature
difference between th e ambient and the sensor i s 1 °C
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HMP140A SERIES
U175en-1.5 Operating Manual
3. INSTALLATION
3.1 Selecting the place of installation
Select a place that gives a true picture of the environment or process and is as
clean as possible. Air should circulate freely around the sensor. A rapid air
flow is recommended as it ensures the same temperature for the ambient air
and the sensor head.
Install the transmitter in a place where no cold or hot spot can develop. If the
sensor head is installed in a duct or channel where the temperature is different
from the ambient temperature, insulate the point of entry; this is particularly
important if the transmitter is installed with the sensor head pointing
downwards. Vertical installation of the HMP142A and HMP143A is not
recommended; they should be mounted with the sensor head horizontally
whenever possible. An uninsulated installation might lead to condensation on
the sensor head and even if no condensation occurs, the resultant air flow may
change the temperature near the sensor head and distort the readings.
3.2 Mounting
The electronics of the HMP140A series can be disconnected for ease of
installation and service. The housing can be conveniently installed and the
electronics then consequently mounted. For service and maintenance purposes
the electronics can be disconnected without disconnecting the cabling, and
taken to an appropriate environment for necessary adjustments.
60
6.5
60
83.5
4.2
Figure 3 Drilling dimensions (in mm)
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HMP140A SERIES
Operating Manual U175en-1.5
3.2.1 Mounting the HMP141A
The optimal installation of the HMP141A is with the sensor head pointing
downwards. Upward mounting should be avoided due to internal heat transfer.
1. Mounting and wiring:
cable feedthrough
on the surface or
in the connection box.
2. Mount the protection
lid to the conn ection
box.
3. Push the s e nsor h ea d
through the protection
lid a s in fig ure a n d
connect the electronics
housing to the connection
box. Make sure that the
pins at the bottom of
the electronics housing
are in co nt ac t with the
sc r ew termin a l .
4. Fasten the four
conn ec ting s cre w s of
the electronics housing.
5. Place the sensor head
into the p ro t e ct io n lid .
6. Close the cover and fasten
the two co n ne c tion s c rews.
1
3
4
4
6
4
4
5
2
Figure 3.2.1 Mounting of the HMP141A
3.2.2 Mounting the HMP142A
The HMP142A transmitter should be mounted with the sensor head
horizontally whenever possible. This way, any water that might condense on
the tube cannot flow on to the sensors. When there is no alternative but to
install the sensor head in the process vertically, the point of entry must be
carefully insulated.
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HMP140A SERIES
U175en-1.5 Operating Manual
225
Ø 15
Ø 12
Figure 3.2.2 Dimensions of the HMP142A (in mm)
3.2.3 Mounting the HMP143A
The cable model HMP143A should also be mounted with the sensor head
horizontally whenever possible. This model is provided with two plastic nuts
and a gasket. Mount the nuts on the sensor head: disconnect the cable from the
transmitter, insert the nuts and fasten them on the sensor head. Then reconnect
the cable. A mounting flange is also available (see Fig. 3.2.3). The cable can
also be extended up to 100 metres; see Appendix 3 for details.
M12x1
Ø 12
69
duct wall
sealing
supporting bar
a plugged hole for
reference measurements
flange
Figure 3.2.3 Dimensions of the HMP143A probe (in mm) and
installation in a channel with the help of flange
(part no. HMP233FA) and supporting bar
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