Vaisala HMD20 User manual

USER'S GUIDE
Calibration of Series HMD/W20/30 and
HMP130 Transmitters with
Vaisala HUMICAP® Indicator HMI41
U220EN11

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 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.

HMI41 Calibration Option
19165ZZ-U220en-1.1 Operating Manual
1996-08-29 i
Contents
1. INTRODUCTION......................................................................................................................1
1.1 HMI41 with calibration option ......................................................................................1
1.2 Selecting the HMI41 calibrator function ......................................................................1
2. CALIBRATION.........................................................................................................................3
2.1 Getting started ..............................................................................................................3
2.2 Calibration.....................................................................................................................4
APPENDIX 1: QUICK REFERENCE GUIDE

HMI41 Calibration Option
Operating Manual 19165ZZ-U220en-1.1
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HMI41 Calibration Option
19165ZZ-U220en-1.1 Operating Manual
1996-08-29 1
1. INTRODUCTION
1.1 HMI41 with calibration option
The HMI41 can be used as a field calibrator for various Vaisala humidity
transmitters. There are three different calibration cables available:
•19116ZZ for the calibration of Vaisala’s HMD/W 60/70 and
HMP140 series analogue transmitters
•19164ZZ for the calibration of HMP230 series digital transmitters
•19165ZZ for the calibration of the HMD/W 20/30 and
HMP130 series analogue transmitters
In this manual, only the calibration of HMD/W 20/30 and HMP130 series
analogue transmitters is dealt with. For other calibration options, please refer
to corresponding manuals.
Calibration is quick and easy to perform. In calibration, the HMI41 measures
relative humidity with the reference probe and receives the RH information
from the transmitter. These two values are then compared on the HMI41
display and the transmitter is adjusted with calibration potentiometers inside
the transmitter.
1.2 Selecting the HMI41 calibrator function
The desired calibrator function is selected in the HMI41 setup menu. To enter
the setup mode, first press the ON/OFF button and the following appears:
RH
setminmax hysthold LobatHi
PPahg/m
T
Td
°C °F
°C °F
%
Then release the ON/OFF button and within 1...2 seconds press both ENTER
and MODE buttons until the following text appears on the display:
After a few seconds, the text changes automatically to show the following:

HMI41 Calibration Option
Operating Manual 19165ZZ-U220en-1.1
21996-08-29
set
°C
If the basic settings of the HMI41 (display units, automatic power off
function, display quantities and pressure) have to be changed, please refer to
the HMI41 Operating Manual. Otherwise, press ENTER repeatedly until the
following text appears:
set
The number on the first line of the display corresponds to the following
HMI41 functions:
1 = HMI41 as a humidity and temperature indicator
2 = HMI41 as a calibrator for HMD/W 60/70 and HMP140 series analogue
transmitters
3 = HMI41 as a calibrator for HMP230 series digital transmitters
4 = HMI41 as a calibrator for the HMD/W20/30 and HMP130 series
analogue transmitters
To calibrate the HMD/W 20/30 or HMP130 series transmitters, select number
4 with buttons ▲(number up) and ▼(number down) and then turn the HMI41
off. When the HMI41 is turned on again, it will automatically assume the
calibrator function for the HMD/W 20/30 and HMP130 series transmitters. If
you wish to calibrate transmitters of some other type or use the HMI41 as an
indicator, this selection has to be made accordingly; refer to corresponding
manuals for further details.

HMI41 Calibration Option
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2. CALIBRATION
For a successful calibration, it is essential that the probe of the HMI41 and
that of the transmitter are at the same temperature, and that the reference
probe has been previously calibrated. Always allow enough time for the
readings to stabilize. Note that the stabilization time depends on the ambient
conditions and may vary from 10 minutes to a couple of hours.
2.1 Getting started
After having selected the desired function (Chapter 1.2), turn the HMI41 off
and connect the calibration cable to the EXT connector at the bottom of the
HMI41 (Figure 2.1). Connect the other end of the cable to the appropriate
connector in the transmitter (Figures 2.2 - 2.4).
ENTE R MOD E H O L D O N / OFF
EXT
Connector for the
calibration cable
Figure 2.1 Location of the HMI41 calibration connector
one point
RH calibration
test connector
Figure 2.2 Calibration connector and potentiometer in
the HMP130 series transmitters

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offset
gain
test
connector
Figure 2.3 Calibration connector and potentiometers in
the HMD 20/30UB/YB transmitters
gain
offset
test
connector
Figure 2.4 Calibration connector and potentiometers in
the HMW 20/30UB/YB transmitters
2.2 Calibration
After having connected the cable, turn the HMI41 on with the ON/OFF button
and wait until a text similar to the following appears on the display:
RH %
Numbers on the first line indicate the RH measured by the transmitter, and
numbers on the second line indicate the RH measured by the HMI41 reference
probe. If you wish, you can now adjust the transmitter:
•Wait until the readings have stabilized and adjust the calibration
potentiometers (Figures 2.2 - 2.4) until the readings on the first and
the second line are the same. It is recommended to use the offset
potentiometer if the RH is <65 %RH and the gain potentiometer if the
RH is >65 %RH.

HMI41 Calibration Option
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1996-08-29 5
•After having completed the calibration, press ON/OFF and disconnect
the cable.
If you prefer, you can change the HMI41 display to show the difference in the
readings and then adjust the transmitter. To do this, press MODE when both
readings are on the display and a text similar to the following is displayed:
RH %
Numbers on the first line indicate how much the RH measured by transmitter
differs from that of the reference probe. Numbers on the second line indicate
the RH measured by the reference probe. If you wish, you can now calibrate
the transmitter (by pressing MODE again the measured values appear on the
display):
•Wait until the readings have stabilized and adjust the calibration
potentiometers (Figures 2.2 - 2.4) until the numbers on the first line
are as close to zero as possible. It is recommended to use the offset
potentiometer if the RH is <65 %RH and the gain potentiometer if the
RH is >65 %RH.
•After having completed the calibration, press ON/OFF and disconnect
the cable.
GUARANTEE
Vaisala issues a guarantee for the material and workmanship of this product
under normal operating conditions for one (1) year from the date of delivery.
Exceptional operating conditions, damage due to careless handling and mis-
application will void the guarantee.

HMI41 Calibration Option
19165ZZ-U220en-1.1 Appendix 1
1996-08-26 1
APPENDIX 1: QUICK REFERENCE TO CALIBRATION
It is recommended that this quick reference guide is used only as a checking
list for those who already know how to operate the HMI41 as a calibrator. For
those who take it into use for the first time, the Operating Manual gives useful
information that is not included in this quick reference guide.
1. Selecting the calibrator function
For selecting the calibrator function, press ON/OFF until you can see some
text on the display. Then release the ON/OFF button and press within 1...2
seconds both ENTER and MODE buttons until the text "setup" appears on the
display. Then follow the instructions of the table below.
DISPLAY WHAT TO DO PRESS:
Wait for a few seconds.
set
°C
If the basic settings have been given,
press ENTER.
If they have not been given, refer to the
HMI41 Operating Manual.
press ENTER repeatedly:
set
select the HMI41 function:
1 = indicator
2 = calibrator for HMD/W 60/70 and
HMP140 series analogue transmitters
3 = calibrator for HMP230 transmitters
4 = calibrator for HMD/W20/30 and
HMP130 series transmitters
▲(number up) or
▼(number down)
ON/OFF