Vaisala HMI41 Operating Manual
r
OPERATING MANUAL
HMI41 Indicato
and HMP42 Probe
U323en-1.1
© Vaisala Oy 1998
No part of this document 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 a prior written
notice of the copyright holder.
The instruction manuals may be changed without prior notice.
Yleisjäljennös 3/1998
HMI41 AND HMP42
U323en-1.1 Operating Manual
Contents
1. THE HMI41 INDICATOR AND PROBES..................................................................................1
2. TO BE NOTED IN THE M EASUREMENT OF HUM IDIT Y ......................................................... 3
3. GETTING STARTED................................................................................................................ 4
3.1 Inserting the batteries .................................................................................................. 4
3.2 Connecting the HMP42 probe ...................................................................................... 4
3.3 Starting the measurements..........................................................................................4
3.4 Using the HMP42 for measuring equilibrium humidity in structures.........................5
3.4.1 Example 1: measuring hum idity in a bathroom ................................................5
3.4.2 Example 2: measuring hum idity in a concrete floor..........................................6
3.4.3 Erroneous installations .................................................................................... 7
4. HOW TO USE THE HM I41 INDICATOR AND HMP42 PROBE ................................................. 8
4.1 Turning the indicator on............................................................................................... 8
4.2 Measurement readings on display ............................................................................... 9
4.3 HOLD-mode................................................................................................................. 10
4.3.1 MIN-mode ..................................................................................................... 10
4.3.2 MAX-mode .................................................................................................... 10
5. CALIBRATION....................................................................................................................... 11
5.1 How to use the HMP42 calibration adapter ............................................................... 11
5.2 Calibration with trimmer potentiometers .................................................................. 12
5.2.1 Humidity calibration....................................................................................... 12
5.3 Calibration with HMI41 software commands............................................................. 14
5.3.1 One point humidity calibration........................................................................ 16
5.3.2 Two point humidity calibration........................................................................ 18
5.3.3 One point temperature calibration.................................................................. 20
5.3.4 Two point temperature calibration.................................................................. 22
6. HMI41 AND DATA COLLECTING.......................................................................................... 25
6.1 Entering the data collecting mode............................................................................. 25
6.2 Manual data collecting ...............................................................................................26
6.3 Setting the measurement duration ............................................................................ 27
6.4 Setting the measurement interval.............................................................................. 27
6.5 Reading the measurement results............................................................................. 28
6.5.1 MIN and MAX in data collecting
REC READ mode............................................ 30
7. TRANSFERRING THE STORED READINGS TO A PC.......................................................... 31
7.1 Giving the communication parameters ..................................................................... 31
7.2 Transferring the data.................................................................................................. 34
7.2.1 PLAY Transferring the data ........................................................................... 34
7.2.2 CPLAY Setting characters between decimals and fields ................................ 35
7.2.3 HELP Outputting all available commands and their contents ..................... 36
7.3.4 ? Outputting the HMI41 settings .................................................................... 36
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Operating Manual U323en-1.1
8. SETUP PROCEDURE ............................................................................................................37
8.1 Entering the setup mode ............................................................................................37
8.2 Selecting the display units......................................................................................... 38
8.3 Setting the automatic power-off function..................................................................39
8.4 Selecting the display quantities.................................................................................39
8.5 Setting the pressure for mixing ratio and wet bulb temperature calculations .......40
8.6 Selecting the probe type.............................................................................................40
9. MAINTENANCE .....................................................................................................................41
9.1 Changing the filter and the sensor head set ............................................................. 41
9.2 Chemical tolerances of the HUMICAP
MINI sensor ..................................................41
9.3 Spare parts and accessories...................................................................................... 42
10. IN CASE OF ERROR............................................................................................................43
10.1 Trouble shooting .......................................................................................................43
10.2 Checking the settings............................................................................................... 44
11. TECHNICAL DATA............................................................................................................... 45
11.1 HMI41 indicator .........................................................................................................45
11.2 HMP42 probe .............................................................................................................46
11.2.1 Relative humidity........................................................................................... 46
11.2.2 Temperature................................................................................................ 46
11.2.3 General........................................................................................................47
11.4 Accuracy of the calculated quantities......................................................................48
11.4.1 Accuracies in metric units ............................................................................ 48
11.4.2 Accuracies in non-m etric units ..................................................................... 49
11.5 Electromagnetic compatibility..................................................................................51
11.5.1 Emissions....................................................................................................51
11.5.2 Immunity......................................................................................................51
APPENDIX 1: QUICK REFERENCE GUIDE ...............................................................................53
WARRANTY...................................................................................................................................
This manual is valid for programme versions 2.01 or greater.
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U323en-1.1 Operating Manual
1. THE HMI41 INDICATOR AND PROBES
The HMI41 is an easy-to-use portable humidity and temperature indicator for
a variety of applications, including such as industrial monitoring and
inspections, occupational health and safety, laboratory and research use, spot
checking etc. When equipped with optional calibrati on cables, the HMI41 can
also be used as a field calibrator for most Vaisala transmitters.
The HMI41 has as many as six different probe types to choose from. The
indicator recognizes the probe type automatically, so there is no need to
change settings each time the probe is changed. However, please, note that this
feature is active only in indicators and probes with letters ID in the instrument
label. For previous versions, the probe type has to be set manually. The
HMP44 is an exception, as indicators marked with ID recognize automatically
all versions of this probe. All probe types are optimized for different
applications:
• HMP41 probe can be used for measuring humidity and temperature in
numerous applications, for example in spot checks.
• HMP42 probe head has a diameter of only 4 mm. The HMP42
consists of a handle a 23.5 cm long probe head. This remarkably small
and round probe structure is specially indicated for measurements in
very tight spaces, e.g. in joint spaces between tiles and in air
conditioning channels, as well as for measuring the equilibrium
humidity of e.g. timber; the operating temperature range is
-40 - +100 °C.
• HMP44 and HMP44L are used for measuring humidity in concrete
and other structures.
• HMP45 probe is indicated for measurements in channels and other
places that are difficult to reach and therefore require a probe head
with cable.
• HMP46 probe is optimized for measurements in relatively high
temperatures (up to +100 °C, temporarily even +180 °C), in dirty
processes and in general in applications that require a robust probe
structure.
The HMI41 indicator displays relative humidity, temperature and dewpoint
temperature readings. In addition to these, one of the following quantities can
also be chosen: absolute humidity, wet bulb temperature or mixing ratio.
The indicator also features an automatic power-off function which can be
disabled, and a continuously updated display. The display can be frozen to
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Operating Manual U323en-1.1
show the current readings, and it can be used for checking the minimum and
maximum readings measured during data collecting. The automatic power-off
function is not active during data collecting even if it was previously selected.
The versatile HMI41 indicator also includes a data collecting feature. Data
collecting can be either automatic or manual, and it can be optimized for each
application: both the measurement interval and duration can be set by the user.
During automatic data collecting, the probe takes measurements only just
before storing each measurement. In order to minimize the consumption and to
maximize the battery life, the power is automatically turned off for the
measurement interval and the display is dim except when the readi ngs on the
display are updated (once a minute). The stored readings can be transferred to
a PC via a serial interface (order code 19446ZZ) and then printed, if required.
The humidity measurement range is 0 - 100 %RH. The temperature measure-
ment range with the HMP42 probe is -40 - +100 °C. Relative humidity is
measured with the accurate and stable HUMICAPMINI humidity sensor
which uses an operating principle based on the changes in the capacitance of
the sensor as its thin polymer film absorbs water molecules.
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U323en-1.1 Operating Manual
2. TO BE NOTED IN THE MEASUREMENT OF HUMIDITY
In the measurement of humidity and especially in calibration it is essential that
temperature equilibrium is reached. Even a small difference in temperature
between the measured object and the sensor causes an error. If the t emperature
is +20 °C (+68 °F) and the relative humidity is 50 %RH, a difference of +1 °C
between the measured object and the sensor causes an error of +3 %RH. When
the humidity is 90 %RH, the corresponding error is + 5.4 %RH.
The error is at its greatest when the sensor is colder or warmer than the
surroundings and the humidity is high. Although the humidity sensor reacts
rapidly to changes in the amount of water vapour in the air, the probe
temperature changes more slowly. To avoid errors caused by temperature
differences the probe must always be left to stabilize to ambient temperature
before starting measurements: the bigger the temperature difference, the
longer the stabilization time.
Indoors relative humidity should be measured in a place where the temperature
is as close to the average temperature of the room as possible. Measurements
taken close to heat sources will not give a true picture of the relative humidity
in the whole room.
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 dif ference
between the ambient and the sen sor temperature is 1 °C
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Operating Manual U323en-1.1
3. GETTING STARTED
3.1 Inserting the batteries
When taking the HMI41 indicator into use, first insert the batteries (4 pcs of
size AA [LR6] batteries). Open the lid on back of the device and insert the
batteries as indicated in the housing. Then close the lid carefully.
3.2 Connecting the HMP42 probe
Connect the HMP42 probe cable to the connector marked 'PROBE' at the
bottom of the HMI41 indicator (see Figure 3.2.1).
NOTE
If the indicator does not have letters ID in the
instrument label (on the back of the indicator), you
must give the probe setting manually before starting the
measurements (see Chapter 8).
HMP42
cable
Figure 3.2.1 Connecting the HMP42 probe to the HMI41
3.3 Starting the measurements
Before starting the measurements with the HMP42, remember to allow enough
time for stabilization.
Turn the power on with the ON/OFF button and the following appears:
RH
Td
T
P
set min max hyst hold Lo bat Hi
%
°C °F
°C
°F
Pahg/m
Within a couple of seconds, the display changes to show the software version
and the probe type (42.46):
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U323en-1.1 Operating Manual
NOTE: if the following appears, check that the probe is correctly connected:
If the software version does not appear, it is smaller than 1.02 and the
indicator cannot be used with the HMP42 probe. If the probe type does not
appear, the indicator is of a previous version and does not recognize the probe
type automatically; give the setting manually (see Chapter 8).
In a couple of seconds, the battery charge appears and after that, the first
measurement readings:
RH
T°C
More detailed instructions of use are given in Chapter 4.
%
3.4 Using the HMP42 for measuring equilibrium humidity in structures
The HMP42 has been optimized for taking measurements in structures and
tight places. The following photos illustrate some examples of use in these
applications.
3.4.1 Example 1: measuring humidity in a bathroom
In this example, the screw of the shower holder is removed; no drilling is
needed as the HMP42 is small enough to enter this screw hole.
Figure 3.4.1 Taking measurements in a bathroom
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Operating Manual U323en-1.1
3.4.2 Example 2: measuring humidity in a concrete floor
Bore a hole and clean it thoroughly so that all drilling dust comes out; blowing
air is a good method for cleaning. However, please, note that if you clean
several holes, you should use a mask to protect yourself against dust. You can
also use a vacuum cleaner. Seal the hole e.g. with tape. Let stabilize (e.g. 24
hours in concrete). Cut the tape, insert the probe in the hole and take
measurements. See photos below for steps 1 - 6.
1. Bore a hole. 2. Clean it. 3. Seal it and let stabilize.
4. Cut the tape. 5. Insert the probe. 6. Take measurements.
Figure 3.4.2 Taking measurements in concrete floors
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HMI41 AND HMP42
U323en-1.1 Operating Manual
3.4.3 Erroneous installations
Please, note that although with a metal probe head, the HMP42 is a delicate
instrument and requires careful handling. The probe must never be strongly
bent or forced through anything; if necessary, use e.g. a sharp edged pin with a
diameter of 5 mm. The filter must not be twisted. When taking measurements
in structures, never leave the cable and indicator hanging down while leaving
the probe to stabilize (see photos below). Make sure that when mounted
horizontally, the probe is at least 4 cm inside the structure in order to avoid
bending. See the following photos and make sure that your installation is not
like the one on the right.
at least 4 cm
inside the
structure
Figure 3.4.3 Installation: correct way on the left,
erroneous on the right
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Operating Manual U323en-1.1
4. HOW TO USE THE HMI41INDICATOR AND HMP42 PROBE
4.1 Turning the indicator on
To start the measurements with the HMI41, just press the ON/OFF button and
the following text appears:
RH
Td
T
P
set min max hyst hold Lo bat Hi
%
°C °F
°C
°F
Pahg/m
After a few seconds, the software version and probe type indication appear:
If the software version does not appear, it is smaller than 1.02 and the HMI41
cannot be used with the HMP42. Contact Vaisala or a Vaisala representative
for further information.
Make sure that you can see the text 42.46 on the display. If not, the indicator
is of a previous version and does not recognize the probe type automatically.
Give the probe type setting manually (see Chapter 8).
After a couple of seconds, the battery voltage appears on the display with an
indication of the battery charge (high or low):
Hi
bat
If the battery voltage is higher than 4.75 V, the text on the lower righthand
corner is “bat HI” and after a few seconds, the HMI41 automatically displays
the RH and T readings. If the voltage is 4.65...4.75 V, the text is “Lo bat” and
the batteries should be replaced (see Chapter 3.1). If the voltage is lower than
4.65 V, the indicator turns itself off to prevent erroneous measurements and
readings. Should this happen, replace the batteries.
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HMI41 AND HMP42
U323en-1.1 Operating Manual
4.2 Measurement readings on display
Relative humidity and temperature readings appear automatically after the
battery charge indication:
RH
%
T°C
If MODE button is pressed, dewpoint temperature (Td) reading is displayed:
Td
T
When the MODE button is pressed again, one of the following is displayed or
°C
°C
the HMI41 returns to showing the RH and T readings according to what has
been chosen for the measurement quantities (see Chapter 4.4):
°C
g/m
Temperature and absolute humidity
T
abs
T
°C
°C
Temperature and wet bulb temperature; the
arrow in the lower righthand corner indicates that
wet bulb temperature has been chosen
T
°C
Temperature and mixing ratio; the arrow in the
lower righthand corner indicates that mixing ratio
has been chosen (the unit is g/kg or gr/lb).
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HMI41 AND HMP42
Operating Manual U323en-1.1
4.3 HOLD-mode
In any of the previously mentioned measurement reading displays, the HOLD
button freezes the display to show the current readings, e.g. RH & T readings:
RH
T
With MODE or ENTER, the display returns to the normal display mode.
If the indicator turns itself off with the automatic power-off function during
%
°C
hold
the HOLD-mode, it wakes up in the same mode when turned on again. The
'hold'-text is blinking and the indicator can be returned to the normal display
mode with any button except ON/OFF.
4.3.1 MIN-mode If you wish to know the minimum readings that have been measured after
power up, press HOLD when the indicator is in the HOLD-mode. The
minimum readings of the currently displayed quantities are shown (if the
‘hold’-text is blinking, the HMI41 must first be returned to the normal display
mode in order to activate the MIN-mode; see Chapter 4.3 above):
RH
T
min
With MODE or ENTER, the indicator returns to the normal display mode.
4.3.2 MAX-mode If you wish to know the maximum readings that have been measured after
%
°C
power up, press HOLD when the indicator is in the MIN-mode. The maximum
readings of the currently displayed quantities are shown:
RH
T
max
The indicator returns to the normal display mode with any button except
%
°C
ON/OFF.
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HMI41 AND HMP42
U323en-1.1 Operating Manual
5. CALIBRATION
5.1 How to use the HMP42 calibration adapter
As the HMP42 probe diameter is extremely small, the probe has a special
calibration adapter for inserting the probe into a salt chamber (e.g. in the
HMK15 calibrator).
NOTE
Be extremely careful when inserting the probe into the
calibration adapter: do not bend or break it.
The probe is inserted into the adapter with the steel grid on; this protects the
sensor and prevents it from breaking. Unlike other humidity probes, the
HMP42 is calibrated with the steel grid on and thus, the probe naturally
requires a slightly longer stabilization time (approx. 30 minutes).
Figure 5.1.1 HMI41, HMP42 and calibration accessories
Figure 5.1.2 Insert the probe head into the calibration adapter
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Operating Manual U323en-1.1
5.2 Calibration with trimmer potentiometers
5.2.1 Humidity calibration The HMI41 indicator and HMP42 probes are fully calibrated at the factory, so
there should be no immediate need for re-calibration. Calibration should be
performed only if there is a strong reason to believe that the adjustments have
changed.
Humidity calibration of the HMP42 probe is done by adjusting trimmer
potentiometers. The potentiometers are located under a protective plug. The
potentiometer marked T (temperature) is for factory use only; DO NOT make
any adjustments. To make sure that this potentiometer is not accidentally
touched when adjusting the other two, turn the plastic plug aside without
removing it completely (see Figure 5.2.1).
For adjusting the potentiometers, use a trimming wrench provided with the
probe, or some other suitable tool, e.g. a ceramic 1.5 mm slot screwdriver.
12
T
wet
W
D
W
D
dry
Figure 5.2.1 Adjusting the trimmer potentiometers
A two point calibration is performed with the HMK15 or the HMK13B
Calibrator or the probe can be sent to Vaisala. The probes must always be recalibrated if the sensor head set is changed.
HMI41 AND HMP42
U323en-1.1 Operating Manual
The calibration procedure is as follows (see also the calibrator manual):
• Leave the calibrator and the probe at the calibration site for at least 30
minutes before starting the calibration in order to let the probe
temperature stabilize to the room temperature.
• Insert the probe into a measurement hole of the LiCl salt chamber (see
Figure 5.2.2).
Figure 5.2.2 The HMP42 in a salt chamber of the
HMK15 calibrator
• Wait until the humidity reading stabilizes (approx. 30 minutes).
Check the temperature and read the closest humidity value in the
calibration table. Adjust the dry end reading with the potentiometer D
(dry) in the probe body to correspond to the value given in the
calibration table; use a suitable trimming screw wrench (see Figure
5.2.1).
• Insert the thermometer into the 13.5 mm hole of the NaCl salt
chamber and the probe into another hole of the NaCl chamber.
NOTE
When calibrating probes that are being used for long
term measurements (over 1 hour) in high humidities
(90 - 100 %RH), use the K2SO4 salt as the high end
reference.
• Wait until the humidity reading stabilizes. Read the salt chamber
temperature from the thermometer and then the closest humidity value
from the calibration table. Adjust the wet end reading with the
potentiometer W (wet) to correspond to the value given in the
calibration table.
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Operating Manual U323en-1.1
Table 5.2 Greenspan’s calibration table
°C
LiCl NaCl K2SO
4
0 * 75.5 98.8
5 * 75.7 98.5
10 * 75.7 98.2
15 * 75.6 97.9
20 11.3 75.5 97.6
25 11.3 75.3 97.3
30 11.3 75.1 97.0
35 11.3 74.9 96.7
40 11.2 74.7 96.4
45 11.2 74.5 96.1
50 11.1 74.4 95.8
* If the LiCl solution is used or stored in temperatures below +18°C, its equilibrium
humidity changes permanently
As the D (dry) and W (wet) adjustments may affect each other, check again
the humidity reading in the LiCl salt chamber: insert the probe into the
calibration hole and wait until the reading stabilizes. If necessary, repeat the
adjustments in both the LiCl and the NaCl (K2SO4) salt chambers until the
reading is correct.
5.3 Calibration with HMI41 software commands
Calibration can also be done with the HMI41 software commands by entering
the corrections in the indicator memory with pushbuttons. If only one probe is
being used, the HMI41 software calibration is useful. However, when several
probes are in use, it is recommended that calibration is done by adjusting the
probe potentiometers. Note that when the sensor head set is changed,
calibration must always be done by adjusting the potentiometers and it is
recommended that the HMI41 is reverted to factory settings by selecting
default calibration.
NOTE
If the factory calibration of the HMI41 is changed, the
correction data refers to the calibrated probe only.
Therefore, if you change the probe, always revert this
data to factory settings by selecting default calibration,
or perform a new calibration with the new probe.
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HMI41 AND HMP42
U323en-1.1 Operating Manual
The calibration procedure is included in the HMI41 setup mode. For entering
the setup mode, first press the ON/OFF button and the following appears:
RH
Td
T
P
set min max hyst hold Lo bat Hi
%
°C °F
°C
°F
Pahg/m
Then release the ON/OFF button and press within 1...2 seconds 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:
°C
set
Press ENTER eight times until the following text appears:
set
This indicates that no calibration has been selected. In addition to this, there
are five calibration types available. The desired type is selected with buttons
▲ or ▼.
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HMI41 AND HMP42
Operating Manual U323en-1.1
All selections are acknowledged with ENTER. In the following, you will find
a list of these calibration options.
RH
T
Default calibration restores the factory settings of
the humidity and temperature calibrations.
set
RH
One point humidity calibration; select this for
performing humidity calibration at one point. See
Chapter 5.3.1 for further details.
set
RH
Two point humidity calibration; select this for
performing humidity calibration at two points.
See Chapter 5.3.2 for further details.
set
T
One point temperature calibration; select this for
performing temperature calibration at one point.
See Chapter 5.3.3 for further details.
set
T
Two point temperature calibration; select this for
performing temperature calibration at two points.
See Chapter 5.3.4 for further details.
set
16
5.3.1 One point humidity calibration
In one point humidity calibration, one accurate humidity reference is
sufficient. However, note that after one point calibration, the humidity reading
is most accurate near the reference value. For a better accuracy over the whole
range, perform a two point calibration if possible.
Leave the reference instrument (HMK15 or HMK13B) and the probe at the
calibration site at least 30 minutes so that the probe temperature stabilizes to
the room temperature. Start the calibration by inserting the probe to the
reference humidity.
In setup mode, press ENTER repeatedly until the following is displayed:
set
HMI41 AND HMP42
U323en-1.1 Operating Manual
Then press MODE twice, and the following appears:
RH
set
Press ENTER to activate the one point calibration mode. A message similar to
the following appears with the first line blinking:
RH
set
%
The blinking number indicates the humidity reference value in the HMI41
memory. Check the salt chamber temperature, read the closest humidity value
in the calibration table and adjust the display with buttons ▲ and ▼ to
correspond to the value given in the table. For example, if the temperature in
the calibrator's NaCl salt chamber is 20.5 °C, adjust the value to 75.5 %RH:
RH
set
%
Each time the button is pressed, the value changes with 0.1 %. If you keep the
button pressed, the value changes in a faster mode. Press ENTER and the
HMI41 indicator shows the value that the probe is currently measuring,
displaying a message similar to the following:
RH %
Wait at least ten minutes for the reading to stabilize and press ENTER to
acknowledge the value. Press ENTER again to conclude the one point
calibration. If the calibration has been successful, the following message
appears:
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Operating Manual U323en-1.1
The correction data has now been calculated and stored in the HMI41 memory.
The HMI41 returns automatically to the selection of display units, and can be
turned off. When the indicator is used as a standard indicator and the
correction data differs from the factory settings, an arrow in the upper
righthand corner is displayed:
RH
T
%
°C
If the message “cal pass” does not appear (instead, some other text may
appear, e.g. “too close”, “err offst” or “err gain”), the correction has not been
stored in the memory. The error may be due to an incorrect reference value or
to measured values that are out of the range.
5.3.2 Two point humidity calibration
In two point humidity calibration, two accurate references (e.g. the HMK15 or
the HMK13B Calibrator) are needed. Leave the reference instrument and the
probe at the calibration site for at least 30 minutes so that the probe
temperature stabilizes to the room temperature.
Start the calibration by inserting the probe to the lower reference humidity. In
setup mode press ENTER repeatedly until the following is displayed:
18
set
Then press MODE three times, and the following appears:
RH
set
Press ENTER to activate the two point humidity calibration mode. A message
similar to the following appears with the first line blinking:
RH
set
%
Lo
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