Vaisala HMP46 User Manual

USER'S GUIDE

Vaisala HUMICAP® Indicator HMI41

and Probes HMP41/45/46

M210316EN-A

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/

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 AND PROBES

M210316EN-A 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 probes ........................................................................................... 4

4. TAKING MEASUREMENTS ................................................................................................. 5

4.2 Starting the measurements ....................................................................................5

4.2 Measurement readings on display ......................................................................... 6

4.3 HOLD-mode.............................................................................................................7

5. CALIBRATION.....................................................................................................................8

5.1 Calibration with trimmer potentiometers...............................................................8

5.2 Calibration with HMI41 software commands ....................................................... 10

6. HMI41 AND DATA COLLECTING ...................................................................................... 20

6.1 Entering the data collecting mode....................................................................... 20

6.2 Manual data collecting..........................................................................................21

6.3 Setting the measurement duration ....................................................................... 22

6.4 Setting the measurement interval ........................................................................ 22

6.5 Reading the measurement results ....................................................................... 23

7. TRANSFERRING THE STORED READINGS TO A PC...................................................... 26

7.1 Giving the communication parameters................................................................26

7.2 Transferring the data ............................................................................................ 29

8. CHANGING THE SETTINGS .............................................................................................. 33

8.1 Entering the setup mode ...................................................................................... 33

8.2 Selecting the display units................................................................................... 34

8.3 Setting the automatic power-off function............................................................ 34

8.4 Selecting the display quantities........................................................................... 35

8.5 Setting the pressure for mixing rat io and w et bu lb temperat ure calculatio ns . 35

8.6 Selecting the probe type....................................................................................... 36

9. MAINTENANCE ................................................................................................................. 37

9.1 Changing the HUMICAP

9.2 Chemical tolerances of the HUMICAP



180 humidity sensor..................................................... 37



180 sensor.............................................. 37

9.3 Using the HMP46 in high temperatures ............................................................... 37

9.4 Spare parts and accessories................................................................................ 38

HMI41 AND PROBES Operating Manual M210316EN-A

10. IN CASE OF ERROR..........................................................................................................39

10.1 Trouble shooting ...................................................................................................39

10.2 Checking the settings ........................................................................................... 40

11. TECHNICAL DATA.............................................................................................................41

11.1 HMI41 indicator......................................................................................................41

11.2 HMP41and HMP45 probes.....................................................................................42

11.3 HMP46 probe.......................................................................................................... 43

11.4 Accuracy of the calculated quantities..................................................................44

11.5 Electromagnetic compatibility..............................................................................47

APPENDIX 1 QUICK REFERENCE GUIDE................................................................................48

WARRANTY............................................................................................................................... 65

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M210316EN-A 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.

There are six different probe types that can be used with the HMI41 indicator. 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/L 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

various applications, for example in spot checks.

• HMP42 probe head has a diameter of only 4 mm and is 23.5 cm long.

This probe structure is specially indicated for measurements in very tight places, e.g. in joint spaces between tiles or in air conditioning channels as well as for measuring the equilibrium humidity of e.g. timber (separate manual).

• HMP44 and HMP44L are used for measuring humidity in concrete

and other structures (separate manual).

• 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 consists of a 32 cm long probe head of stainless steel; the

HMP46 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.

HMI41 AND PROBES Operating Manual M210316EN-A

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 also be frozen to show the current readings, and it can be used for checking the minim um 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). If required, the collected data can be transferred to a PC; an optional serial interface cable is available for this purpose (order code 19446ZZ).

The humidity measurement range is 0...100 %RH. The temperature measurement range depends on the probe used. Relative humidity is measured with the accurate and stable HUMICAP180 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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M210316EN-A 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.

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

HMI41 AND PROBES Operating Manual M210316EN-A

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 probes

After having inserted the batteries, connect the probe you wish to use. The HMP41 is connected to the connector on top of the HMI41: remove the plastic plug and mount the probe (see Figure 3.2). The HMP45 and the HMP46 both have a cable to be plugged into the connector at the bottom of the HMI41, marked PROBE (see Figure 3.2). The other connector is for calibration cables.

HMP45 and HMP46 cable

Figure 3.2 Connecting the probes to the HMI41

HMP41

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4. TAKING MEASUREMENTS

4.2 Starting the measurements

Before starting the measurements with the HMI41 and appropriate probe, remember to allow enough time for stabilization.

Turn the power on with the ON/OFF button and the following appears:

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 then the probe type indication (41.45 or 42.46):

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 HMP46 probe. If the probe type does not appear, the indicator or the probe is of a previous version and the automatic recognition is not possible; give the 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):

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

HMI41 AND PROBES Operating Manual M210316EN-A

4.65 V, the indicator turns itself off to prevent erroneous measurements and readings. Should this happen, replace the batteries.

4.2 Measurement readings on display

Relative humidity and temperature readings appear automatically after the battery charge indication:

°C

If MODE is pressed, dewpoint temperature (Td) reading is displayed:

Td T

°C °C

When MODE is pressed again, one of the following is displayed or the HMI41 returns to showing the RH and T readings according to what has been chosen for the measurement quantities (see Chapter 8.4):

°C

abs

g/m

Temperature and absolute humidity

°C °C

Temperature and wet bulb temperatu re; the

arrow in the lower righthand corner indicates that wet bulb temperature has been chosen

°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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M210316EN-A Operating Manual

4.3 HOLD-mode

In any of the previously mentioned measurement reading displays, the button HOLD freezes the display to show the current readings, e.g. RH & T readings:

°C

hold

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

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):

min

°C

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 power up, press HOLD when the indicator is in the MIN-mode. The maximum readings of the currently displayed quantities appear:

max

°C

The indicator returns to the normal display mode with any button except ON/OFF.

HMI41 AND PROBES Operating Manual M210316EN-A

5. CALIBRATION

The HMI41 indicator and probes are fully calibrated at the factory, so there should be no immediate need for recalibration. Calibration is recommended once in a year and always when there is a reason to believe that the adjustments have changed.

5.1 Calibration with trimmer potentiometers

5.1.1 Humidity calibration

Humidity calibration of the probes is preferably done by adjusting the 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 5.1.1).

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.

HMP41 &

HMP46

wet

dry

W D

HMP45

TWD

wetdry

Figure 5.1.1 Location of trimmer potentiometers

A two point calibration is performed with the HMK15 calibrator or the probe can be sent to Vaisala. The probes must always be recalibrated when the sensor is changed.

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M210316EN-A 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. Unscrew the plastic grid (HMP41 and HMP45) or the sintered filter (HMP46) of the probe.

• Insert the probe into a measurement hole of the LiCl salt chamber in

the humidity 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

5.1.1).

• 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.

Table 5.1 Greenspan’s calibration table

°C 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

LiCl NaCl K2SO

HMI41 AND PROBES Operating Manual M210316EN-A

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.

5.2 Calibration with HMI41 software commands

Calibration can also be done with the HMI41 software commands. When

calibration is done with software commands, the corrections are entered 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, calibration should be done by adjusting the probe potentiometers. Note that when the sensor 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.

The calibration procedure is included in the HMI41 setup mode. Enter the setup mode by pressing the ON/OFF button. The following appears:

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

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M210316EN-A Operating Manual

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 ▼. All selections are acknowledged with ENTER. In the following, you will find a list of these calibration options.

Default calibration restores the factory settings of the humidity and temperature calibrations.

set

One point humidity calibration; select this for performing humidity calibration at one point. See Chapter 5.2.1 for further details.

set

Two point humidity calibration; select this for performing humidity calibration at two points. See Chapter 5.2.2 for further details.

set

One point temperature calibration; select this for

performing temperature calibration at one point. See Chapter 5.2.3 for further details.

set

Two point temperature calibration; select this for

performing temperature calibration at two points. See Chapter 5.2.4 for further details.

set

5.2.1 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) 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.

HMI41 AND PROBES Operating Manual M210316EN-A

In setup mode, press ENTER repeatedly until the following is displayed:

set

Then press MODE twice, and the following appears:

set

Press ENTER to activate the one point calibration mode. A message similar to the following appears with the first line blinking:

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:

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

HMI41 AND PROBES

M210316EN-A Operating Manual

calibration. If the calibration has been successful, the following message appears:

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:

°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.

5.2.2 Two point humidity calibration

In two point humidity calibration, two accurate references (e.g. the HMK15 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:

set

Then press MODE three times, and the following appears:

set

HMI41 AND PROBES Operating Manual M210316EN-A

Press ENTER to activate the two point humidity calibration mode. A message similar to the following appears with the first line blinking:

set

The blinking number indicates the value of the lower humidity reference stored 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 of the LiCl salt chamber is 22 °C, adjust the value to

11.3 %RH:

set

Press ENTER, and the HMI41 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 lower point calibration. A message similar to the following appears with the first line blinking:

set

The blinking number indicates the value of the higher humidity reference stored in the HMI41 memory. Insert the probe to the higher reference humidity. 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:

HMI41 AND PROBES

M210316EN-A Operating Manual

set

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 calibration. If the calibration has been successful, the following message appears:

The correction data has now been calculated and stored in the HMI41 memory. The HMI41 returns automatically to the selection of the 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:

°C

5.2.3 One point temperature calibration

In one point temperature calibration, one accurate temperature reference is sufficient.

Start the calibration by inserting the probe to the reference temperature. In setup mode, press ENTER repeatedly until the following is displayed:

HMI41 AND PROBES Operating Manual M210316EN-A

set

Then press MODE four times, and the following appears:

set

Press ENTER to activate the one point temperature calibration mode. A message similar to the following appears with the first line blinking:

T°C

set

The blinking number indicates the temperature reference value stored in the HMI41 memory. Check the actual temperature reference and change the display with buttons ▲ and ▼ to correspond to the accurate value, for example:

T°C

set

Press ENTER and the HMI41 indicator shows the value that the probe is currently measuring, displaying a message similar to the following:

T°C

Wait at least ten minutes for the reading to stabilize and press ENTER to acknowledge the value. Press ENTER again to conclude the calibration. If the calibration has been succesful, the following message appears:

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M210316EN-A Operating Manual

°C

5.2.4 Two point temperature calibration

In two point temperature calibration, two accurate temperature references are needed. Note that you must allow enough time for all instruments to stabilize to the temperature equilibrium.

Start the calibration by inserting the probe to the lower reference temperature. In setup mode, press ENTER repeatedly until the following is displayed:

set

Then press MODE five times, and the following appears:

set

Press ENTER to activate the two point temperature calibration mode. A message similar to the following appears with the first line blinking:

HMI41 AND PROBES Operating Manual M210316EN-A

set

°C

The blinking number indicates the value of the lower temperature reference stored in the HMI41 memory. Insert the probe to the lower reference temperature. Check the reference temperature and change the display with buttons ▲ and ▼ to correspond to the accurate value, for example:

set

°C

Press ENTER and the HMI41 shows the value that the probe is currently measuring, displaying a message similar to the following:

°C

set

°C

The blinking number indicates the value of the higher temperature reference stored in the HMI41 memory. Insert the probe to the higher reference temperature. Check the reference temperature and change the display with buttons ▲ and ▼ to correspond to the accurate value, for example:

°C

set

Press ENTER and the HMI41 shows the value that the probe is currently measuring, displaying a message similar to the following:

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