User manual

OPERATING INSTRUCTION
Technical changes reserved
0141 0315-199 09/2014
Humidity reference cells
for adjustment of humidity sensors
CAUTION! The cleaning with distilled water is permitted only for sensors. Resistive or electrolytic humidity sensors get seriously damaged
beyond repair through water contact and needs to be replaced! Humidity sensors of other manufacturers are normally not water resistant
and can get damaged through water contact. If necessary, obtain clarication from the manufacturer about cleaning instructions of the
sensing unit.
The guidance for adjustment of the devices are available in the appendix section of the respective operating instructions of the device. The
relevant documentation can be obtained from us on request.
For hygrometers of other companies, please contact the respective manufacturer.
It is not necessary to adjust the device during the calibration process. It is often sufcient to record the deviation and take into account
during future measurements.
The checking or adjustment should be carried out only after the system is stabilised, which means that all components (salt solution, atmos-
phere in adjustment chamber, and sensing unit which is to be adjusted) can be considered at the same temperature and humidity conditions.
In practice, an accuracy of up to 2 % (without adjustment) can be obtained for simple testing purposes, with a stabilisation time of at least 30
minutes. For adjustment or quality intensive calibrations, stabilisation time of at least 4 hours is required.
Stabilisation must be carried out in temperature stable environment. This can be done by keeping in a polystyrene box.
During stabilisation time, the cell or the sensing unit should not be touched. While assembling cells on sensors, unnecessary contact with the
hands should be avoided.
The following items are required: At least two reference cells, a polystyrene container, adjustment instructions of the device, a calibrated
thermometer, these guidelines with the salt tables and a measuring instrument. If a transducer without display have to be calibrated a
display unit is additionally needed.
Either replace the battery of the device or connect it to power supply during adjustment. First check the device for error free functioning.
Only reasonable measurements must be displayed. Defective devices must be rst repaired before adjustment.
Take the device into operation so that measured values can be observed. Use an display unit or a calibrated current/voltage measuring
instrument for transducers.
Then carefully remove the protection cap of the sensing unit. CAUTION! Remove the protection cap and then axial take out without tilting!
The sensor is unprotected and hence, it is very susceptible to damage.
After that, check the condition of the sensor elements. Damaged or scratched sensors should be replaced. Contaminated sensing elements
should be rst cleaned and then dried.
Please follow the security tips about the reference cells. Unscrew the caps of salt-reference-cells and
check the inside area. Carefully wipe out the liquid outow with a lint free cloth. Check the level and saturation status of the salt solution in the
reference cell. Defective reference cells must be separated out!
Carefully mount the sensing unit on the adjustment adapter. Use an appropriate adaptor with suitable threads which can hermetically seal the
assembly. Avoid unnecessary palm contact to the cell and sensor to rule out unwanted thermal instability. Place the sensing unit with the cell
in the carry-case or in a closed polystyrene container for stabilisation. No further heat sources should be present in the polystyrene container.
4.10 Guidance for adjustment
4.11 Stabilisation time
5. Checking and adjustment procedure
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B+B Thermo-Technik GmbH | Heinrich-Hertz-Straße 4 | D-78166 Donaueschingen
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