Adjusting and calibrating relative humidity after sensor change - HMP155

HMP155 User Guide
Document code
M210912EN
Revision
G.1
Language
English
Product
HMP155
Document type
User guide
After sensor change, you must calibrate and adjust the relative humidity.
  1. Connect HMP155 to a computer.
  2. Open a terminal program.
  3. Carry out chemical purge, if available.
  4. Press the ADJ button. The green LED lights up.
  5. Remove the filter from the probe and insert the probe into a measurement hole of the dry end reference chamber (for example, LiCl: 11 % RH).
  6. Type the FCRH command and press ENTER.
    When you type the fcrh command, the RH readings are indicative. They enable you to check the stability of the readings. The readings are based on the parameters of the old relative humidity sensor. In some extreme cases, the RH reading can be negative or extremely high. After the adjustment, the actual RH readings are correct.
  7. Wait at least 30 minutes for the sensor to stabilize.
  8. Press ENTER a few times to check if the reading has stabilized.
  9. When the reading has stabilized, give the reference humidity after the question mark and press ENTER. 
    >fcrh
RH : 25.19 Ref1 ? 11.3
Press any key when ready ...
RH : 70.02 Ref2 ? 75.5
OK
>

    The device is waiting for the high end reference.

  10. Insert the probe into the measurement hole of the high end reference chamber (for example, NaCl: 75 % RH chamber in the humidity calibrator HMK15) and press any key.
  11. Let the probe stabilize for about 30 minutes. You can follow the stabilization by pressing ENTER.
  12. When stabilized, type the high end reference value after the question mark and press ENTER. 
    RH  :    75.45  Ref2 ?
RH  :    75.57  Ref2 ?
RH  :    75.55  Ref2 ?
RH  :    75.59  Ref2 ? 75.5
OK

    OK indicates that the adjustment has succeeded and the new calibration coefficients are calculated and stored.

  13. Type the calibration information, date and text, to the memory of the probe.