Two-point humidity adjustment - HMP155

HMP155 User Guide

Document code
M210912EN
Revision
G.1
Language
English
Product
HMP155
Document type
User guide
The difference between the 2 humidity references must be at least 30 %RH.
In the active output version of HMP155, you can calibrate and adjust both the temperature (T) and additional T-probe temperature (Ta).
  1. Connect HMP155 to a PC.
  2. Open a terminal program.
  3. Carry out the chemical purge, if available.
    1. To set purge on, type PUR.
    2. To reset the probe, type RESET.

      Wait for 8 minutes before taking measurements.

  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 CRH command and press ENTER.
  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, type the reference humidity after the question mark and press ENTER.
    >crh
    RH  :  16.6675 1. ref ?
    RH  :  16.4978 1. ref ?
    RH  :  16.3956 1. ref ? 11.25
     Press any key when ready ...
     RH  :    11.25  Ref2 ?
    

    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). Press any key when ready.
  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.
  14. Reset the probe with the RESET command.
  15. Take the probe out of the reference conditions and replace the filter, if needed.​