FRM 2025 Temp & BP Check & Calibration

 

Purpose:  Follow the steps below to perform FRM 2025 temperature and barometric checks.

 

Required Equipment:  Psychrometer

 

Reference:  R&P FRM 2025 service manual pages 3-12 & 3-16.

 

1.        Open the FRM front door.  Press F2 button labeled STATS two times.  Record the ambient temperature and barometric pressure from FRM 2025 display into site log.

2.        Record ambient barometric pressure from the Site Manager BP channel and temperature from the psychrometer into site log. 

3.        Tolerance for the temperature check is +/-1 degree.

4.        Tolerance for the barometric check is +/- 3 mbar.

5.        Refer below or to R&P service operating manual page 3-16 for barometric pressure and page 3-12 for temperature calibration if check fails to meet tolerance.

 

Ambient Air Temperature Calibration

 

  1. Press <MENU> to enter the Service Menu.  With the cursor point- pointing to “Calibration/Audit,” press <F3: SensCal> to enter the Sensor Calibration Screen.
  2. If the calibration will be done at ambient conditions, the reference temperature measurement can be taken with the probe installed in the radiation sensor.
  3. If the calibration is done at a temperature lower and/or higher than ambient temperature, loosen the two screws on either side of the temperature probe on the ambient temperature assembly and remove the probe from the radiation shield.  The reference and sampler probe should be banded together and immersed to the same depth in an insulated constant temperature bath or block.  Reference and sampler probes should be equilibrated at temperature for at least 5 minutes before the temperature is measured.
  4. Press <Edit> then enter the measured reference temperature in °C [°C = 5/9 x (°F - 32)] in the Actual column of the Amb Temp row of the Sensor Calibration Screen, press <Enter>. The sampler automatically adjusts the corresponding offset based upon this input.
  5. If removed, reinstall the ambient temperature probe in the radiation shield, and tighten the two screws on either side of the probe.

 

Ambient Pressure Calibration

 

  1. Press <MENU> to enter the Service Menu.  With the cursor pointing to “Calibration/Audit,” press <F3: SensCal> to enter the Sensor Calibration Screen.
  2. Determine the current ambient station pressure in mm Hg (absolute pressure, not corrected to sea level).

• To convert from Atmospheres @ 0 °C to mm Hg, multiply by 760.

• To convert from millibar to mm Hg, multiply by 0.75012.

• To convert from inches Hg @ 32 °F to mm Hg, multiply by 25.4.

  1. Press <Edit> and enter the measured ambient pressure in the Actual column of the Amb Pres row of the Sensor Calibration Screen and press <Enter>.  The sampler automatically adjusts the corresponding offset based upon this input.