OPERATION OF ACCESSORIES
3-8
3.5 Dilution Fitting
An optional dilution fitting can be installed with the remote
sampling probe or Teflon
®
tubing on the gas inlet port to dilute
gas samples. This fitting is needed when the gas sample
contains less than 15% oxygen. The combustible sensor does
not function correctly when the oxygen concentration falls
below 15%. The dilution fitting increases the oxygen
concentration so the combustible sensor may still be used
under oxygen deficient conditions. The dilution fitting may also
be used to measure combustible, VOC or toxic gases when
concentrations exceed the upper limit of the sensor range.
To use the dilution fitting, insert the fitting between the External
Filter and the remote sampling probe or Tygon tubing. Set the
dilution ratio in Program Mode so the correct gas reading
displays when the dilution fitting is used. (See Section 4.8.4:
Change Dilution Ratio.)
WARNING
For this application, the monitor must be located in a clean
atmosphere outside the confined space and a remote access
probe or Teflon
®
tubing used to measure the gas concentration.
3.6 Calibration Adapter
The AreaRAE should be calibrated with the external filter in
place. The AreaRAE calibration adapter is designed to slip over
the filter. During calibration, connect the calibration adapter to
the cylinder of the calibration gas. Then insert adapter into the
filter and allow the gas to flow to sensors.
NOTE:
The gamma radiation sensor in the AreaRAE Gamma
and AreaRAE Gamma Steel is factory calibrated with a fixed
gamma radiation source. There is no need to calibrate the
gamma sensor in the field.