Rae QRAE PLUS PGM-2000, Operation & Maintenance Manual

Page: 45 / 88

PROGRAMMING
4-7
Diffusion Instruments
QRAE PLUS diffusion monitors must be calibrated using a fixed
flow regulator with a flow rate between 0.5 and 1.0 liters per
minute. Diffusion monitors are supplied with a special
calibration adapter that covers the gas diffusion port.
Sensor Calibration Time
Slowly responding sensors listed in the table below may require
pre-exposure of the sensor to the gas immediately before
initiating the calibration sequence. Some firmware versions use
a fixed 60-second calibration time; some newer versions
automatically apply the full calibration time. After completing the
zero calibration, expose the unit to the gas for the pre-exposure
time listed below if a 60-second countdown time is
programmed in the unit.
If the firmware has the full calibration time programmed in, the
sensors must be calibrated in the Single Sensor mode to take
advantage of this feature. The calibration time is set at 60
seconds in the Multiple Sensor mode and may not be changed.
Sensor
Response
Time t
90
(seconds)
Total
Cal Time
(seconds)
Pre-exposure
Time for 1-min
Cal Time
HCN 200 230 170
ClO2, NH3,
COCl2
150 150 90
Cl2, PH3 60 120 60
CO, H2S,
SO2, NO,
NO2, O2,
LEL, VOL
=40 60 0