Section 2 Detective+
modules. It also applies the corrected gas values to the log file. The exact list
of gases and their corrections is configurable via a PC and the Portable PC soft-
ware. The default of gas correction factors for flammable gases with respect to
methane and pentane are listed in Appendix 2.
CALIB
This allows re-calibration of the instrument, which must first have been Zeroed
in clean air. You will need a calibration flow plate, which is included as stand-
ard with the Detective+ and a supply of Crowcon calibration gas (see section
VIII Maintenance and Calibration). The top line now displays one of the instru-
ment’s gas channels. This display will look like:
Use the first two keys to select the required gas. Press QUIT to move back up a
menu level, or CAL to select the gas to calibrate. The display will now change to:
The actual gas reading is displayed on the top line, and should go up when the
relevant TEST GAS is aspirated over the sensors. When the reading has stabi-
lised use the UP and DOWN keys to make the reading match the known test
gas concentration. Now press CAL to actually calibrate the instrument’s gain.
QUIT can be pressed to abandon the calibration. If the instrument is calibrated,
it will either respond with CAL SUCCESSFUL or CAL FAILED. If the calibration
failed the instrument’s gain is not changed, and means that either the gas con-
centration was not equal to the value set (check both and repeat) or that the
sensor has deteriorated with use (see Maintenance and Calibration for sensor
replacement).
When a calibration is being performed, replace the integral flow plate with the
calibration flow plate so the gas is not being sampled by the pump.
Note: when calibrating flammable sensors they will always appear in the CALIB
menu as the sensor type they really are without any flammable correction factor
applied. They should also be calibrated as per the gas they really are, and not
Configuration options Detective+
<< >> QUIT CAL
CALIBRATE: CH4 (Chan.1)
UP DOWN QUIT CAL
CALIBRATE: CH4 = 0
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