35-3010A-11 Sample-Draw Detector • 23
Calibration, LEL Detector
This section describes how to calibrate the LEL sensor in the sample draw detector. It
includes procedures to set the zero reading, set the response reading, and return to normal
operation.
NOTE:
This procedure describes calibration using a demand flow regulator, a zero air
calibration cylinder, and a 4-gas calibration cylinder.
Setting the Zero Reading
NOTE:
If you can verify a fresh air environment, it is not necessary to use the zero air
calibration cylinder to set the zero reading.
1.
Open the housing door.
2.
Screw the regulator into the zero air calibration cylinder.
3.
Connect the calibration kit sample tubing to the regulator.
4.
The zero reading for the LEL channel is set at the controller. See the controller
operator’s manual for instructions to set the zero reading.
5.
When the instructions call for applying gas to the detector, connect the sample tubing
from the regulator to the inlet line at or near the INLET fitting.
6.
Allow the gas to flow for 1 minute.
7.
Set the zero reading according to the controller operator’s manual.
8.
Disconnect the sample tubing from the inlet line.
9.
Unscrew the regulator from the zero air calibration cylinder. Leave the sample tubing
connected to the regulator.
Setting the Response Reading
1.
Screw the regulator into the 4-gas calibration cylinder.
2.
Connect the sample tubing to the regulator.
3.
Follow the directions in the controller’s operator’s manual for setting the response
reading for the LEL channel.
4.
When the instructions call for applying gas to the detector, connect the sample tubing
from the regulator to the inlet line at or near the INLET fitting.
5.
Allow the calibration gas to flow for 1 minute.
6.
Set the response reading according to the controller operator’s manual to match the
calibration gas concentration.
7.
Disconnect the sample tubing from the inlet line.
8.
Unscrew the regulator from the calibration cylinder.
NOTE:
For convenience, leave the regulator connected to the sample tubing.
