Calibration Check Using The Gassing Cell - Honeywell Searchline Excel Technical Handbook

MAN0530 Issue 10 - 11/09
2104M0506
14) Remove the test filter from the cowling.
15) Release the unit under test from INHIBIT by selecting the MAIN menu option.
16) Disconnect the SHC-1 Handheld from the unit being tested.

4.3 CALIBRATION CHECK USING THE GASSING CELL

The gassing cell is designed to allow easy calibration checking using a high concentration test
gas as opposed to the standard plastic test filters. The integrated LEL.m reading of the gas
concentration in the cell can be calculated using the following formula:
where:
Int(lel.m) = Integrated LEL.m reading output by Searchline Excel in LEL.m.
xl
L = Length of cell in metres.
cell
Conc = Gas concentration in %v/v.
gas
LEL = Lower Explosion Limit of the gas in %v/v.
gas
The test gas must be the same as the test gas used during the factory calibration of the
Searchline Excel unit and ideally the concentration should be between 2 and 5 LEL.m and
never below 1 LEL.m.
Note: Where a different test gas is used, the typical value for cross-sensitivity is not sufficiently
precise to enable valid calibration checks to be performed using the Gassing Cell,
however, response tests can be easily performed with the plastic Test Filters as described
in section 5.1.2.
Take the necessary precaution to ensure safety when dealing with these
The gassing cell supplied by Honeywell Analytics (Part No: 2104B2326) is 0.15m long and the
following table outlines the response expected when using this gassing cell:
Gas type
Methane
Ethane
Propane
Butane
4. MAINTENANCE
Int(lel.m) = L
xl
WARNING
high concentration gasses.
LEL Concentration
of the gas applied
5.0 %v/v 100 %v/v
3.0 %v/v 50 %v/v
2.0 %v/v 50 %v/v
1.5 %v/v 50 %v/v
*
(Conc / LEL
cell gas
Calculated
response with
0.15m gas cell.
3 LEL.m
2.5 LEL.m
3.75 LEL.m
5 LEL.m
57
Searchline Excel
)
gas
4-20mA output
13.6mA
12mA
16mA
20mA