Honeywell SEARCHLINE EXCEL PLUS - Calibration Check Using the Gassing Cell

60 Chapter 9 Maintenance
Searchline Excel™ Plus / Searchline Excel™ Edge – Technical Manual
9.4Calibration Check using the Gassing Cell
CAUTION
!
Prerequisite for calibration check using the gassing test cell is installation of the Honeywell Fixed Platform App
to the handheld device.
The gassing test cell allows calibration to be checked using a user-specified gas concentration, as an alternative to
the standard functional test filters.
The integrated LEL.m reading of the gas concentration in the test cell can be calculated using the following formula:
Int(LEL.m)
xl
= L
cell
* (Conc
gas
/ LEL
gas
)
where:
Int(LEL.m)
xl
= Integrated LEL.m reading output by Searchline Excel Plus & Searchline Excel Edge in LEL.m
L
cell
= Length of test cell in metres
Conc
gas
= Gas concentration in %v/v
LEL
gas
= Lower Explosive Limit of the gas in %v/v
The test gas must be the same as the test gas used during the initial calibration of the Searchline Excel Plus &
Searchline Excel Edge units and ideally the concentration should be between 2 and 5 LEL.m, never below 1 LEL.m.
Note
Cross-calibration is not recommended. Typical values for cross-sensitivity are not sufficiently precise to enable valid
calibration checks using the gassing test cell.
Response tests can easily be performed with the functional test filters as described in Chapter 9.2.
WARNING
!
Take necessary precaution to ensure safety when dealing with high concentration gasses.
The gassing test cell supplied by Honeywell Analytics (Part No: 2017B0185) is 17 cm (0.55 ft) long and the following table
outlines the response expected when using this gassing test cell:
Gas type LEL of the gas Concentration
applied
Calculated
response with
17 cm gas test cell
420mA output
Methane 4.4 % v/v 65 %v/v 2.5 LEL.m 12.0 mA
Ethane 2.4 % v/v 35 %v/v 2.5 LEL.m 12.0 mA
Propane 1.7 % v/v 25 %v/v 2.5 LEL.m 12.0 mA
Butane 1.4 % v/v 20 %v/v 2.5 LEL.m 12.0 mA
Pentane 1.1 % v/v 16 %v/v 2.5 LEL.m 12.0 mA
Ethylene 2.3 % v/v 34 % v/v 2.5 LEL.m 12.0 mA
Propylene 2.0 % v/v 30 % v/v 2.5 LEL.m 12.0 mA
WARNING
!
These gases are flammable and/or toxic. Take appropriate precautions when handling.