Functional Checking With Test Filters - Honeywell Searchline Excel Cross-Duct Technical Handbook

MAN0889_Issue 3_03/13
To get the best accuracy when using the gassing cell:
(1) Ensure that the gassing cell contains fresh air, and perform a zero calibration on the Excel
(2) Apply the test gas and allow sufficient time to fully fill the gassing cell and check that the Searchline Excel
Cross-Duct output stabilises.
A flow rate of less than 0.5 litres per minute is advisable, to avoid pressurising the gassing cell.
(3) For a methane calibrated unit tested with 100%v/v methane (UL version) or 88%v/v methane (ATEX, IECEx
version), the expected reading can be calculated from:
A few examples are shown in the following table, and the tolerance to be applied is ± 20% of reading or
± 10%LEL (whichever is greater). The variability in the readings is due to a number of factors such as variation in air
pressure, flow rate, and tolerances in the gas composition.
Test Gas
UL version
100% v/v Methane
100% v/v Methane
100% v/v Methane
100% v/v Methane
100% v/v Methane
100% v/v Methane
(4) After checking the reading, ensure that the gas is flushed out of the gassing cell, with clean air or nitrogen,
until the reading returns to zero.
(5) Finally replace the rubber caps over the gassing ports.
Tests gases may be flammable and/or toxic. Take appropriate precautions
Take the necessary precautions to ensure safety when dealing with high

4.3.2 Functional Checking with Test Filters

Functional checking of the Searchline Excel Cross-Duct can also be done using plastic test filters (part number
2104N3000). Plastic test filters inserted in the measuring path produce infrared absorption which approximates
that of methane gas. For the procedure see section 3.6.6.
Compare the gas reading to the original value recorded for this unit when tested with this filter. Provided that
the reading is within ±15% LEL of the original value, the unit is working correctly.
If the gas reading is not within the expected range it is possible that the unit needs cleaning or re-zeroing.
See section 4.1.
4. Maintenance
Gas reading = 100%LEL / (2 x duct width)
Test Gas
ATEX, IECEx version
88%v/v Methane
88%v/v Methane
88%v/v Methane
88%v/v Methane
88%v/v Methane
88%v/v Methane
WARNING:
when handling
WARNING:
concentration gases
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Searchline Excel Cross-Duct Technical Handbook
Duct Width
0.5m
100%LEL ± 20%LEL
0.8m
1.0m
1.5m
2.0m
2.5m
20% LEL ± 10%LEL
Expected Reading
60%LEL ± 12%LEL
50%LEL ± 10%LEL
33%LEL ± 10%LEL
25%LEL ± 10%LEL