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Manual
MS-00809-0100-3625
3
Operation
During operation, there is very little to do with the detector other than performing regular
function tests and cleaning the lens and mirror if they are dirty.
3.1
Function test
To perform a function test, apply gas using one of the gas test kits. This is a simple test
carried out to make sure the detector will respond when exposed to gas and is often
referred to as bump testing.
Perform this test on a regular basis to verify the safety functions of the detector. Use this
test to confirm that the detector is responding to gas presence and generating the correct
outputs as prescribed. The operator can select from one of the methods, depending on the
configuration of the detector and local preferences.
Test interval
The time between two periodical tests of the detector's safety functions is from a safety
context called the test interval. The Rosemount 625IR is certified in accordance with the
standard IEC 61508 with Safety Integrity Level 2 (SIL2) rating. If used in a one out of two
(1oo2) configuration, the detector is rated for SIL3.
NOTICE
Gas being released from a gas cylinder will give a very small gas cloud, which dilutes very
quickly. This is challenging when testing a gas detector, since the gas reaching the gas
detector will have a much lower concentration compared to what is stated on the gas
cylinder. Especially if there are windy conditions, it can be challenging to get any gas to the
detector with a small amount coming from a gas cylinder. For example, if you use a 50
percent lower explosive limit (LEL) test gas and inject it at 2 liters/minute into a 625IR fitted
with an environment shield using the gas test kit, this can result in a gas reading as low as
20 percent LEL in windy conditions.
Take precautions when testing a detector to get valid results.
Related information
Verify detector accuracy
Rosemount 625IR
Operation
January 2024
27
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