Bump test can also be referred to as function test. Bump test is used to verify that the gas detector is working accordingly; ensuring that the gas sensor is responding to the target gas. Sensors and alarm indicators are tested, ensuring acceptable performance of sensors and monitor before use.
Exposing the gas detector to a known concentration of test gas will show if the sensor respond accurately and if the instrument alarm is working properly.
It is recommended that this test be carried out daily before use.
OSHA has this to say about Bump Test:
“This is a qualitative function check in which a challenge gas is passed over the sensor(s) at a concentration and exposure time sufficient to activate all alarm settings. The purpose of this check is to confirm that gas can get to the sensor(s) and that all the instrument’s alarms are functional. When performing a bump test, the challenge gas concentration should trigger the DRPGM’s alarm(s).”
Why should i carry out bump test
When we think about why we should carry out bump test, we should take our minds back to why we need atmospheric testing in a confine space. This test can make a difference between life and death.
OSHA standard 29 CFR 1910.146 (c) subsection (C) states: Before an employee enters the space, the internal atmosphere shall be tested, with a calibrated direct-reading instrument, for the following conditions in the order given: (1) oxygen content, (2) flammable gases and vapors, and (3) potential toxic air contaminants.
In obedience to this regulation, atmospheric testing must be done; and to verify the accuracy of this atmospheric testing, bump test must be carried out on the gas detector.
There are lots of reasons why a portable gas detector may not react to gas, some of which may not be obvious when you pick up a unit. The safest way to make sure your gas monitor is working is to test it.
How to do a bump test
Here is a very short, concise and self-explanatory video about the bump test:
After exposing the gas detector to a known volume of gas, the reading is compared to the actual quantity of gas released, as stated on the test gas cylinder. If the detector goes into alarm within an acceptable range of the actual concentration, usually within 10%, then it is working safely, but if the bump test results are not within the acceptable range, or it takes more than 30-40 seconds to alarm, the gas detector must not be used until a full calibration has been conducted.
You can read OSHA Calibrating and Testing Direct-Reading Portable Gas Monitors – Here
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