Gas Detection Section 2 Flashcards
note the types of gas sensors
oxygen - GC EC
carbon monoxide - EC GC IR Tube
carbon dioxide - EC GC IR Tube
methane - IR Thermal GC CC
nitrogen - GC
hydrogen sulphide - EC GC Tube
sulphur dioxide - EC GC Tube
hydrogen - GC
nitrogen dioxide - EC GC Tube
how often does the gas detector have to be fully calibrated to NATA standard?
every 6 months
how often does the gas detector have to be tested using known levels of gases? (bump test)
before each shift
electronic gas detectors can be cleaned using what?
damp cloth
soft bristle brush
what could high (condensing) humidity do to an oxygen sensor reading?
give false reading
cause sensor to fail
why is it not advisable to breath over the sensors?
moisture from breath can poison O2 sensor
state 2 advantages an infrared methane sensor has over a catalytic combustion methane sensor
not dependant on oxygen
not cross sensitive
what should an oxygen sensor of a hand held gas detector read?
20.9 %
what is the minimum oxygen level required for correct operation of catalytic combustion sensor?
10%
what is the normal measuring range for Wheatstone Bridge or Pellistor (catayltic oxidation principle) type methanometers?
0% - 5% total volume
name 2 gases that could cause ‘cross interference’ on a CO sensor?
hydrogen sulphide H2S
sulphur dioxide SO2
what does ‘T90’ refer to when using a personal gas detector?
time take to reach 90% of test gas concentration of no more than 30 seconds
what detector is used to detect Volatile Organic Compounds?
photo ioninization detector PID
what does intrinsic safety mean when using a gas detector?
one that is safe to use in a potentially explosive atmosphere
when would you use a pump style gas detector?
remote sampling
