4.0 Tracer Gas
4.1 Helium vs. Hydrogen as a tracer gas
The MGD-2002 is a Helium/Hydrogen detector calibrated to
detect “Helium”. However, it will indeed give readings if hydrogen
is present. As this detector is based on the thermal conductivity
of gasses and with Helium and Hydrogen being similar in this
regard the detector will not be able to tell the difference.
Helium is the preferred tracer gas. Helium is a noble gas and does
not react or combine with any other gas or substance. It is safe to
use in all types of leak locating at any concentration up to 100%.
Hydrogen is not generally present in higher quantities in
uncontrolled situations as it is very reactive and if in quantities
greater then 4% it is very ammable and even explosive. To use
it as a tracer gas you need to purchase it mixed to 4% or less
with the remainder being nitrogen. Thus, starting with an already
diluted tracer gas making it that much harder to nd as it dilutes
even further when you add it to the system being tested. (not
a problem when working with 100% helium) We certainly DO
NOT recommend Hydrogen be used as a tracer gas for these
reasons.
Note: It would take more then 20 tanks of 4% hydrogen mix to
equal the amount of traceable gas in one 100% helium tank.
Mixing the helium down to 4% is certainly an option and can be
done by adding compressed air to the system as it is being lled.
4.2 Other Gases the MGD-2002 will react to
When considering all other gasses there are some that would
normally present false reading when in high concentrations such
as CO, CO2 and Ozone (on a busy street) with helium detectors
using this above mentioned sensor type. However, we looked at
this situation based on our experience with older models of our
detectors and through the development of some patented lter
media combinations and custom software we have eliminated or
captured these gasses eliminating the majority of false readings.
Unfortunately methane even in very low concentrations can
cause the MGD-2002 to react but this is generally only seen
during certain environmental tests.
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