26
Response to Refrigerant
After checking the alarms, the next step is
to check for a proper response to the
presence of a refrigerant. This will be done
by preparing a sample of refrigerant for
testing, and then presenting it to the system
to make certain it measures refrigerant. It
is suggested the following steps are
completely reviewed before starting. This
test is best done after the monitor has been
running normally for an hour or two.
Step 1:
Remove the inlet tubing from the
sample inlet.
Step 2:
Prepare a refrigerant sample.
Note
that
refrigerants
can
be
Chlorofluorcarbons
(CFC's),
Hydrochlorofluorocarbons
(HCFC's)
or
Hydrofluorocarbons (HFC's). HFC's are the
only refrigerants considered to be truly
"Ozone Friendly". Because of this,
SenTech Corporation recommends use of
an HFC, such as R134A for field-testing of
the IR-SNIF series of monitors. Any field-
testing of a refrigerant monitor, by its very
nature, will release an amount of refrigerant
into the environment through the exhaust
port of the monitor.
Caution: Follow all national and
local codes for safe handling of
refrigerants.
Because the IR-SNIF-MCD is factory
calibrated, and no field calibration is
necessary, the refrigerant sample is not
required to be of a known level. A
calibrated "test gas" kit is available from
SenTech Corporation, should the user
desire to perform the following tests with a
sample of known PPM level. The following
paragraphs describe a procedure for
preparation of a refrigerant sample using
pure refrigerant.
Three items are needed to prepare a
sample:
A Refrigerant
A Container
A short piece of 1/4" Tube.
The Refrigerant should be available on-site,
but if not, R-134A is readily available at
local stores. Note that many local office
supply stores sell a 'pressurized air duster'.
Often, this product is simply pressurized
Tetrafluoroethane, or R-134A. This is a
cost effective, readily available source of
pure test gas, as long as the contents have
been verified to be Tetrafluoroethane.
The sample container may also be
available
on-site.
Suitable
sample
containers range from lab quality sealed
bags with twist valves to a simple plastic
bag or even an open top jar or can. The
container should be at least 4 liters, or
about a gallon. The container should be
able to be loosely closed, e.g. twisting a
plastic bag, or closing a lid.
The 1/4 inch tubing should be long enough
to connect to the sample inlet and extend
into the bottom of the sample container.
Because refrigerants are heavier than air,
pulling the sample from the bottom of the
container will ensure introduction of the
refrigerant into the selected zone.
a) Gaseous Refrigerants: Insert a
refrigerant fill hose into the container
opening. Crack the valve for a second or
less so that a small squirt of refrigerant
enters. Keep in mind that the monitor reads
in PPM (parts per million) and a tiny amount
of gas will make a relatively high
concentration sample. Pull out the hose,
and loosely close the container.
Содержание IR-SNIF-MC-1
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