Leak Testing with OFDN and weak soapy water solution
This method consists of pressurising the empty refrigerant circuit with a rea-
sonably high pressure of OFDN gas. A pressure, usually up to 10 bar (150 PSI)
is applicable. The subsequently carried out Leak Test using a weak soapy water
solution shall cover all potential areas of possible leakages.
Provide a filled Nitrogen cylinder (containing OFDN gas) equipped with reliable
pressure regulator and Nitrogen transfer hose (N), having a ¼” SAE female
adapter and with Schrader valve core depressor.
The warning sign is still placed in the work-area because we are now handling a
pressurised cylinder (about 250 bar) and OFDN gas is intentionally blown off
from the system to the ambient area.
It is advisable to have an intermediate pressure gauge, equipped with control
valve, within the Nitrogen transfer hose (N) to be separated from the pressure
regulator and the OFDN gas cylinder. This arrangement will enable you to carry
out a “Standing Pressure Test” and after a period of time to identify whether or
not the pressure drops during this time within the AC system (or specific sepa-
rated parts of the system). Fortunately, the dry Nitrogen charge in the AC sys-
tem experiences a very little pressure change when the AC system is exposed
to small temperature changes with the environment. This procedure may enable
you to verify that the system, or separated parts of it, is free of leaks.
Example of an intermediate
(Hose N) pressure gauge for
“Standing Pressure Test”. The
stop-valve enables you to
separate the gauge from the
OFDN gas cylinder and to
check the refrigerant circuit by
pressurising with OFDN for
“pressure fall” in a
certain period of time.
L
N
Never switch
ON the AC
system if
charged with
OFDN!
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