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pressors or fans.
Detection of flammable refrigerants
Under no circumstances should potential ignition sources be used to search for or
detect refrigerant leaks. A halide torch (or any other detector that uses an open flame)
should not be used.
Leak detection methods
The following leak detection methods are considered acceptable for systems containing
flammable refrigerants.
Electronic leak detectors must be used to detect flammable refrigerants, but sensitivity
may not be adequate or recalibration may be required. (The detection equipment must
be calibrated in an area without refrigerant). Make sure the detector is not a potential
source of ignition and is suitable for the refrigerant used. The equipment for the de-
tection of leaks must be set to a percentage of the LFL of the refrigerant and must be
calibrated on the refrigerant used and the appropriate percentage of gas is confirmed
(25% maximum).
Leak detection fluids are suitable for use with most refrigerants, but the use of chlorine-
containing cleaners should be avoided since chlorine could react with the refrigerant
and corrode the copper piping.
If a leak is suspected, all open flames must be removed / extinguished.
If a refrigerant leak is detected that requires brazing, all refrigerant must be recovered
from the system or isolated (via shut-off valves) in a part of the system away from the
leak.
The oxygen-free nitrogen (OFN) must therefore be purged through the system both
before and during the brazing process.
Removal and evacuation
When breaking into the refrigerant circuit to make repairs or for any other purpose,
conventional procedures must be used. However, it is important to follow best practices
since flammability is a consideration. The following procedure must be followed:
1-Remove the coolant.
2-Purge the circuit with inert gas.
3-Evacuate.
4-Purge again with inert gas.
5-Open the circuit by cutting or brazing
The refrigerant charge must be recovered in the correct recovery cylinders. The system
must be “washed” with OFN to make the unit safe. It may be necessary to repeat this
process several times. Compressed air or oxygen should not be used for this task.
The washing must be obtained by breaking the vacuum in the system with OFN and
continuing to fill until the operating pressure is reached, then discharging into the at-
mosphere and finally lowering the vacuum. This process must be repeated until there is
no more refrigerant inside the system. When the final OFN charge is used, the system
must be vented to atmospheric pressure to allow the work to be carried out. This ope-
ration is absolutely essential if you want to carry out brazing operations on the pipes.
Make sure that the vacuum pump outlet is not close to ignition sources and that there
is ventilation available.
Charging procedures
In addition to conventional debit procedures, the following requirements must be fol-
lowed.
Make sure that contamination of different refrigerants does not occur when using char-
ging equipment. Hoses or lines should be as short as possible to minimize the amount
of refrigerant they contain.
Cylinders must be kept upright.
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