
12 EN
11. Leak detection methods
The following leak detection methods are deemed acceptable for systems containing
ammable refrigerants.
Electronic leak detectors shall be used to detect ammable refrigerants, but the sensitivity
may not be adequate, or may need re-calibrated.(Detection equipment shall be calibrated in
a refrigerant-free area.) Ensure that the detector is not a potential source of ignition and is
suitable for the refrigerant used. Leak detection equipment shall be set at a percentage of the
LFL of the refrigerant and shall be calibrated to the refrigerant employed and the appropriate
percentage of gas(25% maximum )is conrmed .
Leak detection uids are suitable for use with most refrigerants but the use of detergents
containing chlorine shall be avoided as the chlorine shall be avoided as the chlorine may react
with the refrigerant and corrode the copper pipe work.
If a leak is suspected, all naked ames shall be removed/extinguished.
If a leakage of refrigerant is found which requires brazing, all of the refrigerant shall be
recovered from the system, or isolated (by means of shut o valves) in a part of the system
both before and during the brazing process.
12. Removal and evacuation
When breaking into the refrigerant circuit to make repairs- or for any other purpose –
conventional procedures shall be used. However, it is important that best practice is followed
since ammability is a consideration. The following procedure shall be adhered to:
remove refrigerant;
purge the circuit with inert gas;
evacuate;
purge again with inert gas;
open the circuit by cutting or brazing;
The refrigerant charge shall be recovered into the correct recovery cylinders. The system shall
be “ushed’ with OFN to render the unit safe. This process may need to be repeated several
times. Compressed air or oxygen shall not be used for this task.
Flushing shall be achieved by breaking the vacuum in the system with OFN and continuing
to ll until the working pressure is achieved, then venting to atmosphere, and nally pulling
down to a vacuum. This processing shall be repeated until no refrigerant is within the system.
When the nal OFN charge is used, the system shall be vented down to atmospheric pressure
to enable work to take place. This operation is absolutely vital if brazing operations on the
pipe-work are to take place. Ensure that the outlet for the vacuum pump is not close to any
ignition sources and there is ventilation available.
In addition to conventional charging procedures, the following requirements shall be followed.
-Ensure that contamination of dierent refrigerants does not occur when using charging
equipment. Hoses or lines shall be as short as possible to minimize the amount of refrigerant
contained in them.
-Cylinders shall be kept upright.
-Ensure that the refrigeration system is earthed prior to charging the system with refrigerant.
-label the system when charging is complete (if not already)
-Extreme care shall be taken not to overll the refrigeration system.
Prior to recharging the system is shall be pressure tested with OFN. The system shall be leak
tested on completion of charging but prior to commissioning. A follow up leak test shall be
carried out prior to leaving the site.
Before carrying out this procedure, it is essential that the technician is completely familiar
with the equipment and all its detail. It is recommended good practice that all refrigerants
are recovered safely. Prior to the task being carried out, an oil and refrigerant sample shall be
taken is case analysis is required prior to re-use of reclaimed refrigerant. It is essential that
electrical power is available before the task is commenced.