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4. WIRING
Make sure that the wiring will not be subject to wear, corrosion, excessive pressure, vibration,
sharp edges or any other adverse effect on the environment. The verification should also take into
account the effects of aging or continual vibration from sources such as compressors or fans.
5. 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 using an open flame) should not be used.
6. LEAK DETECTION METHODS
The following leak detection methods are considered acceptable for systems containing
flammable refrigerants. Electronic leak detectors should be used to detect flammable refrigerants,
but the sensitivity may not be adequate or require recalibration (detection equipment should be
calibrated in an area without refrigerant). Make sure that the detector is not a potential source of
ignition and that it is suitable for the refrigerant used. Leak detection equipment should be set to a
percentage of the LLI of the refrigerant and should be calibrated with the refrigerant being used
and the correct gas percentage (25% maximum) is confirmed. Leak detection fluids can be used
with most refrigerants, however, the use of detergents containing chlorine should be avoided as
chlorine can react with the refrigerant and cause corrosion of copper pipes. If a leak is suspected,
all open flames should be removed / extinguished. If a refrigerant leak requiring brazing is
detected, all refrigerant should be recovered from the system or isolated (by means of shutoff
valves) in a part of the system remote from the leak. The oxygen free nitrogen (OFN) must then
be purged through the system before and during the brazing process. If a refrigerant leak requiring
brazing is detected, all refrigerant should be recovered from the system or isolated (using shutoff
valves) in a part of the system remote from the leak. The oxygen free nitrogen (OFN) must then
be purged through the system before and during the brazing process. If a refrigerant leak requiring
brazing is detected, all refrigerant should be recovered from the system or isolated (by means of
shutoff valves) in a part of the system remote from the leak. The oxygen free nitrogen (OFN) must
then be purged through the system before and during the brazing process.
7. DRAINING AND EVACUATION
When entering the refrigerant circuit for repairs - or for any other purpose - use standard
procedures. However, it is important to follow best practices as flammability is a factor to consider.
The following procedure must be observed: drain the refrigerant; purge the circuit with inert gas;
clear out; purge again with inert gas; open the circuit by cutting or soldering. The refrigerant
charge must be recovered in the correct recovery bottles.
The system must be "flushed" 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. Draining
should be accomplished by breaking the vacuum in the system with OFN and continuing to fill until
operating pressure is reached, then releasing into atmosphere and ultimately pulling vacuum. This
process should be repeated until there is no more refrigerant in the system. When the last OFN
charge is used, the system must be vented to atmospheric pressure to allow work to be
performed. This operation is absolutely vital for brazing work to be carried out on the piping.
8. CHARGING PROCEDURES
In addition to conventional charging procedures, the following requirements must be observed.
• Make sure that the various refrigerants are not contaminated when using charging equipment.
Pipes or conduits should be as short as possible to minimize the amount of refrigerant they
contain.
• The bottles must be kept upright.
• Make sure the refrigeration system is grounded before charging it with refrigerant.
• Label the system when charging is complete (if not already done).
• Care should be taken not to overfill the refrigeration system.
Before recharging the system, it should be pressure tested with OFN. The system should be leak
tested at the end of charging but before commissioning. A leak test must be carried out before
leaving the site.
EN-11
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