RACA Journal I June 2026 www. refrigerationandaircon. co. za 41
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• Leak detection fluids are suitable for use with hydrocarbon refrigerants but the use of detergents containing chlorine should be avoided as the chlorine may react with the refrigerant and corrode the copper pipework.
• Oil additives such as those used in fluorescent leak detection systems will operate with hydrocarbons.
• If a leak is suspected from a hydrocarbon refrigerant system all ignition sources should be removed. If a leakage of refrigerant is found which requires brazing, all of the refrigerant shall be removed from the system, or isolated by means of shut-off valves, in a part of the system remote from the leak.
• Nitrogen should then be purged through the system both before and during the brazing process.
Pipe connections: Eliminate flared connections or compression fittings wherever possible. Use brazed joints only.
No ignition sources: Prior to work taking place, the area around the equipment is to be surveyed to establish any flammable hazards or ignition risks. No person carrying out work in relation to a refrigeration system which involves exposing any pipe work which contains or has contained flammable refrigerant shall use any sources of ignition in such a manner that it may lead to the risk of fire or explosion. All possible ignition sources, including cigarette smoking, should be sufficiently far away( 2.5 – 3m) from the site of installation, repairing, maintaining from which flammable refrigerant could be released into the surrounding space.
Ventilated area: Ensure that the area is in the open or that it is adequately ventilated before breaking into the system or conducting any hot work. A degree of ventilation should continue during the period that the work is carried out. The ventilation should safely disperse any released refrigerant and preferably expel it externally to the atmosphere. Portable fans can be used to disperse the refrigerant. Venting should be done to an outdoor area where it is safe to do so.
Checks of the refrigeration equipment: Where electrical components are being changed, they are to be‘ fit for purpose’ and to the correct specification. At all times the manufacturer’ s maintenance and service guidelines are to be followed. If in doubt consult the manufacturers for assistance. The following checks should be applied to installations using flammable refrigerants:
• That the charge size is in accordance with the room size within which the refrigerant containing parts are installed.
• That ventilation machinery and outlets are operating adequately and not obstructed.
• Confirm operation of equipment such as refrigerant leak detectors and mechanical ventilation systems.
• If an indirect refrigerating circuit is being used, the secondary circuit should be checked for the presence of refrigerant.
• Ensure that labelling of the equipment continues to be visible and legible.
• Refrigeration piping or components must not be installed in a position where it is likely to be exposed to any substance which may corrode refrigerant containing components.
Checks of electrical devices: Intrinsically safe components are the only types that can be worked on while live in the presence of a flammable atmosphere. However, test apparatus should also be of an appropriate rating. Replace only with parts specified by the manufacturer. Other parts may result in the ignition of refrigerant in the atmosphere from a leak. Check that cabling will not be subject to wear corrosion, excessive pressure, sharp edges or any other adverse environmental effects. This should also take into account the effects of ageing or continual vibration from sources such as the compressor or fans.
Breaking into a system and charging: When breaking into the refrigerant circuit conventional procedures are used. However, it is important that best practice is followed since flammability is now a consideration. The following procedure shall be adhered to:
• Remove refrigerant
• Purge the circuit with inert gas( nitrogen)
• Evacuate
• Purge again with inert gas
Once the refrigerant charge is removed the system is then to be flushed with nitrogen to render the unit safe, this process may need to be repeated several times. On no account use compressed air or oxygen for this task. Flushing is achieved by breaking the vacuum in the system with nitrogen and continuing to fill until the working pressure is achieved, then vent to atmosphere and finally pulling down to a vacuum. This process is repeated until satisfied that no hydrocarbons are within the system. When the final nitrogen charge is used, the system can be vented down to atmospheric pressure to enable work to take place. This operation is absolutely vital if brazing operations on the pipework are to take place. Ensure that the outlet for the vacuum pump is not close to any ignition sources and that there is ventilation available.
Charging: Prior to recharging the system it should be pressure tested. The system must be leak tested on completion of charging but prior to commissioning. A follow-up leak test should always be carried out prior to leaving site. The charging of refrigeration systems with hydrocarbon refrigerants is similar to those using traditional refrigerants. The following additional requirements should be adhered to:
• Ensure that contamination of different refrigerants does not occur when using charging equipment. Hoses or lines are to be as short as possible to minimise the amount of refrigerant contained in them.
• It is recommended that the refrigerant is charged in the liquid phase where possible.
• Ensure that the refrigeration system is earthed prior to charging the system with refrigerant.
• The refrigerant should be weighed into the system using an accurate refrigerant scale.
• Label the system when charging is complete. The label should state that hydrocarbon refrigerants have been charged into the system, the quantity and that it is flammable. Position the label in a prominent position on the equipment.
• Extreme care shall be taken not to overfill the refrigeration system. Note that hydrocarbon charge sizes are typically 40 – 50 % of HCFC and HFC charge sizes.
Commissioning: A refrigeration system containing hydrocarbon is commissioned in exactly the same manner as systems containing HFC / HCFC refrigerants. Ensure that correct marking is applied to the system. voices
RACA Journal I June 2026 www. refrigerationandaircon. co. za 41