38 RACA Journal I May 2026
SUPPORT
Charge size requirements for various location categories Systems with a charge size of 0.15kg or less can be installed in any size of room. For systems with charge size of more than 0.15kg the room size should be such that a sudden catastrophic loss of refrigerant shall not raise the mean average concentration in the room above the practical limit( approximately 0.008kg / m 3).
Safety standards and codes of practice There are a number of codes and safety standards that are appropriate to the use of flammable refrigerants and related equipment. The selection of appropriate documents is not always obvious and therefore the objective of this section is to provide a degree of clarity in this area.
Refrigerant charge Under no circumstances should the system be overcharged.
System location Attention should be given to the location of hydrocarbon systems in particular, that units are not installed adjacent to opening doors or windows which could result in leaking refrigerant migrating directly into the building. They should also not be located adjacent to drain gulleys or air vent bricks in building foundations due to the heavier-than-air nature of the refrigerants which, in the event of leakage, could see the refrigerant drawn into the drainage system and become highly dangerous. Manufacturer’ s installation guidelines should always be strictly adhered to. Although these refrigerants are classed as non-toxic, they are heavier than air and will readily displace air in a room where leaking refrigerant is present. Asphyxia by air being displaced is a real hazard which must be accounted for in any risk assessment you carry out.
Allowable charge size( all) If the charge is more than 0.15kg, then a sudden loss of refrigerant should not raise the mean concentration in the room above the practical limit( 0.008 kg / m 3). The total charge size is governed by the room volume.
When handling highly flammable refrigerants there is a generally accepted principle of having no ignition source within 2.5m of the refrigerant work area. To determine allowable
38 RACA Journal I May 2026