Fire safety with hydrocarbon refrigerants (R290 and R600a)

How flammable refrigerants are classified

Refrigerants are classified under ISO 817 by toxicity and flammability. R290 and R600a are class A3: lower toxicity, higher flammability. Many traditional HFCs are A1, non-flammable. The flammability means a leak could, in the wrong conditions, form a mixture with air that burns if it meets an ignition source.

The key words are 'in the wrong conditions'. A plug-in cabinet holds a small charge in a sealed system, and for a fire risk the refrigerant would have to leak, collect in a confined space at a concentration within its flammable range, and meet a spark or flame at the same time.

Charge limits and design safeguards

Safety standards limit how much flammable refrigerant a commercial appliance can contain. IEC 60335-2-89, the international safety standard for commercial refrigerating appliances, was revised in 2019 to allow up to 500 g of A3 refrigerant per circuit (previously 150 g), with extra design and testing requirements and conditions on room size. Whether and how this is adopted varies by country.

Manufacturers also design electrical components in the cabinet so they cannot ignite leaked refrigerant, and they mark units with the refrigerant type and a flammable warning. Your part is to install and service the unit as the manual says.

Installation good practice

• Follow the manual's minimum room size or ventilation requirement, if stated; it is part of the safety design.
• Do not install in small, closed, unventilated cupboards or rooms unless the manufacturer allows it.
• Keep naked flames, gas burners, tandoors and spark-producing equipment away from the unit's machine compartment.
• Do not place the unit in a basement pit or low enclosure where leaked gas, which is heavier than air, could pool.
• Do not drill, screw or cut into the cabinet; refrigerant pipes run inside the walls.
• Use the supplied plug and a proper socket; do not modify cabinet wiring.

Service must be done by trained technicians

Working on a hydrocarbon system is different from working on an HFC system. The technician needs training in flammable refrigerants, a leak detector suitable for hydrocarbons, tools that will not cause sparks, good ventilation and a safe procedure to remove refrigerant before any brazing. Brazing on a system that still holds refrigerant is a serious fire risk.

Ask your service provider whether their technicians are trained and equipped for R290 and R600a. Do not let a general technician 'top up' a hydrocarbon unit with a different refrigerant; mixing refrigerants is unsafe and damages the system.

If you suspect a leak

Hydrocarbon refrigerants are odourless in pure form, so you are unlikely to smell a leak. Signs are usually indirect: the unit stops cooling, runs constantly or shows oily residue at joints. Most leaks in sealed plug-in units are slow and release small amounts that disperse. If you suspect a significant leak in a confined space, ventilate the room by opening doors and windows, keep flames and sparks away, do not switch electrical equipment on or off in that room, and call a qualified technician.

Fire preparedness in the kitchen

• Keep the area around refrigeration free of stored cardboard, oil cans and LPG cylinders.
• Maintain fire extinguishers suitable for the kitchen and train staff to use them.
• Keep condensers clean; dust and grease on hot components are a fire risk with any refrigerant.
• Check plugs and sockets for overheating; electrical faults are a far more common fire cause than refrigerant.

Moving, scrapping and disposal

When a hydrocarbon unit is scrapped, the refrigerant should be removed safely by a trained technician before the cabinet is cut up. Scrap dealers using gas cutters on a charged system risk a flash fire. Tell whoever takes the old unit that it contains a flammable refrigerant.