A2L refrigerants are particularly useful for applications such as convenience stores, but working with them requires understanding of their characteristics and good preparation, says Nabil Cook, Technical Director for Omega Solutions.
Whichever refrigerant camp you sit in, A2Ls have their place on the current market, especially for smaller convenience store systems, which rarely exceed condensing units or mini-pack scale and have limited interconnecting service runs. A2L refrigerants are predominantly HFO-based, with low GWPs (<300) compared to other fluorinated fluids (except for R32 which is a single-component HFC with a relatively high GWP of 675). They exhibit lower flammability and, therefore, require a bit more work than non-flammable A1 refrigerants.
Preparation is key to ensuring the safe, compliant, and effective use of A2L refrigerants. Understanding the essential requirements and how they differ from an A1 solution is crucial, yet this does not need to be a minefield.
This article focuses on A2L-ready refrigeration plant. Some UK manufacturers are already producing high-quality A2L-ready refrigeration plant solutions – so this guide is aimed at those who are not doing so currently but are considering diversifying in the future. Please note that this is a non-exhaustive indicative guide only. You are expected to do due diligence in reviewing standards, legislation, and guidance and conducting the appropriate risk assessments.
Let’s delve into the heart of the system – the compressor. Compressors play a pivotal role in refrigeration systems and must be carefully selected for their suitability with A2L/HFO refrigerants in terms of flammability mitigation and material compatibility. This may involve using different gasket materials and adjusting the maximum temperature of the crankcase heater. Inverters and head cooling fans (if present) may also require additional levels of electrical compliance to obtain suitability for A2Ls.
Then, we move on to other key components: the condenser, the receiver, and other pressure vessels. These must be suitable and labelled for A2Ls/B2Ls and PED Group 1 fluids, which changes the category calculation boundaries – potentially leading to microchannel condensers instead of traditional finned-tube variants. Are the condenser fans ATEX-rated, suitable for flammable refrigerants, or just standard? This depends on the results of your risk assessment, which will refer to the condenser positioning and orientation, among other things.
A complete pump-down receiver is not advisable: the vessel should now comprise a significantly lower volume surge drum to suit BS EN 378 charge size limitations. This can still buffer refrigerant if appropriately sized according to load and saturated temperature shifts. Other pressure vessels affected may include oil separators, suction accumulators, and plate heat exchangers.
In addition to plant housing leak detection, an ATEX Zone plant housing extract fan is usually required for these solutions. A description or drawing of leak detection positioning should be included, and suitability for A2L refrigerant type and combustibility should be ensured. The leak detector semiconductor or catalyst must be the right one. Warning ahd shut-down PPM levels must be correct for the refrigerant and accompanied by clear operational and maintenance instructions for relevant personnel.
A segregated electrical panel housing is likely to be required to prevent combinations of spark and leak potential points. The coating, IP rating, and electric shock protection on panels require careful consideration.
Then there are the little things like oil level regulators, pressure switches, glanding, conduits, and cable seals. Such componentry may need to be enhanced to suit A2L refrigerants. Pressure relief valves and any associated change-over valves must be positioned away from significant powered heat sources and electrical equipment.
The other half of the battle is documentation, notes, certification, and labelling. These things are still mandated for A1 refrigerant systems, but they almost take on a new life when done for A2Ls. Remember to state the allowed working refrigerant(s), the anticipated refrigerant charge required on-site, its safety classification, MSDS, safety datasheets, technical datasheets, and its constituent makeup. Supply DSEAR zoning layouts and area classification diagrams for plant areas from multiple perspectives/projections accompanied by a statement referencing positioning, allowing sufficient room, and avoiding obstructions and potential ignition sources.
Include all nameplate labels, specifications, drawings, declarations of conformity and incorporation, manufacturer declarations, technical manuals, operating instructions, application guidelines, safety instructions, safety assembly instructions, and replacement guidelines.
Think “warning-prevention-response,” including suitable extinguishing methods. Prominent notes on emergency services and evacuation are a must. Installation, commissioning, service, and maintenance engineers should be warned to use approved machinery and leak detection equipment for A2L, such as compliant torque wrenches and other spark-free, lower-grade heat equipment. Reference the storage, recovery and disposal of refrigerant, hot works, portable gas detectors, ensuring good ventilation, and demand and define the full competency and training of engineers and other personnel. Finally, clear communication and instruction should be provided to all store staff and other staff working in the local area.
As you will see, it isn’t difficult! At the heart of this, much of the above still needs to be considered for non-flammable solutions, even if the tangible outcome and conveyed message vary greatly.
