Everything comes at a price. Especially when talking about increasing the quantity of a flammable substance in supermarket refrigerators, which are accessible to everyone. This was the responsibility assigned to the working group in charge of updating standard IEC 60335-2-89. 

 
In essence, the objective of the 26 working group members from 13 countries was to define the maximum amount of flammable refrigerant and the measures needed to maintain an equivalent safety level in commercial refrigeration appliances. The project started in 2014, and the new version was finally published on the IEC website on 20 June this year. “This new standard will allow systems manufacturers to comply with present and future regulations, phasing out high-GWP refrigerants globally in this specific market segment” noted Zgliczynski, chair of the IEC SC61C subcommittee.

The price to pay includes new measures and tests for all equipment, especially units with more than 150 grams of flammable refrigerant.

A brief look at the news

The modification on everyone’s lips is that the charge limit of propane has increased from 150 to 500 grams. This is just an example of what the standard specifies: the charge limit when using flammable refrigerants increases from 150 g to the minimum between 13×LFL or 1.2 kg. This means that 500 grams is the maximum charge allowed in commercial appliances containing propane, as the LFL of propane is 0.038 kg/m³. Thus, when using refrigerants with a LFL higher than 0.092 kg/m³, such as A2 and A2L, the maximum charge allowed is 1.2 kg. It is important to note that split systems, which are appliances with a remote refrigeration unit or compressor, are the exception and will still have a charge limit of 150 grams. 

As regards appliances, commercial ice makers have been included in the new version. Other appliances within the scope of the standard are refrigerated display and storage cabinets, refrigerated trolley cabinets, service/self-service counters, and blast chillers/freezers.

Another big change is that mildly flammable refrigerants (A2L) are included. They had already been included in other standards, such as IEC 60335-2-40, facilitating their use with respect to more flammable refrigerants, such as A2 and A3.

Regardless of the flammability classification, hermetically-sealed systems are compulsory for all appliances with flammable refrigerants. The issue is that a test for leaks must be carried out on all site-made joints, using detection equipment with a sensitivity of at least 3 g/year of refrigerant. Additionally, all connections, capped valves and capped service ports in a hermetically-sealed system must comply with ISO 14903 tightness control level A1. It should be noted that this is the only test that applies to all appliances with flammable refrigerants, regardless of the refrigerant charge.

Needless to say, safety first

Appliances with more than 150 grams of flammable refrigerants will have to comply with additional requirements in order to ensure that the risk will not increase when using the additional charge.

 
To start with, a test that guarantees an adequate mechanical impact withstand strength of external surfaces that are adjacent to or in contact with parts containing refrigerant needs to be applied. The objective is to verify that the parts containing refrigerant are protected and not accessible.

Another test is required to evaluate vibration or resonance points in the piping connected to the compressor. If there are no variable-speed compressors in the appliance, the supply frequency is adjusted in 1 Hz steps between 0.9 times and 1.1 times the rated frequency. For appliances with variable-speed compressor, the supply frequency from the inverter to the compressor is increased in 1 Hz steps from the minimum frequency to the maximum frequency over the speed range of the appliance.

The fourth test for an appliance with more than 150 grams of flammable refrigerants has the goal of proving that the gas concentration outside of the boundary of the appliance is never higher than 50% of the LFL for more than 5 minutes. In this test, refrigerant is leaked from any critical point, including one inside the refrigerated space with the door or drawers closed. After a period of 30 seconds at the end of the leak, the door or drawer shall be opened at a uniform rate over 3 seconds (except for automatic doors, which are opened at the maximum speed setting). The measurements are taken at six points in the appliance and two outside, one at the front and one at the rear.

As may be suspected, air flow may be necessary to pass this test. The new standard specifies that air flow must be produced by components that are part of the appliance. In any case, considering the solutions that are currently available, it does not seem easy to pass the test with 500 grams of A3 refrigerants for cabinets with doors. Hence, the maximum cooling capacity of closed cabinets with propane will be approximately equivalent to the maximum cooling capacity of open cabinets. 

Finally, if compliance relies on the operation of an electronic circuit, this test has to be repeated both while simulating/forcing fault conditions of the electronics, applied one at a time, and while carrying out the EMC tests, as described in the original standard IEC 60335-1.

Don’t forget…

In addition to all of these are the other compulsory tests that had already been specified in previous versions of this standard, such as the one for appliances with electrical components that generate arcs or sparks outside of the food storage compartments.

Other requirements specified in the standard, such as the mark and instructions to be placed on the appliance, will complete the list of measures to take into account when designing a cabinet with flammable refrigerants. 

To conclude, it must be remembered that this is an international standard, IEC 60335-2-89. Now it is time for different countries to update their national standards, such as EN 60335-2-89 in Europe or UL 60335-2-89 in the USA, as well as the related legislation. After this it will be interesting to see the response from the market… will the cost of 500 grams of propane be fair?

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