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REFRIGERANTS


Making the change


Aermec’s Paul Osborne takes a look at flammables and reviews how the industry is adapting.


T


he HVACR industry has for some time been migrating towards more environmentally friendly materials. Both refrigerant manufacturers and system developers have worked hard to replace the older classes of refrigerants with less damaging and greener refrigerants that have a lower impact on global warming and do not deplete the ozone layer. Many of the new refrigerants have been classified as flammable, which raises concerns particularly amongst end users who may not be aware of or understand the differing levels of classification and the levels of risk.


Our industry has made enormous strides in embracing new refrigerants. Equipment manufacturers have worked hand-in-hand to develop components and systems that can handle a specific refrigerant’s technical challenges and performance levels. The transition from R22 to R410A was just such a development towards a greener pathway. While R410A is not a natural refrigerant, in many ways it spearheaded the drive to seek out alternatives. Many of the new and, in some cases, not so new alternatives that have come into the spotlight, are naturally occurring, non-synthetic materials, including the hydrocarbons such as propane, butane but also CO²


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ammonia, air and water. These offer many benefits, but they also created a new set of challenges for the industry. Some contractors and end users are resistant to having flammable material in their systems. Some have been put off because the use of flammable refrigerants in equipment may invalidate business insurance policies (how many insurance companies really understand the flammability and toxicity classifications?). So, it is incumbent upon the industry to educate so that informed decisions can be made.


Education can go a long way to unravelling the confusion. Some natural refrigerants are more efficient for a/c applications whilst others are more efficient for refrigeration. There is no panacea or one size fits all; little


40 March 2019


wonder it can be so confusing. Flammability alarm bells ring when customers move to a lower GWP refrigerant. They do not appreciate that there is often a trade-off between flammability and the energy efficiencies. This needs to be explained. Understanding what is meant by flammability and the associated risks is a good place to start.


Flammability is a measure of a substance’s ability to burn or ignite, causing a fire or combustion. The degree to which the substance is flammable depends on the upper and lower flammability limits and the energy supplied for ignition. Lower flammability limit (LFL) defines the minimum amount of refrigerant that is capable of propagating a flame. Upper flammability limit (UFL) is the highest concentration of gas or vapour in the air that is capable of producing a flame in the presence of an ignition source.


ASHRAE’s standards and safety classification sets out classes of refrigerants based on their flammability and toxicity. There are several classes ranging from non- flammable A1 to highly flammable A3, depending on the refrigerant’s LFL value, heat combustion and burning velocity.


Toxicity is indicated by the letters A and B, designating lower and higher toxicity whilst the numbers 1, 2 and 3 denote the level of flammability from none, lower and higher flammability, respectively. R290, for example, has an A3 classification as it has a low toxicity but high flammability rating.


The International Organisation for Standards (ISO) has its own standard in the form of ISO 817 which also assigns safety classifications to refrigerants based on their toxicity and flammability data. Similarly, BS EN378, published by the European Committee for Standards (CEN), is a safety and environmental standard that provides guidance for companies engaged in the design, construction, installation, operation and maintenance and use of vapour


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