Some confustion: I will start by trying to iron out some confusion about the gases used in airsoft. Firstly 22 (or R22 as I call it) was, and still is the most common gas found in fridges and air-conditioning systems. However in recent years it has been found that R22 has ozone depleting properties, so there were new gases created - 404a and 134a which were not ozone depleting. (When I say 22 is ozone depleting I mean when it is released in vast amounts not such as those using airsoft). There are many other equivalents to these gases see table below.

A few myths: With regard to the corrosiveness of the gases in relation to Airsoft - to the best of my knowledge 22 has no corrosive properties in relation to airsoft. 404a and 134a do crystallise ordinary everyday mineral oil so it is important that synthetic oil is used and also there is a small amount of synthetic oil in the gas itself. There is a replacement gas called R49, which can be used with mineral oil. If the rubber in your particular gun is synthetic then there will probably be nothing to worry about regarding corrosion from 134a and 404a.

So why is HFC134a weaker? It has come to my attention recently that not many people use 134a because it is a “weaker” gas. Let me explain why this is. All refrigerant gases are in liquid form when they are in their containers. All refrigerant gases also have a standard pressure. This standard pressure is the term used to indicate the temperature at which the liquid changes state (goes from being in liquid form to gas form, or when it evaporates). This evaporation temperature is different in the gases. R22 and 404a have an evaporation temperature of -41°C. 134a and R49 have an evaporation temperature of -21°C. For example if you has a bowl of water and a bowl of petrol and left them in a room, the petrol would evaporate first because the temperature at which petrol evaporates is lower than that of water. So what has this got to do with airsoft then? You may ask. Prepare for the science lesson.

So you skipped science class? You see the gas particles in your gas gain energy from heat the more energy they gain (or the hotter they get) the more they move about. This is where the evaporation points come into play. 22 and 404a have an evaporation point of -41°C. It is when the liquid reaches this temperature that the particles gain enough heat energy to fly off and become a gas. Then after that every little increase in the temperature gives the particles more energy. The more energy they have the more they fly about and thus there is more pressure created.

If we put the two gases 134a and 22 side by side you would see that at -41°C 22 would begin to evaporate and 134a would remain in it’s liquid state until the temperature has reached -21°C. So the 22 has always got a head start of 20°C. Unless of course the 134a is heated a further 20°C in which case the pressures of the two gases would be the same.

When it comes to the prices of gas then obviously 22 is the cheapest as this is the cheapest to produce and has also been around for years so it is used in a lot of things. 134a, 404a and R49 are all much more expensive because they have properties which make them more expensive to manufacture.

New gases? Before I bring this article to a close I would just like to bring to your attention that a new gas is being developed. It is a high pressure gas called R410 and is to be used as an alternative to 22 and 404a. As yet I do not know much about this gas nor do I know of it’s relevance to airsoft.

Conclusion: I hope that you have enjoyed reading this and that it has helped you to learn more about gases and how they are used. If you have any questions or comments then feel free to e-mail me at achubb@talk21.com