What is Refrigerant?

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  • Written By: Alan Rankin
  • Edited By: Melissa Wiley
  • Last Modified Date: 04 November 2019
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A refrigerant is a chemical used in cooling systems for mechanical devices such as refrigerators, walk-in freezers, or air conditioners. Most refrigeration units depend on the chemical reactions of refrigerant gas to remove heat from an enclosed area. There are actually numerous gases that have been used as refrigerants. Early refrigerants were highly toxic and dangerous chemicals. The modern gases that replaced them are safer, but many can have a damaging effect on the global environment.

Artificial refrigeration using mechanical and chemical processes was developed in the 19th century. Chemists had long known that some chemical reactions absorb or divert heat, lowering the temperature in a given area. The food and beverage industry of the time needed an alternative to costly and inefficient refrigeration methods involving the transport and storage of ice. Inventors such as American Thaddeus Lowe created complex systems using chemicals to draw heat from enclosed areas, creating a refrigerated compartment. Most of these systems involved some form of refrigerant gas.

A mechanical refrigeration system depends on storing a certain quantity of refrigerant gas or gases. The device creates controlled chemical reactions by forcing the gas to change state or combining it with other chemicals, drawing heat from the refrigerated compartment. Early commercial and home refrigeration units used gases such as ammonia and methyl chloride. These gases are highly toxic and could cause injuries if they escaped containment or required maintenance. For this reason, most early refrigerant gases are no longer in use.


By the 1950s, home refrigeration units were common in most households in developed countries. The manufacturers of these devices replaced toxic refrigerant gases with synthetic refrigerants called chlorofluorocarbons. These were safer to handle and store, but soon scientists discovered they had their own problems. In the 1970s, studies revealed that chlorofluorocarbons used in refrigeration units and other devices contribute to ozone depletion. Ozone depletion, which can increase the damaging health effects of solar radiation, was one of the first environmental crises to be widely understood, and international conventions soon banned chlorofluorocarbons.

Continuing advances in refrigeration technology have produced safe alternative refrigerants and efficient machines that require a fraction of the refrigerant chemicals used by older units. The older refrigerants are still required, however, for older devices that are still in use, such as in cars or industrial freezers. These cannot be converted to modern refrigerants without prohibitive expense. Government bodies such as the United States Environmental Protection Agency have strict regulations on the use and disposal of refrigerants. Individuals requiring the maintenance of refrigeration units should always consult with a qualified technician.


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Post 6

Besides the obvious characteristics of low cost, availability, low toxicity and flammability, a good refrigerant must have a manageable low evaporation and condensation point. It's at the evaporation point and condensation point that the majority (90 percent) of heat is transferred from the load to the refrigerant.

Post 5

@stl156 - Replacing the refrigerant in your automobile is extremely easy once you know how to do it. The one thing I would make sure of first, though, is that the problem actually is low refrigerant. If you lost the cooling very quickly over a couple of days, you probably have a leak in the system, and the coolant you put into the system will just leak out again. Knowingly refilling a cooling system with a leak in it is also illegal.

As far as which refrigerant to use, just check your owner's manual, and it should tell you. If your car was made between the mid 90s and 2010, you probably use the 134a refrigerant. You can go to

any auto supply store and pick up a couple cans of refrigerant and the necessary hoses. I'm sure they'll be glad to help you out. You can also just buy kits that have all the required equipment with it. Good luck!
Post 4

How safe are these different refrigerants for humans to handle? I have been having a problem with the air conditioning in my car, and I was told by a friend that it is relatively easy to replace the refrigerant on your own. I guess that would mean that you can buy the refrigerant in stores, right? Is that the case, or do you have to order it from a special company? I would like to replace the refrigerant on my own if possible, since I think it would be much cheaper.

It sounds like there are tons of different types of refrigerants, though. How do I know which kind that my car has? Also, since these products can be

harmful to the environment, do you have to have any sort of special skills to use them? I just want to make sure that I don't do anything illegal.

Has anyone ever done something like this before? Is it as easy as it sounds, or should I just pay to have someone do it for me?

Post 3

@jcraig - Good questions. As far as the current refrigerants being dangerous to the environment, that is still somewhat the case, I believe. Even though the chemicals aren't as dangerous as the older types, it is still illegal to release them into the atmosphere. I am not sure if that is because they actually are dangerous or because it is just a precaution.

Even though freon itself is no long legal, a lot of people still use the term loosely to describe any type of refrigerant. And yes, scientists are still working to make more efficient types of coolants. In older A/C units made after the ban on chlorofluorocarbons, R12 and R22 refrigerant was used, although I'm not quite

sure what the numbers mean. In newer units, they started using R134a refrigerant. Finally, the newest things made in the past couple of years have used something called R410a refrigerant. I guess it is supposed to be more efficient, so that less of it needs to be used.
Post 2

I was never aware that common chemicals like ammonia where able to be used as refrigerants. What exactly are the chemical properties that make refrigerants able to absorb and disperse heat so well? Does anyone have any clue?

I always wonder what scientists will find is the problem with the current refrigerants that we use. At first, they were too dangerous to humans. Next, they were too dangerous to the ozone layer. I can only image that in a few more years they will find out that the stuff we are using today is responsible for something else.

What types of refrigerants are used today? I know I have heard of freon, but isn't that one of the older chlorofluorocarbons that was outlawed? Are scientists still working on products that may be safer for the environment?

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