Refrigerants Part 1
- SkillCat Team
- Sep 16
- 6 min read
EPA 608 Core Chapter 5
Introduction to Refrigerants
In this module, we will define refrigerant and also discuss different types of refrigerants.
What are Refrigerants?
Have you ever wondered how your refrigerator keeps your favorite ice cream cold?
Recall from our Refrigeration Cycle module that refrigerant absorbs heat from hot indoor air and transfers it outdoors. This is how air conditioning units provide cooling.
This is also how your fridge keeps your favorite ice cream cold. Your refrigerator makes use of the refrigeration cycle to transfer heat from the inside of your fridge to the outside. And the key to making this happen is the refrigerant.
A refrigerant is a substance or mixture that absorbs heat by using it to boil, changing phase from liquid to vapor.
We can choose from any number of substances to use as a refrigerant. Good refrigerants are cheap and have a low boiling point. Low boiling points are necessary because we need the refrigerant to boil at room temperature. Recall that boiling is what provides cooling.
But as we discussed in the Ozone module, some refrigerants are harmful to the environment. Some refrigerants are also more flammable or toxic than others.
That is why it is important to look at the properties of different refrigerants. We need to consider their effect on the environment as well as how safe they are.
Types of Refrigerants
CFCs were widely used in the mid 1900s before it was discovered that they were depleting the ozone layer. As we discussed in Key Regulations, these refrigerants were the first to be phased out.
We say pure refrigerants to distinguish from refrigerant blends, which consists of multiple refrigerants. Pure refrigerants are one substance only. We will discuss blends in a later module.
There are five major categories of pure refrigerants that we will cover for the EPA exam:
- CFCs
- HCFCs
- HFCs
- HFOs
- Natural refrigerants
CFCs and HFCs are categories of refrigerants. This means there are multiple refrigerants that are CFCs or HFCs. Think of a category of refrigerants as a color. If something is blue, it could be sky blue or ultramarine or indigo.
If a refrigerant is a CFC, it could be any number of specific refrigerants. It could be R-11, R-12, et cetera. The list goes on. To reiterate, CFCs are a category of refrigerants, not one specific refrigerant.
In this module, we defined refrigerants and their types.
In the next module, we will delve further into CFCs and HFCs.
CFCs and HCFCs
In this module, we will discuss the first two types of refrigerants -- CFCs and HCFCs.
Categories of Refrigerants
There are five major categories of pure refrigerants that we will cover for the EPA exam:
- CFCs
- HCFCs
- HFCs
- HFOs
- Natural refrigerants
In this module, we will discuss the first two -- CFCs and HCFCs.
CFC Refrigerants
CFCs are a category of refrigerants called chlorofluorocarbons. R-11 and R-12 are examples of CFC refrigerants.
CFCs are made of:
- Chlorine
- Fluorine
- Carbon
HCFC Refrigerants
HCFCs are made of:
- Hydrogen
- Chlorine
- Fluorine
- Carbon
HCFCs are a category of refrigerants called hydrochlorofluorocarbons. R-22, R-123, and R-124 are examples of HCFC refrigerants.
HCFCs were developed as a transitional alternative to CFCs. Although not as harmful as CFCs, HCFCs still have chlorine so they still destroy ozone in the atmosphere.
HCFCs have mostly been phased out in developed countries. This means that it is illegal to have new production or import of HCFCs. But HCFCs are still used in existing refrigeration equipment. The most common of HCFCs we still see today is R-22. This is seen in servicing systems that still operate on R-22.
In this module, we discussed the historic use of different refrigerants and certain refrigerants (CFCs and HCFCs) were harmful to the ozone layer. In response to this, new refrigerants were developed that do not contain chlorine. Because they do not contain chlorine, they do not harm the ozone layer.
In the next module, we will discuss the characteristics of these refrigerants in further detail.
HFCs, HFOs, and Natural Refrigerants
In this module, we will delve further into different types of non-ozone depleting refrigerants.
HFC Refrigerants
HFCs were developed as an alternative to CFCs and HCFCs. It was effective as a refrigerant and did not contain chlorine, so it did not destroy ozone.
But it turned out that while HFCs do not deplete the ozone layer, they contribute to global warming. We will go into specifics of global warming later in this module.
HFCs are a category of refrigerants called hydrofluorocarbons. R-32, R-125, and R134a are all examples of HFC refrigerants.
HFCs are made of
- Hydrogen
- Fluorine
- Carbon
HFO Refrigerants
As we discussed in Key Regulations, CFCs have been phased out, and HCFCs will soon be phased out. HFCs are also in the process of being phased out because of their high global warming potential.
Then there’s HFOs, which are a new class of refrigerants. HFOs have much lower global warming potential than HFCs.
HFOs are a category of refrigerants called hydrofluoroolefins. The HFO refrigerant we see most commonly is R-1234yf.
HFOs are composed of:
- Hydrogen
- Fluorine
- Carbon
Notice that the elements that HFOs are made of do not directly correspond to the letters in its name, like it has with other refrigerants. Notice also, that HFOs have the same elements as HFCs.
With HFOs, we have to beware that they are not compatible with silicone. Silicone elastomers are used in seals and gaskets in refrigeration systems. But in the presence of HFOs, silicone elastomers swell, so this affects how the system behaves.
Notice that HFOs do not contain chlorine, so they do not destroy ozone. Compared to HFCs, they are not as harmful in contributing to global warming.
Natural Refrigerants
Different types of refrigerants were developed in order to provide an alternative to the ozone depleting and global warming refrigerants. These alternatives to traditional refrigerants are called natural refrigerants.
These alternatives are called natural refrigerants because they can be found in nature and are generally much more environmentally friendly than past refrigerants.
Examples of natural refrigerants include:
- HCs, or hydrocarbons
- Carbon dioxide
- Ammonia
Examples of hydrocarbons are:
- Propane, which is known as either R-290, or HC-290
- Isobutane, which is known as either R-600a, or HC-600a
Note that propane is used for grilling, because it is highly flammable, so it is great for starting a fire. However, the propane used for grilling cannot be used to charge refrigeration systems.
Propane cylinders used for grilling are not rated for refrigerant use. This is because these propane cylinders contain impurities that can damage refrigeration equipment. Propane used for refrigeration purposes will be labeled R-290.
Carbon dioxide can also be used as a refrigerant. As a refrigerant, it is known as R-744.
Ammonia as a refrigerant is known as R-717. It has been used since the 1850s for cooling purposes. We see ammonia today mostly in commercial applications.
In this module, we discussed the non-ozone depleting refrigerants which were developed as an alternative to CFCs and HCFCs, as they were harmful to the ozone layer.
Refrigerant Naming
In this module, we will discuss different naming conventions for the refrigerants.
Refrigerant Naming
To wrap up this discussion on different types of refrigerants, let’s go over some alternative naming conventions for the refrigerants we just looked at.
Refrigerants may be named by a combination of “R” and a number, where the letter R refers to the fact that this chemical is a refrigerant.
This naming convention was developed by ASHRAE, so this number can also be called a refrigerant’s ASHRAE number. ASHRAE is a global organization of engineers that establishes guidelines and standards in the HVAC industry.
For example, R-12 is the name of a refrigerant using its ASHRAE number. As we discussed in this module, R-12 is a CFC.
R-12 is the same as CFC-12. They are two ways of referring to the same refrigerant. As long as the number part is the same, it is the same refrigerant.
To avoid confusion, there is no HCFC-12 or HFC-12. So when we say R-12, there’s only one refrigerant it could be, and that is CFC-12.
To reiterate, the following refrigerants are the same:
R-12 is the same as CFC-12
R-22 is the same as HCFC-22
R-134a is the same as HFC-134a
R-1234yf is the same as HFO-1234yf
In this module, we identified the different trade names and naming conventions for each type of refrigerant. For example, CFC-11 is the same refrigerant as R-11. They are both trade names for the same CFC refrigerant.
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