• SkillCat Team

Refrigerants Part 2

Updated: Apr 6

EPA 608 Core Chapter 5

Get your EPA 608 Certification for FREE

Ozone Depletion Potential (ODP)


In this module, we will define ozone depletion potential and how it is used to determine the harmfulness of different refrigerants. Skip to quiz!


Ozone Depletion


Recall from our Ozone module that ozone is a molecule found in our atmosphere. It absorbs and reflects harmful UV rays from the sun.


When released into the atmosphere, certain refrigerants are especially potent at destroying ozone. This is because the refrigerants contain chlorine.

CFCs and HCFCs are the most harmful because they contain chlorine. These refrigerants are also relatively stable, meaning they don’t get destroyed easily by rain or sunlight. This makes it more likely that they will reach the stratosphere, where the ozone layer is.


Refrigerant chemicals have a lifespan of 70-100 years — this is how long they will stay in the atmosphere, destroying ozone until they are broken down naturally.


ODP Number


We can characterize the potential of a refrigerant to destroy ozone as its Ozone Depletion Potential (ODP). The ODP number we assign to a refrigerant tells us how harmful that refrigerant is to ozone in the atmosphere.

CFCs are the most destructive to the ozone layer so its ODP is the highest. The next most destructive are HCFCs.


You can think of ODP as similar to the Richter scale, which describes the severity of earthquakes. On the Richter scale, the higher the number is, the larger the magnitude of the earthquake.


In terms of ODP, the higher that number is, the more harmful the refrigerant is for the ozone layer.


Highest ODP


ODP is a scale that determines how much ozone depleting potential substances have compared to each other.

Of all modern refrigerants, starting with CFCs, the highest ODP is 1. R-11 and R-12, which are both CFCs, both have an ODP of 1. All the HCFC, HFC, and newer refrigerants have an ODP of less than 1. This is because they are less harmful to the ozone layer than R-11 and R-12.


Note that there are older refrigerants that have an ODP of greater than 1. This means that they are more harmful to the ozone layer than R-11 and R-12. This includes halons, which were also used in fire extinguishers. These have long been banned.


ODP Comparison


Let’s look at the ODPs of several commonly used pure refrigerants. This chart shows the ozone depleting potentials of different examples of each type of refrigerants.


Notice that R-11 has the highest ODP of 1. R-11 is the most destructive refrigerant and we compare all other refrigerants against it. Note also that R-11 is a CFC, which we have already discussed is the most destructive refrigerant to ozone.

R-22, which is an HCFC, has an ozone depletion potential of 0.05. This means it still depletes the ozone layer but it is much less ozone depleting than CFC.


R-410a, which is an HFC refrigerant, has an ozone depletion potential of 0. R-1234yf, which is an HFO refrigerant, also has an ozone depletion potential of 0. As we discussed, this is because HFCs and HFOs do not contain chlorine so they do not deplete ozone.


Natural refrigerants, like nitrogen, carbon dioxide, and water, also have an ODP of 0 since they do not contain chlorine. Other natural refrigerants include hydrocarbons (HCs) such as propane (R-290) and isobutane (R-600a).


In this module, we defined ozone depletion potential. We also compared the ozone depletion potential of different refrigerants.



Global Warming Potential (GWP)


In this module, we will discuss the properties of different refrigerants. As we discussed in the previous module, certain refrigerants destroy the ozone layer. Other refrigerants can be harmful in other ways, which we will explore in this module. Skip to quiz!


Global Warming


Aside from potential to deplete the ozone layer, certain refrigerants also contribute to global warming. Let’s take a look at a short video to review the basics of global warming.


As discussed in the video, gases like carbon dioxide (CO2) naturally trap heat in the atmosphere. This makes Earth warm enough to be livable for us humans. We refer to these gases as greenhouse gases.


But an increase in these greenhouse gases traps more and more heat from the sun. This leads to a disruption in the balance of life on earth, leading to extreme weather events. Some gases are more potent at trapping heat in the atmosphere than others.


GWP Number

We measure how much a gas contributes to global warming with a number called the Global Warming Potential (GWP). This number is different for each gas. GWP measures how much energy one ton of gas will absorb over 100 years compared to carbon dioxide.


By definition, carbon dioxide has a GWP of 1 because it is the gas we use as a reference to compare other gases to. If the GWP of a substance is greater than 1, then it has a higher global warming potential than CO2.


The higher the GWP, the more heat the gas traps in the atmosphere. For example, if a gas has a GWP of 2, it means it will absorb two times as much energy as carbon dioxide over 100 years. If a gas has a GWP of 500, it means it will absorb five hundred times as much energy as carbon dioxide over 100 years.


GWP is a number that quantifies the effect of a chemical on the environment. It allows policymakers to compare and make decisions on what regulations are needed.


GWP Comparison


Let’s take a look at the global warming potentials of a few refrigerants. This table shows five different refrigerants. It includes their trade names and global warming potentials (GWPs).


Refrigerant Type ASHRAE Number GWP


CFC R-12 10900

HCFC R-22 1810

HFC R-410a 2088

HFO R-1234yf 4

HFO R-1234yf 3

Notice that R-12, a CFC refrigerant, has the highest GWP. R-12 has a GWP of 10,900, meaning it has a global warming potential of almost 11,000 times more than carbon dioxide.


We see here that R-410a, an HFC refrigerant, has a higher GWP than R-22, an HCFC refrigerant.


This is noteworthy because recall that HFCs were produced as an alternative to HCFCs. HFCs do not deplete ozone but they do contribute to global warming. This is why HFCs are also being phased out, as we discussed in Key Regulations.


Compared to all of the other refrigerants on this list, we see that the refrigerants with the least global warming potentials are:

  • R-1234yf, which is an HFO refrigerant

  • R-600a, which is an HC (hydrocarbon) refrigerant

This chart reflects the fact that the type of refrigerant corresponds to its global warming potential. In general, CFCs have the highest global warming potential. We see in this chart that the R-12 refrigerant has a GWP much larger than the others.


HFOs and HCs have the lowest global warming potential. Recall that HFOs and HCs were developed after CFCs, HCFCs, and HFCs. They were developed to provide an alternative to the high global warming potential of HFCs.


In this module, we discussed the characteristics of different types of refrigerants. Certain refrigerants deplete the ozone, others have high global warming potential. We also have to consider the different classes of safety of individual refrigerants in order to take proper safety precautions.



ASHRAE Safety Classification


In this module, we will discuss how the refrigerants are classified based on their flammability and toxicity. Skip to quiz!


Flammability and Toxicity Classes


ASHRAE is a global organization of engineers that establishes guidelines and standards in the HVAC industry. ASHRAE stands for American Society of Heating, Refrigeration, and Air Conditioning Engineers.


ASHRAE came up with a refrigerant safety classification system based on the flammability and toxicity of a refrigerant. This system is called Standard 34.This is the system that is used as a standard to understand the safety of different refrigerants.


Refrigerants are classified according to flammability and assigned to Class 1, 2, or 3.

  • Class 1 - Non-flammable refrigerants.

  • Class 2 - Low flammability refrigerants, and

  • Class 3 - High flammability refrigerants.

Refrigerants are also separated into two classes according to their toxicity.

  • Class A - Low-toxicity refrigerants

  • Class B - High-toxicity refrigerants


This table shows all the possible combinations of flammability classes and toxicity classes. We will go into more detail for this table after some quick comprehension questions.


2L Subclass


ASHRAE recently added a new subclass (2L) for flammability. This would be between Class 2 for low flammability and Class 1 for non-flammables.


Class 2L refrigerants have low flammability and a slow burn rate. The slow burn rate is what distinguishes Class 2L from Class 2.


Best and Worst

A1 refrigerants are the safest to use. We can see from this chart that A1 refrigerants are non-flammable and have low toxicity. This makes sense, since Class A refers to low toxicity and Class 1 refers to non flammable refrigerants.


B3 refrigerants are the most dangerous to use. These refrigerants are highly flammable and have high toxicity. This makes sense, since Class B refers to high toxicity and Class 3 refers to high flammability.







Discussing Refrigerants


Examples of A3 refrigerants include:

  • R-290 (propane)

  • R-600a (isobutane)

  • R-441a (hydrocarbon blend)

Notice that these are all hydrocarbons. Hydrocarbons generally have low toxicity because they are more natural but are also highly flammable.


Since hydrocarbons are highly flammable, we need to take extra precaution with them. We will discuss specific procedures in the Safety module.


A2L refrigerants include HFO refrigerants like R-1234yf. HFO refrigerants generally fall in the category of A2L refrigerants because they contain fluorine. Fluorine makes HFO refrigerants less flammable than hydrocarbon refrigerants, which are highly flammable.



B2 refrigerants include:

  • R-717 (Ammonia)

Ammonia is a natural refrigerant, as we previously discussed. But it has high toxicity, so it’s not ideal for every type of application.


Examples of A1 refrigerants include:

  • R-11 (CFC)

  • R-22 (HCFC)

  • R-410a (HFC)

This is why R-11 and R-22 were popular as refrigerants in the past — they are A1 refrigerants, which are the safest to use.


R-410a is a blend of two HFC refrigerants that was developed to replace the use of R-22, an HCFC. We will discuss more about refrigerant blends in the next module.


R-410a is also classified as a A1 refrigerant, meaning it is among the safest to use. While it is non toxic and non-flammable, it can cause asphyxia. This is the most important safety issue when it comes to R-410a.


The ASHRAE classification system provides an general understanding of how safe a refrigerant is. It also helps us understand why a refrigerant might be dangerous to use. This allows us to think of precautions to take with specific refrigerants, based on the dangers present.

For example, with a class B refrigerant, we know to take precautions around its high toxicity. With a class 3 refrigerant, we know to take precautions around its high flammability.


We will discuss specific handling procedures in the General Safety module.


In this module, we discussed how the ASHRAE organization classified different refrigerants based on their flammability and toxicity.



Question #1: The lowest number for an ozone depletion potential (ODP) is 1.

  1. True

  2. False

Scroll down for the answer...












Answer: False

The highest ODP is 1 for R-11, a CFC refrigerant. The potential of any refrigerant to deplete the ozone layer is compared to the ODP of R-11 and will be lower.


Question #2: Which type of refrigerants are most harmful to the ozone layer?

  1. HFOs

  2. UFOs

  3. HCFCs

  4. CFCs

Scroll down for the answer...












Answer: CFCs

CFCs have the highest ozone depletion potential of all the types of refrigerants because of the three chlorine atoms it contained.


Question #3: Which types of refrigerants are least harmful to the ozone layer? (Select all that apply)

  1. CFCs

  2. HCFCs

  3. HFCs

  4. HFOs

Scroll down for the answer...












Answer: HFCs

HFOs

HFCs and HFOs are non ozone depleting since they do not have chlorine atoms. They both have an ODP of 0. But CFCs and HCFCs, contain chlorine atoms. So they are the most ozone depleting.


Question #4: What is highest possible ODP for any CFC, HCFC, HFC, or HFO refrigerant?

  1. 0

  2. 1

  3. 100

  4. Infinite

Scroll down for the answer...












Answer: 1

The highest possible ODP for these refrigerants is 1 for R-11, a CFC refrigerant. The potential of any refrigerant to deplete the ozone layer is compared to the ODP of R-11 and will be lower.


Question #5: What is the least possible ODP for a refrigerant?

  1. 0

  2. 1

  3. 100

  4. None

Scroll down for the answer...












Answer: 0

The highest ODP is 1 for R-11, a CFC. If a refrigerant does not contain chlorine and does not destroy ozone, it has an ozone depletion potential (ODP) of 0.


Question #6: What is the ODP of R-600a?

  1. 1

  2. 0

  3. 0.5

  4. 0.25

Scroll down for the answer...












Answer: 0

R-600a is isobutane, which is a natural refrigerant. Since natural refrigerants do not contain chlorine, they do not deplete the ozone layer. So their ODP is 0.


Question #7: Which of the following refrigerants have an ODP of greater than 0?

  1. R-12

  2. R-22

  3. R-410a

  4. R-600a

Scroll down for the answer...












Answer: R-12

R-22

R-12 has an ODP of 1. It is a CFC refrigerant. R-22 has an ODP of 0.5. It is an HCFC refrigerant.


Question #8: What is the ODP of R-441a?

  1. 0

  2. 0.1

  3. 0.2

  4. 1

Scroll down for the answer...












Answer: 0

R-441a is a hydrocarbon refrigerant. Hydrocarbons are natural refrigerants and do not contain chlorine, they do not deplete the ozone layer. So all hydrocarbons have an ODP of 0.


Question #9: If a refrigerant has an ODP of 0.5, which of the following are true? (Select all that apply)

  1. It contains chlorine

  2. It might contain chlorine

  3. It could be R-22

  4. It could be R-1234yf

Scroll down for the answer...












Answer: It contains chlorine

It could be R-22

If a refrigerant has an ODP of anything greater than 0, it must contain chlorine, since it is chlorine that is responsible for destroying ozone. Examples of this include R-11, which has an ODP of 1 and R-22, which has an ODP of 0.5. They both contain chlorine.


Question #10: Which gas is used as a reference for measuring GWP?

  1. CFC

  2. HCFC

  3. Ozone

  4. Carbon Dioxide

Scroll down for the answer...









Answer: Carbon dioxide

Carbon dioxide is used as a reference in measuring global warming potential (GWP).


Question #11: GWP is a measure of how much energy a gas traps in the atmosphere over 100 years

  1. True

  2. False

Scroll down for the answer...












Answer: False

GWP is a measure of how much energy a gas traps in the atmosphere over a 100 years compared to carbon dioxide. GWP is not a measure of the amount of energy.


Question #12: Which of the following are true?

  1. Carbon dioxide has a GWP of 1

  2. Carbon dioxide has a GWP of 0

  3. Carbon dioxide has an ODP of 0

  4. Carbon dioxide has an ODP of 1

Scroll down for the answer...












Answer: Carbon dioxide has a GWP of 1.

Carbon dioxide has an ODP of 0.

Carbon dioxide has a GWP of 1. GWP is a comparison of how much energy a gas absorbs over a 100 years, compared to carbon dioxide.

Carbon dioxide has an ODP of 0. because it does not contain chlorine so it does not destroy ozone.


Question #13: If a gas has a GWP of 50, it means it has 50 times less global warming potential than carbon dioxide.

  1. True

  2. False

Scroll down for the answer...













Answer: False

A GWP of 50 means the gas has fifty times more global warming potential than carbon dioxide. It means that this gas will retain fifty times the amount of energy in the atmosphere as carbon dioxide over a hundred years.


Question #14: Of the following refrigerants, which one has the highest global warming potential (GWP)?

  1. R-12

  2. R-22

  3. R-410a

  4. R-1234yf

Scroll down for the answer...












Answer: R-12

As we saw in the chart earlier, the refrigerant with the highest global warming potential is R-12, which is a CFC refrigerant. It has a GWP of 10,900.

This means that it retains almost 11,000 times more than the amount of energy that carbon dioxide would trap in the atmosphere!


Question #15: Of the following refrigerants, which one has the least global warming potential (GWP)?

  1. R-12

  2. R-22

  3. R-410a

  4. R-1234yf

Scroll down for the answer...












Answer: R-1234yf

As we saw earlier with the chart, R-1234yf has the least GWP. It is an HFO refrigerant and has a GWP of only 4.


Question #16: R-12 has a GWP in which of the following ranges?

  1. 1-500

  2. 500-1000

  3. 1000-10,000

  4. 10,000-50,000

Scroll down for the answer...












Answer: 10,000-50,000

R-12 has a GWP of 10,900. This means it has close to 11,000 more global warming potential than carbon dioxide.10,900 would fall between 10,000 and 50,000.


Question #17: R-410a has a GWP in which of the following ranges?

  1. 1-500

  2. 500-1000

  3. 1000-10,000

  4. 10,000-50,000

Scroll down for the answer...












Answer: 1000-10,000

R-410a has a GWP of 2088, which means it has 2088 times more global warming potential than carbon dioxide. 2088 falls in between 1000 and 10,000.


Question #18: Which types of refrigerants have the lowest GWPs? (Select two)

  1. CFCs

  2. HFCs

  3. HFOs

  4. HCs

Scroll down for the answer...












Answer: HFOs

HCs

HFOs and HCs have the lowest GWPs.


Question #19: The GWPs of HFOs and HCs are close to those of HCFCs.

  1. True

  2. False

Scroll down for the answer...












Answer: False

False. The GWP of HFOs and HCs are in the single digits, while those of HCFCs are in the thousands.


Question #20: The GWP of R-290 is greater than which of the following? (Select all that apply)

  1. R-410a

  2. R-134a

  3. R-22

  4. None of these

Scroll down for the answer...












Answer: None of these

R-290 is greater than none of these refrigerants. Recall that R-290 is propane, which is a hydrocarbon. We mentioned that hydrocarbons, or HCs, have the lowest GWPs.

Answer choices 1, 2, and 3 are either HCFC or HFC refrigerants, which have GWPs in the thousands.


Question #21: Which class refers to a refrigerant with high toxicity?

  1. 1

  2. 3

  3. A

  4. B

Scroll down for the answer...











Answer: B

Refrigerants are separated into two classes of toxicity. Class A is low toxicity, while Class B is high toxicity. So the correct answer is B for high toxicity.


Question #22: Which class refers to a refrigerant with low toxicity?

  1. 1

  2. 3

  3. A

  4. B

Scroll down for the answer...











Answer: A

Class B is high toxicity as we said for the previous question, so class A is low toxicity.


Question #23: Which class refers to a refrigerant that has low flammability?

  1. 1

  2. 2

  3. 3

  4. A

Scroll down for the answer...












Answer: 2

The three classes for flammability are 1, 2, and 3. Class 2 is assigned to refrigerants with low flammability.


Question #24: Which class refers to a refrigerant that is not flammable at all?

  1. 1

  2. 2

  3. 3

  4. A

Scroll down for the answer...














Answer: 1

Class 1 is assigned to non-flammable refrigerants.


Question #25: What does the new subclass (2L) describe?

  1. Alternate highly flammable refrigerants

  2. Refrigerants that are Class 2 and burn slowly

  3. Refrigerants that are Class 2 and take longer to be effective

  4. Refrigerants that are toxic

Scroll down for the answer...