A They can be either manually closed or automatically closed when disconnected to prevent loss of refrigerant from hoses What is the strongest evidence that HCFCs are in the stratosphere? B Measurement of chlorine in air samples from the lower atmosphere. Which of the following will help allow you to size smaller cooling systems?
The secondary refrigerant acts to a undergo the refrigeration cycle b protect the ozone depletion c carry the heat within refrigerated space d cool the Create an Account and Get the Solution. Log into your existing Transtutors account. Have an account already? Click here to Login. No Account Yet? Click here to Sign Up. Sign in with Facebook. Looking for Something Else? We don't collect information from our users. Only emails and answers are saved in our archive. Cookies are only used in the browser to improve user experience.
Some of our calculators and applications let you save application data to your local computer. These applications will - due to browser restrictions - send data between your browser and our server. We don't save this data. 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 refrigerant has a GWP much larger than the others. HFOs and HCs have the lowest global warming potential. 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 came up with a refrigerant safety classification system based on the flammability and toxicity of a refrigerant. This system is called Standard 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. 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.
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. 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.
Examples of A3 refrigerants include:. 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. 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:. Ammonia is a natural refrigerant, as we previously discussed.
Examples of A1 refrigerants include:. This is why R and R were popular as refrigerants in the past — they are A1 refrigerants, which are the safest to use.
We will discuss more about refrigerant blends in the next module. Ra 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 Ra. 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. Scroll down for the answer Answer: False. The potential of any refrigerant to deplete the ozone layer is compared to the ODP of R and will be lower.
Question 2: Which type of refrigerants are most harmful to the ozone layer? 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. Answer: HFCs.
They both have an ODP of 0. So they are the most ozone depleting. Answer: 1. Question 5: What is the least possible ODP for a refrigerant? Answer: 0. If a refrigerant does not contain chlorine and does not destroy ozone, it has an ozone depletion potential ODP of 0. Ra 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? Answer: R R has an ODP of 1. It is a CFC refrigerant. R has an ODP of 0. It is an HCFC refrigerant. Ra 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.
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