EPA 608 Core Chapter 42 (Take full course for free)
This module will look at the different techniques that need to follow while handling flammable refrigerants.
1. Brief Review: Flammable Classes
Recall that there are three flammability classes: 1, 2 and 3. The flam
mable classes are 2 and 3, with 2 being low flammability, and 3 being high flammability.
Examples of A3 refrigerants (low toxicity, high flammability) are hydrocarbons. This includes propane (R-290) and isobutane (R-600a).
2. Equipment Color Markings
If a refrigerant is flammable, there are special requirements for the equipment that it is used in. This includes refrigerants in class 2 (low flammability) and class 3 (high flammability).
If flammable refrigerant is used, the process tubes and piping that it passes through have to be marked red. Any places where there is a service connection to the flammable refrigerant also have to be marked red.
These places are marked red so that technicians can take precautions when handling those areas of equipment.
The red marking must extend at least one inch in both directions for all process tubes, pipes, and service connections with flammable refrigerants.
So as an example, all process tubes, pipes and service connections for propane (R-290) and isobutane (R-600a) will need to be marked red, with a minimum of one inch in both directions.
3. Grounding
When recovering any flammable refrigerant, you have to make sure that your equipment is grounded.
Your equipment uses electricity and we want to minimize the possibility of any charge interacting with the flammable refrigerant. Grounding your equipment will reduce the risk of electrical fires.
4. Flammability Limits
With flammable refrigerants, we have to consider their
Lower Flammability Limit, and
Upper Flammability Limit
The Lower Flammability Limit is the lowest concentration of a refrigerant that will cause the refrigerant to sustain a flame.
This is because the refrigerant molecules are spread too thin for the fire to continue to burn through. If the amount of the refrigerant in the air is less than this limit, the refrigerant will not sustain a flame.
The Upper Flammability Limit is the highest concentration of a refrigerant that will cause the refrigerant to sustain a flame. This may be counterintuitive. How can there be too much refrigerant if it is flammable?
Recall that burning requires oxygen. If there are too many refrigerant molecules, there will not be enough oxygen for all the refrigerant molecules to burn.
But if the concentration is higher than the Lower Flammability Limit and lower than the Upper Flammability Limit, then the refrigerant can burn or explode.
If the concentration is higher than the Lower Flammability Limit and lower than the Upper Flammability Limit, then the refrigerant can burn or explode. But even so, a flame source is still needed for the refrigerant to burn or explode.
For example, we know that hydrocarbons are highly flammable. If there is a sufficient concentration of hydrocarbon refrigerant in a space, and there is an ignition source, this will likely lead to an explosion.
That is why it is important that technicians do not use flames near refrigerant cylinders.
To reiterate, if you are using flammable refrigerants, do not:
Apply an open flame or steam to a refrigerant cylinder
Cut or weld any refrigerant line when refrigerant is in the unit
These can provide the ignition source that the refrigerant needs to burn or explode.
5. Conclusion
In this module, we discussed the various safety procedures to be followed while handling flammable refrigerants.
Next, we will discuss specific procedures and things to be aware of when handling refrigerant cylinders.