• SkillCat Team


Updated: Feb 24

EPA 608 Core Chapter 36 (Take full course for free)

In this module, we will go over the details of recharging the refrigerant and, we will also discuss the precautions to take while servicing the equipment.

1. Flammable Refrigerants

When working with flammable refrigerants, we need to take a few additional precautions before recharging the system. This is because flammable refrigerants can cause explosions and injuries if not handled properly.

Recall that flammable refrigerants include hydrocarbons and HFOs. Hydrocarbons are generally highly flammable, or Class 3 according to ASHRAE classification. HFO-1234yf is mildly flammable, at Class 2L.

For all hydrocarbons, we need to complete the following before recharging:

  • Electrically ground the system

  • Install a fresh filter-drier

  • Complete a standing-pressure leak check at the maximum system pressure

  • Evacuate to 500 microns or lower

We need to ground the system before recharging flammable refrigerants. This is to reduce the chance of electrical fires while working with flammable refrigerants.

We have to install a fresh filter drier with flammable refrigerants. Filter driers absorb contaminants and installing a fresh one reduces the chances of flammable refrigerants reacting with contaminants.

We also need to perform a standing pressure leak check at the maximum system pressure. Leaks with flammable refrigerants can cause fires or explosions. So we need to make sure the system is not leaking, even at its highest pressure.

And lastly, before recharging with flammable refrigerants, we need to evacuate to 500 microns or less. This ensures that there are basically no contaminants in the system that the flammable refrigerant can react with.

All of these steps need to be taken in order to make sure the flammable refrigerant does not cause an explosion.

2. Completing Service

During servicing, liquid refrigerant can get trapped in the service hose between closed service valves. This happens when you transfer refrigerant between the system and a recovery unit.

It’s like using a straw. Imagine sipping soda through a straw. When you are done with your sip, there is still soda in the straw. What happens to the soda in the straw? Well when you let go of the straw, the soda falls back into the can. This is backwash.

The same thing happens with refrigerant. You can think of the service hose as a straw.

We want to make sure we don’t trap any liquid refrigerant in the service hose. Any refrigerant trapped in the service hose will be vented when you disconnect it. And recall, it is illegal under Section 608 to vent refrigerants that deplete ozone (CFCs, HCFCs, and their substitutes).

3. Conclusion

In this module, we discussed the recharging techniques and procedures used while servicing the equipment.

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