EPA Section 608 — Core
Substitutes and oils: practice questions
Our EPA 608 Core bank has 7 questions on this topic. Here are 4 of them with answers; the full mock exam draws from every topic, like the real one.
Question 1
What is a drawback of POE oil?
- It freezes at 50 °F
- It is flammable at room temperature and must be stored in a fireproof cabinet
- It cannot be used with HFCs
- It is very hygroscopic: it absorbs moisture readily
Show the answer
D. It is very hygroscopic: it absorbs moisture readily — Keep POE oil containers sealed and minimise exposure to air.
Question 2
What should a technician do before charging a system with a substitute refrigerant?
- Check compatibility, including oils, seals and components
- Mix it with the old refrigerant
- Vent the old oil
- Use any available oil
Show the answer
A. Check compatibility, including oils, seals and components — Substitutes are rarely drop-in replacements.
Question 3
Can different refrigerants be mixed in a system or recovery cylinder?
- Yes, if the pressures are similar
- No
- Yes, in a recovery cylinder
- Yes, if they are both HFCs
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B. No — Mixed refrigerants may be impossible to reclaim and must be destroyed.
Question 4
Why should a zeotropic blend be charged as a liquid?
- Because a zeotropic blend cannot exist as a vapor at room temperature
- Because it is flammable as a vapor
- To heat the cylinder
- To prevent fractionation (changing composition)
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D. To prevent fractionation (changing composition) — Fractionation happens when blend components leak or vaporise at different rates.