What should be done first to prevent cross-contamination?

Recovery techniques · EPA 608 Type II. The correct answer, and the reasoning behind it.

Recovering liquid first, speeding recovery, and avoiding cross-contamination.

The question

A technician has finished recovering R-22 and next needs to recover R-410A with the same machine. What should be done first to prevent cross-contamination?

• ARun the machine on R-410A for a minute, then vent the hoses to air
• BUse the same recovery cylinder for both refrigerants
• CAdd a small amount of POE oil to the machine
• DClear the R-22 from the machine and hoses as the manual directsCorrect answer

Why “Clear the R-22 from the machine and hoses as the manual directs” is correct

Refrigerant left in the machine, hoses and filter would mix with the next refrigerant. Clearing it out according to the manufacturer's procedure keeps the next batch clean and avoids releasing refrigerant, as 82.156(g) requires equipment to be used per the manufacturer's directions.

Source: EPA: Test Topics; 40 CFR 82.156(g)

Why the other answers are wrong

• Run the machine on R-410A for a minute, then vent the hoses to air — Venting hoses releases refrigerant and is prohibited.
• Use the same recovery cylinder for both refrigerants — Sharing a cylinder mixes the two refrigerants.
• Add a small amount of POE oil to the machine — Adding oil does nothing to remove leftover R-22.

Practice more of this

More EPA 608 Type II practice questions, or see every EPA 608 practice test.