Type II — High-PressureQuestion 155 of 240
A technician is selecting a vacuum pump to properly dehydrate a Type II R-410A system. Why is a dedicated vacuum pump used instead of the recovery machine to pull the final vacuum?
a.Recovery machines pull a deeper vacuum than any vacuum pump
b.Vacuum pumps are only for low-pressure chillers
c.A vacuum pump can reach the deep vacuum (down to hundreds of microns) needed to boil off moisture, which a recovery machine is not designed to do
d.Using a vacuum pump lets the technician vent refrigerant safely
Explanation
A vacuum pump is designed to reach the deep vacuum, often several hundred microns, required to boil moisture out of the system, while a recovery machine is built to move refrigerant, not to achieve that deep dehydration vacuum. Reaching a low, stable micron level ensures moisture and noncondensables are removed. A vacuum pump is never used to vent refrigerant.
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