Type III — Low-PressureQuestion 173 of 240
Approximately what inches-of-mercury vacuum reading corresponds to the 25 mm Hg absolute recovery level for low-pressure appliances?
a.About 29 inches Hg vacuum
b.About 15 inches Hg vacuum
c.About 10 inches Hg vacuum
d.About 4 inches Hg vacuum
Explanation
25 mm Hg absolute is a deep vacuum equal to roughly 29 inches of mercury vacuum on a compound gauge, since atmospheric pressure is about 760 mm Hg or 30 inches Hg. This is far deeper than the 4 to 15 inches used for high-pressure systems. It reflects how completely a low-pressure chiller must be evacuated.
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