The low-pressure cutout switch settings vary with the refrigerant used and the temperature application. If the low-pressure cutout switch for a particular application is set with a cut-in pressure of 5 psig, what would be the cut-out pressure if the differential is 7.5 psig?

Correct Answer: Option A — 5" Hg

Subtracting the 7.5 psig differential from the 5 psig cut-in pressure results in a cut-out pressure of -2.5 psig. Converted to vacuum units using standard atmospheric equivalents, this equates to approximately 5 inches of mercury (5" Hg) vacuum.