The low-pressure cut-out switch settings vary with the refrigerant used and the temperature application. If the low-pressure cut-out 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?
ā¢ Relationship between cut-in pressure, cut-out pressure, and differential in a pressure control ā¢ Understanding that a positive differential is the difference between cut-in and cut-out, not an added operating pressure ā¢ Unit awareness: psig vs inches of mercury vacuum (" Hg vac.)
ā¢ How is differential defined in a pressure switch: is it cut-in minus cut-out, or cut-out minus cut-in for this type of control? ā¢ If the system restarts (cuts in) at 5 psig and the differential is 7.5 psig, in which direction must the pressure have moved while the compressor was running? ā¢ Sketch a simple number line with pressure values and mark the cut-in point, then move by the amount of the differential to find the cut-out point.
ā¢ Be clear on whether cut-out pressure = cut-in pressure Ā± differential for low-pressure controls on refrigeration systems. ā¢ Check that the resulting pressure sign (positive/negative) and units make sense for a low-pressure cut-out in this context. ā¢ Eliminate any choice that does not match the numerical difference of 7.5 psig from the given 5 psig cut-in pressure.
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