What must be the differential setting of a pressure control adjusted to cut-in at 40 psig and cut-out at 15 psig?

The differential setting of a pressure control is calculated by finding the difference between the cut-in pressure and the cut-out pressure. In this scenario, the cut-in pressure is 40 psig, and the cut-out pressure is 15 psig. To find the differential, you subtract the cut-out pressure from the cut-in pressure:

40 psig (cut-in) - 15 psig (cut-out) = 25 psig.

Therefore, the required differential setting is 25 psig, making it the correct choice. This setting ensures that the refrigeration system operates efficiently by maintaining the proper pressure range for optimal cooling performance.