Which of the following values represents absolute pressure for refrigerant R717?

Absolute pressure is a measure of pressure that is referenced to a perfect vacuum, while gauge pressure (psig) is referenced to atmospheric pressure. In the context of refrigerant R717 (ammonia), the absolute pressure is a critical parameter used in various calculations, including determining the refrigerant's properties and efficiency in a refrigeration system.

The value of 154.10 psia indicates the absolute pressure of R717, which is essential because it provides a clear understanding of the actual pressure being exerted by the refrigerant molecule within the system without the influence of atmospheric conditions. Understanding absolute pressure is vital, especially when analyzing phase changes, calculating efficiencies, or determining design specifications for refrigeration systems.

The other choices—psig, lbs./ft3, and kg/m3—do not represent absolute pressure. Psig refers to gauge pressure, which would not be applicable in this context since it does not account for atmospheric pressure. The other two options relate to density measurements, which provide insight into the refrigerant's mass per volume but do not relate to pressure measurements at all. Thus, the correct answer reflects a fundamental understanding of pressure types used in industrial refrigeration applications.