Which of the following terms refers to the pressure measurement for refrigerant R717 (Ammonia) when using a gauge?

The term that refers specifically to the pressure measurement for refrigerant R717 (Ammonia) when using a gauge is psig, which stands for pounds per square inch gauge. This unit of pressure measurement is commonly used in various industrial applications, particularly in refrigeration systems.

Psig measures the pressure relative to atmospheric pressure, meaning it indicates how much pressure is exerted by a system above the atmospheric level. When you are working with refrigeration systems, including those that involve R717, it is important to know the pressure within the system without the influence of atmospheric pressure, as this helps in accurately assessing the operating conditions and ensuring safe and efficient system performance.

While psia (pounds per square inch absolute) is another relevant measure that includes atmospheric pressure in the calculation, psig is generally more useful in practical applications for gauge readings. Pascals and bar are also pressure units but are not as commonly used in refrigeration systems for reporting pressure directly on gauges for R717.