Commercial refrigeration systems use many types of pressure regulating valves. Examples are _______ pressure (two temperature valves), and crank case pressure controls.

• A. Condenser
• B. Suction
• C. Evaporator
• D. Discharge

Answer: (C)

In commercial refrigeration, controlling the pressure at the evaporator is a common way to set the evaporating temperature and precisely regulate how refrigerant enters the evaporator. A two-temperature valve is a form of evaporator pressure regulating valve, allowing two different evaporating temperatures by using two set points. Crankcase pressure controls, on the other hand, manage the pressure inside the compressor crankcase to protect lubrication and prevent liquid migration, which is a different part of the system than the evaporator. The other options refer to pressures in other parts of the system (high-side condenser pressure, suction, or discharge) and do not describe the two-temperature evaporator control. Therefore, the given example correctly points to evaporator pressure.