What does a relief valve do in a refrigeration system?

A relief valve is a critical safety component in a refrigeration system, designed to protect the system from excessive pressure. When the pressure inside the system exceeds a predetermined safe level, the relief valve opens to release the excess pressure, thereby preventing potential damage or failure of the refrigeration equipment. This function is essential in maintaining the integrity of the system, ensuring it operates within safe parameters.

The other choices do not accurately describe the role of a relief valve. While increasing system pressure, maintaining flow, and regulating evaporator operation are important functions in a refrigeration system, they pertain to different components and systems, such as compressors or expansion devices. The primary and distinctive role of the relief valve is specifically related to pressure relief, which is why the correct answer focuses on its function in overpressure situations.