What is the function of a pressure relief valve?

A pressure relief valve's primary function is to automatically release excess pressure in a system. This is crucial for maintaining safety and preventing damage to pipes and equipment due to pressure surges. When system pressure rises above a predetermined limit, the valve opens, allowing fluid to escape, which helps to reduce pressure to a safe level.

The design of pressure relief valves ensures that they react promptly to prevent overpressure conditions, hence protecting the integrity of the system and ensuring safe operation. This automatic feature is vital in various applications, including plumbing, industrial processes, and other systems where pressure control is essential.

In the context of the other choices, increasing system pressure, maintaining constant pressure, and restricting fluid flow do not align with the primary purpose of a pressure relief valve, which is solely focused on managing excess pressure to prevent potentially hazardous situations.