Relief valves are typically used for service with?

Relief valves are designed to protect pressurized systems by releasing excess pressure, thereby preventing potential hazards such as equipment failure or explosions. While relief valves can be utilized in various applications, they are typically used in service with liquids due to the nature of how liquid pressure is managed in plumbing and piping systems.

In liquid applications, relief valves are essential for maintaining safe operating conditions. When pressure within a liquid system exceeds the set threshold, the relief valve opens and allows the liquid to escape, thus reducing the pressure back to safe levels. This is particularly important in systems like water supply, hydronic heating, or any application where liquids are under pressure.

In contrast, while relief valves can also be used with gases, vapors, and steam, the challenges associated with these mediums, including the varying compressibility and behavior under pressure, often require specialized types of relief devices or additional considerations in system design. Therefore, the primary and most common application of relief valves is in liquid systems, making it the most appropriate answer in this context.