Just like your heart has valves to regulate the flow of blood from one section to another, a valve in a mechanical system is placed at strategic points to release pressure and allow the flow of fluid or air from one section to another.
A safety valve is used to regulate steam in a closed system. When the steam pressure reaches a set point, the valve opens and releases the vapor into the atmosphere or open area. For instance, fast-acting safety valves are used in boiling water nuclear reactors to maintain the safety of the reactor vessel. Failure of a valve to open could cause an explosion, such as occurred in 2005 at a BP Texas Oil Refinery. This tragedy was partly caused by a safety valve that failed to open. More ordinary usage of the kunkle safety valve is for tanks, pumps, and hydraulic systems.
A relief valve is used to regulate the flow of liquid in a closed system. The valve opens incrementally, releasing a little bit of pressure at a time. Instead of venting the extra fluid into the atmosphere, the liquid is sent back down the same system to a point with less pressure. Because of the closed system, pressure can be maintained, and the fluid is sent to be reused.
Advantages and Disadvantages
For valves to work, they must be properly fitted to the machine in which they are placed. Plus, they are very versatile. Relief valves, though, can have problems if the back pressure is too high.
Engineers place valves at critical points in a system where pressure release is needed
to prevent a potential disaster. The type of valve needed depends on if steam needs to be vented and released or liquid needs to be rerouted to reduce pressure. Knowing which valve is correct for your application is critical for proper usage.