Vacuum Relief Valve
A vacuum-relief valve (Figure 15-37) is an effective means of providing protection against the buildup of excessive vacuum conditions in steam heating and steam processing systems. It is also used in combination with temperature-pressure relief valves on water heaters.
Vacuum conditions can often occur after the supply line has been shut off. Steam condenses, and a vacuum can be created that not only affects system operation but also can cause damage to equip- ment. The vacuum relief valve automatically admits air to the system in order to break up the vacuum. These valves operate
under conditions up to a maximum temperature of 250°F. The valve disk should be constructed from a material capable of with- standing high temperatures, particularly when the valve is used in a steam processing system.
