A Silent Safety Valve is a valve that works as a fail – safe, the ideal example of which is a Pressure Relief Valve. A Silent Safety Valve automatically releases a substance i.e., fluid, stem or gas as the case may be from a boiler, pressure vessel or other system, as the pressure or temperature exceeds a predetermined limit. Safety Valves are basically used with compressible gases, i.e., steam and air services. The classification of Silent Valves can be done in accordance to the lift of disk and bore of the valve.
Difference between Silent Safety Valve and Relief Valve:
A Safety Valve is a relief device on a compressible filled vessel. Safety Valve fully opens, once the preset pressure level is reached. While, a Relief Valve, releases the pressure just to prevent an over pressure condition.
The Working of Silent Safety Valve:
The Safety Valve is tailor made or set to open at a pre – fixed set pressure. The purpose is to protect pressure vessels and other equipment’s from subjected to pressure that exceeds their capacity. Technically speaking, the safety valve releases the excessive pressure i.e., the pressure beyond the pre – set limit and allows the excessive pressure to flow out of the system through an auxiliary passage. From the working of the Safety Valve we can also conclude that the basic function of Silent Safety Valve is to protect life, property as well as environment.
The Use of Two Silent Safety Valves for Boiler:
Generally there is a use of two Safety Valves for Boiler because sometimes due to spring failure or because of condensation of steam on the upper side of safety valves, the lifting pressure increases. Therefore, for high pressure Boiler, two safety valves are fixed on its steam drum.