SAFETY VALVE

A valve which automatically discharges fluid to prevent a pre-determined safe pressure being exceeded. It is generally used for compressible fluids such as steam and other gases which demand quick over-pressure relief.

TYPES OF SAFETY VALVE

Ordinary safety valve    

A valve in which the disk lifts automatically at least D/24, where 24 = bore of valve seat.

The valves may be:

a.  Direct  spring loaded                

In which the load is applied directly to the disk by a spring.

b.  Lever and weight loaded       

In which the load is applied to the disk by a weight acting through a lever and fulcrum.

High lift safety valve      

A safety valve in which the disk lifts automatically at least D/12,

(where D = bore of valve seat.)

Full lift safety valve        

A safety valve in which the disk lifts automatically a distance giving, when the disk is fully lifted, a discharge area round the edge of the valve seat equal to the area through the seat orifice after deducting the area of guides or other obstructions.