Valves used in Pipelines - SAFETY RELIEF VALVES PDF Print E-mail
Written by Norrie   
Sunday, 02 May 2010 18:18
Article Index
Valves used in Pipelines
TYPES OF VALVES - GATE VALVE
TYPES OF VALVES - THE GLOBE VALVE
TYPES OF VALVES - NEEDLE, ANGLE, PLUG, BALL, BUTTERFLY, CHECK VALVE
SAFETY RELIEF VALVES
VALVE ACCESSORIES
VALVE OPERATORS
All Pages

8. SAFETY RELIEF VALVES (See Figure : 21)

Safety valves are installed on equipment to prevent over-pressure (or excess vacuum), which could cause damage, rupture or collapse of the equipment.

Where the type installed is to prevent excess vacuum, they are normally referred to as 'Vacuum Breakers'.

A safety valve will have a lifting set pressure higher (about 1.5 times) than the operating pressure of the system but well below the design maximum pressure allowed.

In the conventional type, the pressure of the valve discharge line will affect the set pressure of the valve by giving a back-pressure on the valve plug.

In the bellows type, the bellows isolates the plug from the back-pressure and therefore there is no effect on the valve setting.

The following diagram is of a conventional safety relief valve. All safety valves have the same purpose of protecting equipment from over-pressure. Different makers have their own designs.

SAFETY RELIEF VALVE

Figure : 21