Pressure Relief - Direct - Low Pressure

Pressure Relief Valves - Low Pressure - Direct Acting.

The direct acting relief valve is designed to release system over pressures exceeding an adjustable 0.2 through to 1.5 bar setting quickly and effectively so that upstream equipment is not damaged by system over pressure caused by pump start up, shut down and actuated valve closure elsewhere upstream in the system. Direct acting low pressure safety relief valves are designed to work on lower pressure systems from 0.2 bar to 1.5 bar and can be manually adjusted to automatically release at a manually pre-set pressure anywhere between 0.2 and 1.5 bar.

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For example if a pressure relief valve is set to activate or release at 1 bar the low pressure safety relief valve will stay closed until the back pressure or upstream system pressure reaches close to 1 bar, at which time the safety relief valve will quickly open releasing pressure downstream and will slowly close once pressure has dropped below safe limits. The low pressure safety relief valve is designed with a much larger diaphragm allowing for high sensitivity ideally suited to low pressure ranges, the larger control diaphragms which are based on applied pressure to area formulae i.e. the more surface area exposed to pressure the more force generated which is ideal for low pressure control as there is more surface area. As the diaphragm is circular in construction the surface area A is equal to the radius R multiplied by Pi π (=22/7) squared² or A= π x r² so for any single unit of radius increase the surface area increases 10 fold giving a 10 fold force or sensitivity increase.

Low pressure direct acting relief valves are available in a range of materials however the material price increases seen since 2008 have pushed brass and bronze prices very close to stainless steel, so many prudent direct acting pressure relief valve manufacturers are now producing in only stainless steel, thus reducing manufacturing costs and offering a single durable hard wearing chemically corrosion resistant pressure relief valve. The RELT (Threaded) and RELF (flanged) low pressure relief valves are made entirely from 316 Stainless steel and are suitable for fluids, air, gas's and oil. 

Pressure Adjusting Range: 0.2 Bar to 1.5 Bar.

Test Pressure: 16 Bar

Temperature Range: -15°C to +80°C

Pressure Required fully open is 0.3 Bar