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Engineering ToolBox > Liquid System Safety Valves - Spring Operated

The minimum discharge area of spring operated relief safety valves in liquid systems can be calculated as
A = q SG1/2 / (28.14 Kbp Kvisc dp1/2)
where
A = discharge area (Square Inches)
q = relieving capacity (Gallons per Minute)
SG = Specific Gravity
Kbp = capacity correction for back pressure - 1.0 for atmospheric pressure systems
Kvisc = correction factor due to velocity - 1.0 for most water systems
dp = differential pressure - set pressure (psig) + over pressure (psig) - back pressure (psig)