PSV relief sizing

This spreadsheet calculates the required effective discharge area of a pressure safety valve.

To calculate the required effective discharge area of a pressure safety valve, you'll need to know several key parameters, such as the relieving capacity (Q), the allowable overpressure, and the properties of the fluid being relieved. Here's a general equation that you can use to calculate the required effective discharge area (A):

A = (Q * Kd) / (C * P1 * (Kw * Kc * Kr))

Where:

A = Effective discharge area of the pressure safety valve (in square inches or square millimeters) Q = Relieving capacity (mass flow rate) of the valve (in lb/hr or kg/hr) Kd = Capacity correction factor for certified valves (dimensionless, usually provided by the manufacturer, typically around 0.975) C = Coefficient of discharge (dimensionless, usually provided by the manufacturer, typically around 0.61 for gas/vapor and 0.975 for liquid) P1 = Set pressure of the safety valve (in psi or kPa) Kw = Correction factor for backpressure (dimensionless, usually provided by the manufacturer or calculated) Kc = Correction factor for viscosity (dimensionless, usually provided by the manufacturer or calculated) Kr = Correction factor for the ratio of specific heats (dimensionless, calculated for gas/vapor services only)

Note that this equation is a general guideline, and the actual calculation can be more complex depending on the specific application and industry standards. It's important to consult relevant codes and standards (such as ASME or API) and work with a qualified engineer to ensure the accurate sizing of your pressure safety valve.