PRV Sizing Calculator uses the equations described in API 510, and allows the user to size a pressure relief valve intended for gas/vapour, steam or liquid duty.
The calculator offers the user the choice of two unit sets; SI (kg/hr, kPa(a/g), degrees Kelvin) and USC (lb/hr, psi(a/g), degrees Rankine (note the user will need to convert from degrees Centigrade (C + 273.15 = K) and Fahrenheit (F + 460.0 = R) respectively).
Note on the vapour and steam calculation sheets that only the mass relief rate can be input, or calculated); the volumetric flow rate cannot be used as a parameter. This has been done deliberately to minimise user error.
When the calculator is configured to run in Calculate Area mode, the API relief valve size will be displayed; this will be a letter designation from D to T.