Relief Valve Sizing Analysis

Lili Lyddon

June 28, 2007

The Relief Valve Sizing Analysis in ProMax calculates the Effective Discharge Area, Relief Pressure, and other parameters. This analysis reports estimation of latent heat of vaporization for mixtures (Inlet Latent Heat parameter) which may be used for other applications. This sizing analysis applies only to relief devices intended to protect unfired pressure vessels against overpressure only. The pressure relief devices do not protect against structural failure when the vessel is exposed to extremely high temperatures such as during a fire. The Analysis is based on recommended practices for sizing of relief valves as laid out in several published international standards. These methods are a guide for selection of pressure relief devices for equipment with maximum working pressures exceeding two atmospheres (absolute). Selection of valves from manufacturer data sheets is made via the effective discharge area calculated by this analysis. A valve with an effective area close to but exceeding this value is recommended. The implemented standards suggest final selection be made in consultation with your relief valve manufacturer.

Authored by Lili Lyddon (BR&E Technical Support and Help Author)