Air Tests of Commercially Available Transport Vessel PRVs

Abstract

An experimental study of boiling liquid expanding vapor explosions (BLEVE) was recently completed at Queen’s University in Canada. The results clearly showed that the severity of the BLEVE was directly related to the energy stored in the vessel, and this energy storage was significantly affected by pressure relief valve (PRV) behavior. During the tests, the PRV operating characteristics were highly variable. Since these valves play a large role in the control of energy accumulation and storage in a pressure vessel, it was decided to study their dynamic behavior in detail and quantify their effect on energy storage. As an initial step, 60 small (1-in. NPT) transport vessel PRVs representing equivalent designs from each of three manufacturers were procured through a third party and tested on an air test bench. These tests were conducted in accordance with the certification procedures specified by various agencies (ASME, UL, CSA, CGA). Four characteristic pressures were measured: simmer (start-to-discharge), pop (full open), reseat, and reseal (bubble-tight reclosure). After initial testing, the valves were stored for various periods of time and retested. This paper details the equipment, procedures, and results of this testing and contains a significant discussion about the expected and observed operation of relief valves. [S0094-9930(00)00702-2]