The Effect of Grease Contaminants on Cryogenic Pressure Relief Device Performance

Pressure Relief Devices (PRDs) are essential for maintaining the design pressure of cryogenic hydrogen systems. However, degradation and contamination of PRDs through routine testing and operation can adversely affect performance. In 2016 the Hydrogen Properties for Energy Research (HYPER) laboratory experienced a near-miss safety event after a PRD failed to open at a design pressure. A likely cause of the failure was attributed to the presence of vacuum pump oil deposited near the PRD valve seat that froze during the event. To investigate this risk, an experiment was designed to test the variability of common PRD relief pressures at room temperature and at 77 K after exposure to small amounts of vacuum grease and vacuum pump oil. Results are presented along with recommendations for testing and maintenance of PRDs operating in cryogenic systems.