Self-ignition of hydrogen releases through electrostatic discharge induced by entrained particulates

The potential for particulates entrained in hydrogen releases to generate electrostatic charge and induce electrostatic discharge ignitions was investigated. A series of tests were performed in which hydrogen was released through a 3.175-mm diameter orifice from an initial pressure of 140 bar. Electrostatic field sensors were used to characterize the electrification of known quantities of iron oxide particulates deliberately entrained in the release. The ignition experiments focused on using charged particulates to induce spark discharges from isolated conductors and corona discharges. A total of 12 ignition events were observed. The results show that electrification of entrained particulates is a viable self-ignition mechanism of hydrogen releases.

► Measured accumulation of charge on iron oxide particulates entrained in hydrogen jets.
► Investigated particulate induced spark discharge ignition.
► Investigated particulate induced corona discharge ignition.
► Results showed that entrained particulates can be a source of spontaneous ignition.
► All ignition events observed occurred in close proximity to ungrounded metal.