Summary of experiment series E4.3 (Electrostatic Ignition) results

This effect could be larger with different initial conditions either at the nozzle or in the tanker. The wall current measurements were more consistent, as the ability for LH 2 to induce a current on a section of electrically insulated pipework was clearly demonstrated. This charge is a complicated function of the phase of LH 2 in the pipework, the turbulence of the flow, and the resistance to ground of the section of the pipework.

Frost formation on the outside of the pipework dynamically changed the resistance to ground throughout each trial, making interrogation of the results difficult. The experiments show that electrostatic charges do pose a credible hazard when considering LH 2 facilities. The charging, however, does not form inside the hydrogen, but on the substances or objects that the hydrogen interacts with.

For a fixed facility, maintaining continuity to earth, paying attention to objects in the potential path of a release, would limit the likelihood of electrostatic charging and therefore limit the hazard.