Propagation and suppression of gas and dust explosions.

Explosion suppression system design has relied historically on the validity of Hartmann apparatus explosibility test data, and on interpolation from available suppression system test data. This research has identified improved methods of explosion hazard assessment and suppression system efficacy assessment, from a study of explosion propagation, suppressant action, and discharge of suppressors. The controversy over the validity of Hartmann dust explosibility data was resolved. It was found that the ignition methodology was responsible for the uncertainly of Hartmann data. A 43dm[3] spherical explosion test apparatus was developed which provided more useful explosibility data. The influence of turbulence on explosion hazards was recognised and an empirical measure of turbulence level was defined. Systematic trials with suppressed and unsuppressed explosions were undertaken in a 1m[3] apparatus. The results of these trials provided the foundation for the development of a mathematical model of explosion suppression. A 6.2m[3] explosion test facility was set up in alignment with the requirements of a proposed International Standard. Explosion and explosion suppression trials in this apparatus substantiated the model. Certain artefacts were identified in 6.2m[3] quiescent gas explosions. An interactive computer program based on the model for explosion suppression was tested and proved. The work has culminated in the establishment of a large scale explosion test facility in the UK. The effectiveness of three suppressants, Halon 1011, water, and mono-ammonium phosphate powder, against both gas and dust explosions was established experimentally . The influence of suppression system detection pressure and explosion suppressor discharge characteristics on the resultant suppression system effectiveness was determined experimentally. A computer model of explosion suppression has emerged which provides an improved level of confidence in adjudging the performance of explosion suppression measures. Areas for further work include larger scale explosion and explosion suppression trials and a study of artefacts identified with large volume quiescent gas explosions