Plastics casings for the type of protection `flameproof enclosure d´

In explosive atmospheres, electrical components which, during operation, constitute potential ignition sources (due for example to their high surface temperature or a spark at break) must be installed in a casing of the type of protection `flameproof enclosure d´. This casing must both withstand and explosion on the inside and be flameproof. For many years, the manufacturers of electrical equipment have used plastics for flameproof casings of small volume. Due the the specific stressing of the material at higher volumes, however, the standard characteristics available for the design are not sufficient. The authors therefore develop a specific test method which allows the influence of the main risks on strength and fracture behaviour of different types of plastics to be determined. The results of the test are intended to be a help in selecting the material and the wall thickness of the casing