Dilution in pressurized enclosures – critical points

Abstract

The risk of explosion can occur in all activities involving flammable substances which, when mixed with air, can form an explosive atmosphere. Explosion protection is intended to prevent the ignition of explosive atmospheres. Pressurization, as a type of protection, 'p' is based on the introduction of a protective gas (air or inert gas) in an enclosure to prevent the formation of an explosive atmosphere within the enclosure by maintaining an overpressure relative to the surrounding atmosphere and, where necessary, by the use of dilution. The important tests for explosion protection by pressurization type of protection are based on the filling and purging test. Each of these involves monitoring certain points within the pressurized enclosure to confirm that concentrations are within acceptable limits. The location of these monitoring points can be identified by using computer simulations. This results, in so-called critical points, where the concentration lastly reaches the pre-set values. These critical points bring the advantage of the need to monitor concentrations at a much smaller number of points and thus it is increasing the accuracy of the tests. Following the approach of the work and the experiments carried out, it was found that computer simulation is effective for establishing critical points.