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What Is an Explosion?

Ex|plo|si|on; -s <lat.> (explosio) means "escaping under pressure." What happens during an explosion, which factors are important and what protective measures are available? You will learn everything you need to know about explosion protection right here.

ISO 8421-1, EN 1127-1 defines an explosion as “a sudden oxidation or decomposition reaction with increase of temperature, pressure or both at the same time.” This refers to a chemical reaction that with a simultaneous convergence of oxygen (air), a flammable material and a source of ignition in a particular ratio, causes temperature and pressure to increase abruptly. If the heat that arises cannot be discharged quickly enough, there is a sudden volume expansion of the concurrent gases and a release of great heat energy accompanied by a pressure wave: the explosion.

WAGO in Explosion Protection

Principles of Explosion Protection

Everything worth knowing about Ex protection at a single glance.

Severity of the Explosion

The severity of an explosion depends on the properties of the flammable materials and the mixture of these materials with oxygen: the oxygen present in the air burns only with a particular quantity of the flammable material (oxidation). Depending on the severity of an explosion and the associated spread speed of the pressure wave, a distinction is made between low-speed detonation (cm/s), deflagration (m/s) and the strongest type of explosion, the detonation (km/s). The most severe of the explosions spreads at a rate faster than the speed of sound, thus developing immense destructive power.

Prerequisites for an Explosive Atmosphere

The following factors must be present simultaneously for an explosion to occur:

  • A flammable material in the production process or surroundings
  • Oxygen (air)
  • Ignition source
  • A particular ratio between oxygen and flammable material

The knowledge that an explosion only arises as soon as an atmosphere subject to explosion and a source of ignition are available simultaneously is relevant for explosion protection.