In many industries dealing with flammable, combustible and explosive materials such as petroleum, petroleum products, chemistry, LPG, natural gas, coal mines, grain silos, sugar factories, timber and furniture factories, bread ovens and factories, such as normal operation or breakdown and maintenance. In such cases (for reasons such as gas, dust, or flammable substance vapor), an explosive atmosphere occurs. Sparks and arcs from electrical appliances endanger these environments and cause explosions. For these reasons, the electrical appliances used in the explosive environments of such workplaces must be different. This event is called ex-proof and the electrical appliances used are called ex-proof electrical products. In short, they are known by these names in the commercial market. In fact, the term EX-PROOF was taken from the American practice and should be in Turkish as "EXPLOSIVE ENVIRONMENTS and ELECTRIC TOOLS USED IN EXPLOSIVE ENVIRONMENTS".
The term "EXPLOSION PROTECTED" can also be used instead of EXPROOF.
What is an Explosive Environment?
Places where explosive, flammable and combustible gases, dust or vapors mix with air and become explosive atmospheres are called explosive atmospheres. This is the short description of explosive atmosphere. Three elements must come together in order to create an explosive atmosphere and create a hazard.
A. Explosive substance; Explosive, flammable and combustible gas, vapor or dust
B: Air (Oxygen) A: Energy, a spark or power source that will ignite the explosion. If one of these three elements can be disabled, there is no danger of explosion.
Commonly known explosive gases are natural gas, bottled gas (LPG) used in homes, and hydrogen and acetylene gases used in welding works. These gases become explosive when mixed with air and can explode with any trigger (spark). The explosion depends on the mixing ratio with air. The mixture has a lower and an upper explosion limit. Those interested in gases refer to the measurement of LEL, which is the English abbreviation of the lower explosive limit (LEL= lower explosive limit). Since the term LEL is used all over the world, the same symbol is used in our article. The LEL value is a very important data for the measures to be taken and determines the degree of danger (explosiveness) of the gases. Likewise, the upper explosion limit of gases is called the UEL. (UEL= upper explosive limit)
Petroleum products (such as gasoline, benzol, diesel oil, thinner) are the leading known "flammable, flammable and explosive" liquids. Flammable liquids evaporate and mix with the air, creating an explosive atmosphere. The evaporation of liquids depends on the ambient temperature. The lowest temperature that creates liquid vapor in explosive consistency (at a rate) is called FLASH POINT. This value, like the LEL in gases, is an important data for the measures to be taken and determines the degree of danger of liquids. Liquids are divided into hazard classes according to their explosion points. These classifications are made according to the American NFPA 30 standard and the American practice dominates the world.
SOLID MATERIALS, POWDERS
Mixing of dusts with the oxygen of the air is possible either in the form of a “dust cloud” or in the form of a thin layer. Dusts are usually adhered to the plant in the form of a thin film. A very small part of the combustible dust may become incandescent with any heat source coming from the heating of the facility or from the outside, causing an explosion. This very small portion that explodes blows other dust into the air, creating an "explosive dust cloud". This cloud explodes even more violently, and the dust explosion can turn into a chain reaction, in other words, a "walking explosion" disaster, as the exploding cloud will help create new dust clouds. Dust explosions are much more dangerous and destructive than gas explosions.