Explosion Protection Page

Explosion Protection
“An atmosphere is liable to explode if the air mixes with a flammable substance (gas, dust or flyings) in a manner that a spark or the surface temperature of a piece of equipment can cause it to ignite.”
“Ex” or Explosion Protection attempts to cover all aspects which will prevent such an occurrence. Ex is an acronym for Explosion Protected. The designators, such as EEx and AEx, do no more than define the area in which the Ex is used.

The AEx symbol is used in the US for the Zone system only. The EEx is used in most European countries and the Ex is used in Canada. It may be noted that, in Canada, as in the US, all Ex equipment will require approval by independent testing laboratories.

Selecting Electrical Apparatus
Criteria to apply when selecting Ex electrical apparatus:

• The type of protection concept of the apparatus in relation to the location classification;
• The temperature classification of the apparatus in relation to the ignition temperature of the gases and vapors involved;
• The apparatus gas group (where applicable) in relation to the relevant properties of the gases and vapors present;
• The apparatus construction in relation to the environmental conditions.

Explosion Protection
Zone 0–Locations where a dangerous atmosphere, at risk of explosion, is always present or is present for long periods of time.

Zone 1–A location in which an explosive gas-air mixture is likely to occur in normal operation.

Zone 2–A location in which a gas-air mixture is not likely to occur and if it does occur it will be for a short period of time.

EXAMPLE OF ZONES ON A LIQUID CONTAINER

An atmosphere is likely to explode if a hazardous gas mixes with air in the proper proportions, and contacts an arc, spark or the overheated surface of electrical equipment. Explosion Protection, or Ex, with Increased Safety (Ex “e”) and Intrinsically Safe (Ex “i”) design attempts to cover all aspects of electrical equipment so as not to allow the contact of hazardous gas and an ignition source. Sparks and hot spots may be created by terminals that can work loose. Static discharge can also create an ignition point.
The requirements that lead to Ex designs are varied with respect to the codes which govern the site in which Ex work is being accomplished.

The definitions of Zones differ from one code to another, but all the codes have been written to mean basically the same–Explosion Protection. It is to this end that Rose+Bopla has designed and supplied the enclosures that have been utilized in Europe for many years.
The standard Division classification system in the US and Canada is giving way to the Zone system. With this system there comes a cost savings of up to 90%, just in the cost of enclosures; less the cost of installation, due to smaller and much lighter enclosures; as well as lower maintenance costs; all resulting in lower extended costs.

Continued

We have attempted to present the information about our enclosures on this website in a straight-forward manner. We offer this information as accurate at the time of publication. Specifications are subject to change without notice. Rose+Bopla Enclosures is not responsible for inadvertent errors.


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Ex EXPLOSION PROTECTION