Fire Rated Shutter installers Westwood Security have announced the addition of a range of Atex approved three phase motors which can now be installed in our range of fire shutters.
When fitting a fire shutter under conditions were a possibility of an explosion is present, Westwood Security now supply ATEX asynchronous type motors in any fire rated shutters installed. These motors are a sealed unit whch is beneficial in the aforementioned conditions – defined as an “explosive atmosphere”. This type of atmosphere features a mixture of air, with flammable substances in the form of gas, steam, mists or dusts in which, after the prime, the combustion propagates together with the mixture not burned.
Dangers emanating from static electricity and from electrical sparking from an unprotected motor are recognised under both UK Health and Safety legislation and also by the European Union. The latter has recently thrown its weight behind an initiative to deliver higher levels of safety in plants where explosions during manufacture or storage are a threat. Since summer 2011 ATEX certification has been mandatory for processing plants.
The key element of ATEX certification is a risk assessment and factories now require an Explosion Protection Document, which can be requested by Health and Safety Executive inspectors.
The Directive gives indications on the Division of the areas in which potentially explosive atmosphere can develop.
The areas at risk of explosion are divided into zones depending on the frequency and the duration of the presence of explosive atmosphere and to the type of dangerous substance, more precisely:
Zone 0: area in which the presence of an explosive atmosphere, made of a mixture of air and flammable substances as gas, steam, mists, is permanent, or it lasts for a long period or it happen frequently.
Zone 1: area in which, during regular activities, is probable the development of an explosive atmosphere made of a mixture of air and flammable substances as gas, steam and mists.
Zone 2: area in which during regular activities, it is not probable the development of an explosive atmosphere made of a mixture of air and flammable substances as gas, steam or mists, and when, even if that happen, is just for a short term.
Zone 20: area in which the presence of an explosive atmosphere, in the form of a cloud of combustible dust in the air, is permanent, or it lasts for a long period or it happen frequently.
Zone 21: area in which occasionally, during regular activities it is probable the development of an explosive atmosphere in the form of a cloud of combustible dust in the air.
Zone 22: area in which during regular activities it is not probable the development of an explosive atmosphere in the form of a cloud of combustible dust and, even if that happen, it is for a short term.
Besides the classification of the work-area it must be defined other two basic parameters to execute an ATEX
analysis, i.e. the group membership of the equipments that is divided in:
Group I: it includes the systems that will be use in the underground caves and in their installation on the surface,
exposed at the risk of firedamp and combustibles dusts release.
Group II: it includes the systems that will be use in environment where explosive atmospheres are probable.
The Classification data’s of the areas at risk of explosion allow classifying the systems in the following categories:
Category 1: it includes the products designed to work and to guarantee the level of protection requested even in case of exceptional failure of the device. In case of failure of one of the protection devices, at least one independent device assures the level of protection requested. In case of two different failures, one independent from the other, the level of protection requested is guaranteed.
Category 2: includes products designed to function and guarantee a high level of protection to work in environment where there is the probability that explosive atmosphere can develop. That can happen for the presence of gas, steam, mists or air and dust explosive mixture.
Category 3: includes products designed to work and guarantee a regular protection level to work in environment where there are scarce probability that explosive atmospheres due to the presence of gas, steam, mists or air and dust mixtures, can appear, and even if that occur, it is for a short term.
Another basic data is the maximum surface temperature allowed.
Motors for zone 21 and 22
In case of use in areas with dangerous potentially explosive atmosphere it must be verified the suitability of the motor in the classification of the zone and to the flammable substances that are in the system. The essentials safety requirements against the risk of explosion in the classified areas are fixed by the European Directives: