Flameproof barrier gland is ATEX-compliant

An ATEX-compliant, flameproof barrier gland from Kopex uses a rubber pot in place of a conventional metal sleeve surrounding putty, in electrical conduit and fittings.

The influence of the ATEX Directive is spread far and wide, covering industries and applications as diverse as oil and gas exploration, food processing, brewing, pharmaceutical production, paint spraying, flour milling and the storage of grain in silos - indeed, anywhere that a potentially explosive combination of a fuel, oxygen and ignition source are all present.

Of course, the conditions also have to be right for an explosion to occur, which means that factors such as the temperature and the ratio of fuel to oxygen also have an influence.

Nonetheless, ATEX compliance is only, strictly, required for equipment placed on the market within the European Union.

Elsewhere, national standards must be applied (such as in the USA), or countries can adopt other national or international standards.

For example, in the Middle East oil industry there are some regions where USA standards dominate and others where alternative standards are commonly encountered.

So, from this it can be inferred that ATEX is bound to have an influence far beyond the EU.

While there has been a great deal of attention paid to primary equipment destined for use in hazardous areas, some types of component have occasionally been neglected.

In a few cases this has been through ignorance, but more often it has been due to a lack of suitable products.

Electrical conduit and fittings, for example, are commonly used within hazardous areas and, although flameproof barrier glands have been available for many years, the ATEX Directive imposed additional requirements that mean many of the tried-and-tested barrier glands still do not match the ATEX requirements.

One of the demands made by the new Directive is that it should be possible to dismantle glands sealed with two-part epoxy putty in order to inspect the putty for complete filling of the void and, therefore, visually confirm the integrity of the flamepaths.

Traditional designs of barrier gland have invariably been constructed from brass or stainless steel.

Unfortunately, the putty is specifically formulated to adhere to metals and cable insulation, meaning that the joint cannot be disassembled for inspection.

However, a new design of ATEX-compliant flameproof barrier gland, from Kopex, uses a rubber pot to take the place of the conventional metal sleeve surrounding the putty.

It is moulded from a special low-friction grade of elastomeric material, which allows the rubber pot to be eased off the cured putty for inspection.

Moreover, if voids are present, additional putty can be inserted and the joint remade and re-inspected.

To maintain earthing continuity, despite the use of the rubber pot, the Kopex fitting incorporates an earthing spring.

Users of conduit who now find that they have to install ATEX-compliant fittings may wonder how they can tell an ATEX-compliant fitting from a non-compliant fitting.

In fact, this is easy because the ATEX Directive lays down exactly what information must be marked onto components.

Essentially this information relates to the manufacturer (name and postcode) and the certification (name of Notified Body - typically Baseefa (2001) for UK manufactured products - along with the CE and hexagonal Ex logos, the Ex, IP and temperature ratings, and the certificate number).

Something that is not clear from the extensive markings is that fittings and conduit are approved as a complete system, so it is essential that the correct grade of conduit is used.

So, for example, the Kopex ATEX flameproof gland is approved when used with the company's Liquid Tight range of flexible metallic conduit and no other.

Provided that complementary fittings and conduit are used, the requirements of the ATEX Directive will be met and the resultant connection - typically between a motor and control panel - will give long, trouble-free service.

If, on the other hand, visually similar, but incompatible conduit and fittings are used, the ATEX requirements will not be met, the gland will not provide the vital flameproof protection, or premature failure could occur.

Similarly, packing putty into a standard gland in an attempt to make it flameproof is a recipe for disaster.

Users should always ensure that fittings used in hazardous areas are clearly marked with the appropriate ratings and approvals, that the correct type of conduit is being used, and that the assembly instructions are followed precisely.

Flexible metallic conduit provides an excellent means of connecting fixed equipment (such as control panels) to equipment that is subject to small movements due to vibrations or structural deflections and generally for all shorter runs where protected cables are required.

For longer runs then it is usual for armoured cable and certified glands to be used.

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