Conduit developments in hazardous areas

Wherever there is a risk of gas/air or dust/air mixtures or other flammable combinations giving rise to a risk of explosion, the law and specific regulations necessitate the elimination of sources of ignition. Areas must be assessed for the level of risk and equipment used in each area certified by an authorised body as suitable for that area.

There are many types of industry that are affected by this legislation, from offshore oil and gas, to chemical, petrochemical and process industries, building and construction, transportation, marine and defence, food processing and production, water treatment, power generation and many others. Within these areas, there are literally millions of situations where cables that carry power have to be used, and their use must comply with the ATEX directives.

Until now, those specifying cables for such areas had a limited choice and have had to select from the products offered by various cable manufacturers only. The use of a conduit system as an alternative was not an option. Now, however, new product developments from conduit manufacturers have opened the door to a wider choice of solutions. Companies such as Kopex International have developed metallic and nonmetallic conduits that can provide more effective cable management solutions without any compromise in safety or efficiency.

Conduit systems for ATEX applications fall into two categories: metallic and nonmetallic, which are suitable for both indoor and outdoor applications. Liquid-tight metallic conduit is steel cored and has a PVC coating. It is strong and offers a high level of impact resistance, capable of withstanding up to 6 joules, available in different versions that offer varying degrees of oil and chemical resistance, low fire hazard and suitability for use in high temperatures. Nonmetallic systems are now available in new versions and can be supplied with braiding for extra strength, while having the flexibility to be used in intricate applications.

The major advantage of these conduit systems is that they are available in diameters of up to 54 and 63 mm respectively. This allows the conduit to accept multiple cables. The advantages of using conduit instead of individual cores of cables then become apparent in terms of simplicity and reduced costs. The conduit effectively provides multicore protection and, subject to the conduit system selected, offers all the necessary performance characteristics for a given application: EMC shielding with braided conduit, impact/crush resistance, anti-corrosion, high and low temperature operation, oil resistance - indeed anything you would expect from a specialist cable.

Using steel-cored, armoured metallic conduit to protect cables means that standard cables can frequently be used in applications where traditionally more expensive SWA specialist cable would have been specified. One braided conduit can effectively take the place of many expensive braided cables.

An often overlooked cost associated with cables is the cost of glands which need to be specified for each individual cable. Conduit requires only one gland to provide ATEX conformity for several cables. Conduit systems also have great versatility today with fittings available for a wide range of threads including metric, Pg and national pipe thread with threaded adapters to join many different sizes.

The selection of the correct cable management products to ensure compliance with the ATEX Directives for hazardous areas in Zones 1, 2, 21 and 22 classifications is absolutely essential; and there are now no excuses for not specifying cable with the appropriate features and performance. With the advent of new electrical conduit systems, specifiers and contractors are no longer tied to traditional solutions. While cables may be the best solution in some situations, there are now many instances where a conduit system is more appropriate.

*Phil Winship, Technical Manager, Kopex International (distributed in Australia by Adaptaflex).