Sealing cable ducts in hazardous areas according to the ATEX directive
23 November 2017
The following short update is written to provide clarification on the requirement to seal cable ducts in hazardous area locations according to the ATEX Directive – ATEX is a EU applicable directive to protect and ensure worker and workplace safety for equipment to be installed in potentially explosive atmospheres.
ATEX Directive relates to equipment which is used in hazardous areas i.e. locations with concentrations of flammable gases and vapours creating a potentially explosive atmosphere.
Specifically ATEX relates to equipment with moving parts posing a potential source of ignition (such as fuel dispensing equipment, gears, motors, pumps, mining equipment, lighting, alarms, plugs, switches, sensors etc).
The comments and conclusions below apply to sealing all types of electrical cables both onshore and offshore – including control, instrumentation and power supplying medium and high voltage electricity, typically entering substations at 11kV-33kV.
Equipment is only considered to be within the scope of the ATEX Directive if it is intended (either in whole or in part) to be used in a potentially explosive atmosphere. If a product containing an intended potentially explosive atmosphere, for example a vessel, itself contains equipment as defined in the Directive, then the latter equipment is in effect in a potentially explosive atmosphere, albeit one which is contained by the vessel, and is therefore subject to the ATEX Directive.
Potential sources of ignition: electric sparks, arcs and flashes, electrostatic discharges, waves, ionising radiation, hot surfaces, flames and hot gases, mechanically generated sparks, chemical flame initiation and compression.
If equipment containing a potentially explosive atmosphere can, due to its construction, operation etc. create a potentially explosive atmosphere itself, which wholly or partially surrounds it, then such equipment is in effect in a potentially explosive atmosphere, and is therefore subject to the Directive.
A third scenario is that there may not only be a surrounding potentially explosive atmosphere but also a process that requires such a mixture to enter and/or be released from the product. The interface between the equipment and the process input/ output will also require consideration. This may, in some cases, lead to equipment having more than one Category, one (or more) for the external atmosphere and another for the process atmosphere.
According to the ATEX Directive download opposite Section 2 and 3.7 covers the type of equipment that the hazardous area certification covers – the document does not reference products excluded from the Directive.
Duct sealing systems are not covered or categorised according to ATEX – they are effectively “non-sparking” and when installed in accordance with the manufacturers installation instructions do not pose a potential explosion risk. In this instance, a “Statement of Exclusion” applies to cable sealing.
Duct seals are available to prevent water ingress and gas migration into electrical substations, infrastructure and buildings – fire resistant cable seals are available for fire-rated applications. Sealing solutions are available to suit all duct diameters and cable voltages in single, multiple or trefoil cable arrangement.
This information has been provided by SIRA, the leading hazardous area certification body.
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