ATEX Hazardous Area Control Stations Zone 22 – Craig & Derricott
Combustible and potentially explosive atmospheres include gases, mists, vapours and dusts – an explosive atmosphere can be created by the presence of non-conductive dust mixed with air, this is designated as a Zone 22 hazardous area.
ATEX category 3D non-conductive dust
Zone 22 Control Stations
Craig & Derricott hazardous area control stations are ATEX certified (Group II) for safe use in Zone 22 potentially explosive atmospheres. Control stations can incorporate single or double push buttons, emergency push button and emergency stop start options – hazardous area “stop starts” are manufactured from die-cast aluminium with emergency stop and start contacts configured to client specification.
Zone 22 Hazardous area
Explosive dust atmosphere not likely to occur in normal operation but may be present for short periods
Bespoke Control Stations For Hazardous Areas
T&D’s in-house CAD drawing facilities produce hazardous area certified control stations for international oil, gas and petrochemical projects – ATEX certified for Zone 1, 2, 21 & 22 gas and dust atmospheres.
T&D assemble a wide range of “stop start” control station with multiple combinations and functions, this includes Zone 22 control stations – we also stock hazardous area enclosures for LV-HV power, control and instrumentation applications.
ATEX hazardous area zones for dusts
Potentially explosive dust atmospheres are categorised into 3 hazardous area zones, based upon the grade of explosion risk according to EN60079-10-2:2009.
Zone 20 Hazardous area
Continuous release inside a dust containment enclosure is classified as a Zone 20 hazardous area – a place in which an potentially explosive atmosphere, in the form of a cloud of combustible dust in air, is present continuously, or for long periods or frequently for short periods. For example, a mill or pneumatic conveying system.
Zone 21 HAZARDOUS AREA
Primary grade of release is classified as a Zone 21 hazardous area – a place in which a potentially explosive atmosphere, in the form of a cloud of combustible dust in air, is likely to occur occasionally in normal operation. For example, bagging points and inspection ports that are frequently opened.
Zone 22 HAZARDOUS AREA
Secondary grade of release is classified as a Zone 22 hazardous area – a place in which a potentially explosive atmosphere, in the form of a cloud of combustible dust in air, is not likely to occur in normal operation but, if it does occur, will persist for a short period only. For example, leaks from incorrectly fitted lids or spillages.
This could also include hazardous areas in the vicinity of devices containing dust, protection systems or components from which dust leaks and forms deposits (e.g. milling / grinding facilities, from which dust leaks and forms layers).
Dust Ignition protection ‘td’
In Europe, ATEX is accepted to be the most important explosion protection concept for dust atmospheres.
EN 50281-1-1 stipulates the ignition protection type for the constructive explosion protection of electrical equipment: “Protection by Enclosure.”
2 dust protection degrees are defined for dust explosion protection:
1. Dustproof – for the use of devices in hazardous area Zone 20, Zone 21 and even in Zone 22 (in the presence of conductive dust)
2. Dust-protected – for use in hazardous area Zone 22a (where non-conductive dust is present)
Contact T&D for competitive prices and delivery for Zone 22 control stations.
Craig & Derricott hazardous area isolators provide safe low voltage electrical isolation for Zone 1 and Zone 2 with Ex d (flameproof) and Ex e (increased safety) protection options.
➡ For complete technical information, hazardous area certification and product specifications about Zone 22 Isolators please see the product sections below.
Visit Zone 1 & Zone 2 Hazardous Area Isolators for further information about “stop start” and emergency control stations for potentially explosive gas and vapour atmospheres.