In areas with flammable gases, vapours or dust, a spark or a hot surface can ignite the atmosphere. An explosion-proof (ex-proof) crane or hoist is designed so that it does not become the source of ignition.
This guide explains how hazardous areas are classified, what protection a crane needs, and what to tell your supplier.
Where explosion-proof cranes and hoists are used
- Gases, mist and vapours: chemical industry, refineries, gas supply, pharmaceutical industry, wastewater treatment, distilleries and mining.
- Dust: silos and mills, wood processing, paint shops, grinding shops, feed production, bulk material handling and synthetic fibre production.
Why an explosion happens
An explosion needs three things at once: a flammable substance (gas, vapour or dust) within certain concentration limits, air with a minimum of oxygen, and an ignition source of enough energy or temperature. Flammable gases need very little energy, such as a spark or a hot surface, so the surface temperature of mechanical and electrical equipment matters as much as sparks. Dust behaves differently as a layer, which can smoulder on a hot surface, and as a cloud, which can explode on contact with a hot surface.
How a hazardous area is classified
Hazardous areas are divided into zones by how likely and how long an explosive atmosphere is present. Zones 1 and 2 apply to gases and vapours, and zones 21 and 22 apply to dust. The classification is the responsibility of the plant operator, together with experts in the subject.
- Explosion group: for gases, group IIA (for example propane), IIB (ethylene) and IIC (acetylene, hydrogen); for dust, fibres and flyings such as wood, paper and cotton, grain dust, and metal or coal dust.
- Temperature class: the highest surface temperature the equipment may reach. For dust it is stated as the temperature itself, for example T120 °C.
- Type of protection: how the equipment is made safe, for example flameproof enclosure (d), increased safety (e) or protection by housing (tD).
- Enclosure rating (IP): protection against dust and water, independent of explosion protection.
Standards
CESAN explosion-proof hoists and crane components comply with the European ATEX rules, the FEM regulations, IEC 60079-14 and the European safety standards (EN). Equipment first put into operation after 20 April 2016 needs an EU Declaration of Conformity under Directive 2014/34/EU, which replaced Directive 94/9/EC.
The CESAN explosion-proof range
- CCex electric wire rope hoists for loads up to 80 t, as a single hoist or as part of a CraneKit, on a single or double girder trolley or foot-mounted.
- SKex electric chain hoists, with options such as IP66, stainless steel chain, hook and hook block, and a bronze-coated hook.
- CRAFTsterEX hand chain blocks for loads up to 20 t, needing no power connection. They are marked for gas Ex II 2G c IIC T4 and dust Ex II 2D c T120 °C.
- CraneKitEX crane component packages for loads up to 80 t. They contain everything needed to build an Ex crane except the crane bridge, with one EC Declaration of Conformity for the hoist, power supply, end carriages, travelling machinery, cables, terminal boxes and bridge panels.
The range covers zones 1 and 2 for gas and zones 21 and 22 for dust.
What the protection looks like in practice
- Motors: for zones 1 and 21, a combination of flameproof enclosure (d), increased safety (e) and protection by housing (tD). For zone 2, non-sparking equipment. For zone 22, IP66 with protection by housing (tD).
- Control panels: flameproof (d), increased safety (e) or protection by housing (tD), with large covers for easy installation and maintenance.
- Cable entries: indirect cable entries for the flameproof and increased safety types of protection.
- Control pendants: robust switches with a standard EMERGENCY STOP button.
- Spark protection: hooks can be bronze-coated; running wheels can be made of brass from 1 m/s travel speed, which adds some maintenance.
- Ambient temperature: for example -10 °C to +40 °C for CCex wire rope hoists; SKex chain hoists are rated -20 °C to +40 °C, with an option up to +50 °C.
What to tell your supplier
- The zone, the gas or dust group and the temperature class.
- The certification or standard your site requires.
- Capacity, span, lifting height and duty class.
- Ambient temperature, humidity and corrosive conditions.
- Control method: pendant or radio remote.
Installation and maintenance
Using explosion-protected equipment is not enough on its own. Design, installation, testing and maintenance of all electrical and mechanical systems must follow the standards and regulations in force. Use only approved spare parts, keep enclosures sealed and follow the manufacturer’s inspection plan.
Why choose CESAN
- Turkish manufacturer since 1976. CESAN designs and builds overhead, gantry and jib cranes and hoists in its own factory in Turkey, with engineering, sales and after-sales in one country.
- Projects in more than 52 countries. Experience with different standards, climates and site conditions.
- A full range. Single girder cranes up to 32 t, double girder cranes up to 250 t and gantry cranes up to 500 t, plus jib cranes, hoists, transfer carts and attachments.
- Recognized standards. Design to FEM 1.001, EN 13001 and ISO 4301, CE marking, and ISO 9001 and TSE certificates for the company.
- Installation and commissioning on site. CESAN handles installation, commissioning and the load test in any country.
- Factory acceptance test (FAT). The complete crane system is tested before delivery, and customers or third parties can witness the tests.
- 24-month warranty, with the terms stated in each quotation.
- An office in Dubai for Gulf customers.
Send us your requirements
To prepare an accurate offer we need the zone, gas or dust group, temperature class, capacity, span, lifting height and duty class. Send them through the enquiry form and our engineers will reply with a technical and budgetary assessment.
See our overhead cranes and the guide to CE, FEM and DIN.