Vehicles for hazardous areas
14 December 2016
With the proliferation of electric vehicles, one area that is seeing particular expansion is that of explosion-proof vehicles are aimed at market segments dealing with potentially hazardous environments such as the chemical and petrochemical industries, oil and gas production sites. In this article, Lamberto Salvan of Italian transport specialist Alkè Electric Vehicles gives an overview of this crucial area.
Electric vehicles used in these areas are designed to avoid any ignition risk in the surrounding atmosphere during their normal use and are built using special, certified components.
These explosion-proof vehicles can work in risky areas with a potentially explosive atmosphere - gases or flammable vapours (zones 1 and 2) or flammable powders (zones 21 and 22) - and can be certified in accordance with European ATEX and North American NFPA/NEC standards, or with reference to other important international standards such as IECEx, CNEx, etc.
Compact vehicles are available with a loading capacity up to 1,500 kg and towing capacity up to 4,500 kg, with a maximum range of 100 km on a single charge. They can accommodate from 2 to 6 people, and some types can carry people, goods and materials.
These vehicles can be used for logistics, maintenance, first aid, fire-fighting, surveillance, and some can have cranes and other equipment incorporated.
These electric vehicles use mainly AC motors with high torque and gradual power distribution, preventing the risk of sliding or poor grip even on terrain that is traditionally considered to be high-risk (sand, snow or ice). In addition, they guarantee immediate uphill standing starts. Furthermore they have an energy recovery motor braking system (regeneration) which avoids power wastage and brake wear when stopping, and simultaneously recharges the vehicle battery.
These explosion-proof electric vehicles have specific design and safety features covering the electrical system (batteries, connectors, sensors, control unit, etc.) and all those non-electric parts that could generate high temperatures or sparks (mechanical parts, brakes, plastic elements, etc.).
The surface temperature is checked by specific temperature sensors, according to the temperature class and the temperature limit requested, to avoid the risk of overheating. If this occurs, the vehicle will automatically shut down.
An earth leakage check system automatically shuts the vehicle down in case the max value should be exceeded, lighting the indicator on the dashboard panel. An appropriate “Reset” pushbutton allows these vehicles to be moved out of the dangerous area in case of temperature and earth sensor alarm activation.
The electric wiring system has armoured cables for ducts subject to movement or without any mechanical protection. The disk or drum brakes are equipped with wear and temperature sensors to avoid sparks caused by friction between metal, and to prevent friction which might exceed the value of the required temperature class and limit.
The seats are for most versions covered with an antistatic material and, where necessary, the external plastic surfaces are treated with electro-conductive paint. All tyres are electro-conductive.
Accessories, such as flashing beacon, reversing beeper, headlights, etc. are obviously explosion-proof when installed.
Benefits of these explosion-proof vehicles include:
• Minimising time taken for transportation of equipment and employees
• Bringing more efficiency to surveillance/monitoring activities
• Providing rescue units and compact firefighting units with the ability to enter hazardous areas to support injured people in case of accidents
• Minimising time taken for cleaning and waste collection activities
• Bringing more efficiency to maintenance operations
• Improving the general efficiency of the plant
• Providing a healthy and safe work environment
• Minimising shut-down times
• Not requiring inspection before entering the plant
• Eliminating risk of explosion in case of human or inspection equipment errors
Over the last five years we have seen the introduction of some very innovative explosion-proof electric vehicles designed for use in the hardest, most demanding conditions, such as the frozen wastelands of Siberia and northern Europe or in the extreme temperatures of the Sahara desert and other remote locations in the Middle East and Africa.
For these models comfort in the cab is state-of-the-art, with air-conditioning systems designed to work in extremely hot environments with temperatures of up to 55°C, and with electric heating systems for use in the cold – both, of course, with anti-explosion certification.
Such has been the expansion of the offer in recent years that explosion-proof vehicles are now available to work in most situations where there are explosion risks around the world.
Contact Details and Archive...