New explosion-protected trucks from Linde: close to production and meeting the most stringent of safety standards

Linde Material Handling expands its range of explosion-protected trucks for zone 2/22

Proplan Transport- und Lagersysteme GmbH (Proplan), a subsidiary of Linde Material Handling (MH) and a leading manufacturer of explosion-protected industrial trucks, is expanding its range of models for explosion-protection zone 2/22. Newcomers to the range include the Linde T16 EX to T20 EX pallet trucks, which offer load capacities of between 1.6 and 2.0 tonnes, and the Linde V10 EX medium-level order picker, which offers a load capacity of one tonne.

Wherever atmospheres present a risk of explosion, even just briefly, measures must be taken on industrial trucks to prevent instances of ignition caused by hot surfaces, sparks or static electricity. A wide range of directives and regulations form a corresponding legal basis, which manufacturers and operating companies must observe. Among the most notable of these directives are EC machinery directive 94/9/EC for explosive atmospheres (ATEX 95)—which will be replaced by directive 2014/34/EU within the next two years—and the German Ordinance on Industrial Safety and Health (BetrSichV). The latter ordinance breaks down areas at risk of explosion into zones according to the probability of a potentially explosive atmosphere developing.

Zone 0 covers areas where there is a constant risk of explosion from the atmosphere, or where this risk occurs frequently or over long periods. Industrial trucks are not used in these areas. In zones 1 (gases) and 21 (dusts), air only occasionally mixes with flammable gases, vapours and mists or flammable dust present in the air during normal operation. In zones 2 (gases) and 22 (dusts), such mixtures usually do not occur, or only occur for a short period. If a potentially explosive atmosphere develops in the area just once a year, the relevant area must be classed as zone 2/22. Experts also agree that in zone 2/22, a potentially explosive atmosphere of appropriate severity must only occur a small number of times, and for no longer than 30 minutes per operation.

The Linde range of products for explosion-protection zone 2/22 has been expanded. Newcomers to the range include the Linde T16 EX to T20 EX pallet trucks, which offer load capacities of between 1.6 and 2.0 tonnes.

Any equipment that is used in explosion-protection zone 1/21 requires an EC prototype test certificate for safety-related components. These certificates are issued by “appointed bodies”, such as the Physikalisch-Technische Bundesanstalt (PTB — Germany’s national metrology institute), INERIS or the German Technical Inspection Association (TÜV). However, in the case of industrial trucks for explosion-protection zone 2/22, the manufacturer’s quality management system (in line with EN ISO 9001) is sufficient to meet this requirement. To ensure that customers in the chemical, pharmaceutical and food industries can rely on explosion-protected trucks from Linde to the greatest extent possible, the Aschaffenburg-based manufacturer is very strict in enforcing the provisions for zone 2/22. “As a company certified under the terms of EC machinery directive 94/9/EC, Proplan uses the certification for trucks for zone 1/21 as a guide when it comes to trucks for zone 2/22, and independently performs comparable tests on prototypes”, explains Herbert Kunkel, Managing Director of Proplan.

One example of this is the electrical equipment for the “Ex nc” (protection through sealing) and “Ex tc” (protection by enclosure) types of spark protection in gas in the latest range of electric forklift trucks from Linde — the Linde E12 EX to E20 EX. Proplan develops components such as the power modules, display housing, control unit and ignition and starting switch in line with the requirements of DIN standards EN 60079-15 and/or EN 60079-31, and tests these components in collaboration with TÜV Rheinland. To test the equipment, the components are aged in an endurance test performed in a calibrated climatic chamber, and then subjected to both a leak test and an impact test. Only once the component has successfully passed these tests does it receive a certificate of conformity. “Cost-effectiveness must not come at the expense of safety — not under any circumstances”, notes Kunkel, Managing Director of Proplan. “At the same time, we draw on the benefits in terms of cost and quality that come as a result of the Linde series-production process, and work together with the truck developers at Linde MH when developing products, involving them from the outset. By taking this approach, we can ensure our products are both safe and economical.”

In addition to trucks for zone 1/21, which remain safe even in exceptional circumstances, demand has also grown in recent years for trucks for zone 2/22 that are safe in normal operation, according to Kunkel. As such, the truck manufacturer is expanding its range of trucks in this segment. Proplan Managing Director Kunkel continues: “We are adapting to the new and changing requirements posed by our customers. What’s more, we are convinced that, thanks to the high quality and safety standards offered by our trucks for zone 2/22, and the fact that these trucks are close to series production, we will achieve a special position on the market with these products, too.”

The new Linde T16 EX to T20 EX pallet trucks with overall truck certification for zone 2/22 represent a whole range of models that can be used in various areas of the warehouse and production facility. The trucks rival their series-production counterparts in terms of ergonomics, performance and convenience, and are designed to accommodate battery capacities from 150 Ah to 375 Ah. In the EX models, the AC motor, brake, speed sensor and temperature sensor are protected by a housing, and the solenoid valve and control housing are sealed with a casting compound. An appropriate declaration of conformity and/or declaration from the manufacturer serve to prove that these measures have been taken.

The Proplan safety unit (PSU) monitors all electrical functions and ensures that the devices can be used safely in zone 2/22. The features offered by the PSU include a redundant temperature monitoring system, as well as a system for monitoring the temperature sensor for short circuits and cable breaks. Functions to monitor the control voltage and ensure that the main contactors operate correctly are also provided by this unit. Even Zener batteries with a self-resetting fuse for current circuits in line with the “Ex-i” type of spark protection (intrinsic safety) are included in the PSU. As a component that can produce sparks, the lift motor is contained within a pressure-tight housing, as is the case for zone 1/21. What’s more, clamp connections (connector solution) have been completely eliminated. Even the documentation is of the same standard of quality as Linde EX trucks for zone 1/21. All documents are stored centrally at Proplan.

The same safety standards apply for the new Linde V10 EX medium-level order picker for zone 2/22, which boasts a maximum picking height of 6350 mm and features a spring-loaded driver’s platform, an operator console on the load side or mast side, and a lift mast that offers an unrestricted view. “By introducing these new models, we have expanded our range of explosion-protection warehouse and system technology equipment even further”, says Kunkel happily.