Merck is a leading science and technology company in the fields of healthcare, life science and performance materials with around 50,000 employees. In 2016, Merck generated sales of € 15 billion in 66 countries.

Special solutions for sensitive work areas
At the end of 2015, Stöcklin had already expanded the Merck forklift fleet at the headquarters in Darmstadt with a series of modern electric pedestrian stackers. These vehicles comply with the ATEX Directive 2014/34/EU (ATEX = Atmosphères Explosibles) in analogy to the European Directive 94/9/EC for the placing on the market of explosion-proof electrical and mechanical machines and components. They are suitable for use in Zone 1, where an explosive gas atmosphere may occasionally be present, as well as in Zone 21 for explosive dust atmospheres.

As a specialist for customer-specific solutions, the Swiss OEM manufacturer adapted the electronically driven Ex devices according to further specifications from Merck. For example, there was a request for a modified foot protection strip, stainless steel welding on the wheel arms to reduce sparking and a special circuit for brake override so that the vehicle can be recovered from a hazardous area such as an Ex zone in the event of repairs. Other requirements included an increase in the load capacity from 1,600 to 1,800 kilograms, a load protection grid and the relocation of the key switch and warning light to the chassis.

Weighing up opportunities and risks
In view of the range of products on offer, the logistics processes at Merck are characterized by the highest level of safety awareness. Risks arise, for example, when handling flammable gases, vapors and dusts. For the industrial trucks in use, this means that internationally valid certificates and type examination certificates must be submitted in advance to prove that safe operation is also possible in potentially explosive environments without further modifications.

The application of lithium-ion batteries for standard appliances had to be examined in the same way. Characteristic features of this alternative to conventional lead-acid batteries include a higher energy density and longer service life, which increase the availability of vehicles. Nevertheless, there is still skepticism, which is fueled by reports of batteries catching fire, for example in smartphones. "Lithium-ion batteries are still the subject of controversy. Nevertheless, we have decided to use this technology in a Stöcklin forklift truck, initially on a trial basis. The advantage of lithium-ion batteries in our application is the elimination of central charging stations with extraction and monitoring of vapors. The devices can be charged directly in production areas (with sufficient safety distance). This has particular advantages for new buildings and in the GMP area," says Bernd Hoerr (Vehicle Management Merck).

At the same time, specific safety aspects defined by Merck had to be taken into account: "The design, the control system and the composition of the battery were important to us here. We were particularly pleased with how Stöcklin implemented the design and control system. Because many points were taken into account in advance, the device could be put into operation at short notice after a risk assessment with the specialist department, operator, occupational safety and fire department," Hoerr continues.

Tested and documented safety
A delegation of representatives from the company fire department, operational safety, battery management, purchasing management and project management initially examined the use of lithium-ion batteries in external practical applications. On site, it became clear that this technology is already widely used and that there are no significant problems when handling the battery. "After further discussions and a risk analysis by those responsible at Merck, which was actively supported by the provision of all important data by Stöcklin, a vehicle with lithium-ion technology was ordered for the first time," says Jörg Backhaus, ATEX representative at Stöcklin.

During mechanical testing by an independently accredited specialist laboratory, the accumulator with integrated safety electronics was subjected to intensive tests. These included three axes or positions of "sinusoidal oscillation" and "semi-sinusoidal shock tests". Functional and visual checks were carried out again after each individual test. A final report documents the test results, which were awarded the rating "passed".

As part of the risk assessment for the use of the lithium-ion battery in an industrial truck, including the charging process, potential sources of danger that could pose hazards or stresses were first identified. The criteria included organizational factors, workplace design, ergonomic aspects, mechanical and electrical hazards, fire or explosion hazards such as overcharging or deep discharging of the battery, the effects of water/moisture, dust, low temperatures and much more. Based on this, it was possible to define protective measures that can be used to prevent possible negative effects.

Maturity test under real conditions
The first side-seat stacker with lithium-ion technology developed and supplied by Stöcklin has been in use at Merck in Darmstadt since the end of 2016. "We expect a lot from this purchase," emphasizes Mr. Hoerr. "Long battery life, possibility of intermediate charging, shorter design of individual device groups, elimination of central charging stations through battery charging in production and thus more efficient processes and cost savings. The device has been running successfully for four months and the drivers are happy to use it." Urs Grütter/as