production lines for food, pharmaceuticals, cosmetics and fast-moving consumer goods can now benefit from improved safety protection in explosive manufacturing environments with a new ATEX certified checkweigher designed by Mettler-Toledo Garvens.The innovative XS3 checkweigher offers exceptional weighing sensitivity to minimise the instance of costly product giveaway and an advanced design to comply with European ATEX safety requirements for devices used in areas at risk of explosion. Featuring an anti-static belt conveyor, the checkweigher is also ideal for the inspection of small, lightweight products.
The European Union Directive 94/9/EC (ATEX 95) stipulates essential safety requirements for equipment used in explosion hazard zones, such as those involved in the production of dusty, powdered products or flammable gases and aerosols. These materials can, in the right quantities, and with an appropriate source of ignition, cause an explosion – with serious implications for employee safety and damage to production line equipment. ATEX standards classify such production lines into zones according to the nature and gravity of the explosion risk to specify appropriate devices. Prior to selecting equipment for the line, manufacturers must also ensure they acquire zone confirmation documentation, including all the information necessary to enable suppliers to offer the most appropriate solutions for compliance.
In addition to offering exceptional levels of weighing sensitivity, the XS3 checkweigher has been certified by ATEX assessors as a Category 3 device, making it suitable for use in Zone 2 gassy environments (Category 3G) and Zone 22 (Category 3D) dusty atmospheres. The system’s conveyor belt, designed for the transport of lightweight products, is made from anti-static plastic, which, combined with the conductive stainless steel shell, encasing the conveyor motor and weigh cells, minimises the risk of sparks caused by the build-up of static charge.
The control cabinet – which is one of the three main components of a Mettler-Toledo Garvens checkweigher - has been designed as a hermetically sealed enclosure to avoid any contact of the ambient, potentially explosive atmosphere with the electronic and electric elements protected inside the cabinet. Antistatic materials have also been used in the construction of the operating terminal to further reduce the risk of electrical sparks that could be an ignition source. What is more, special connector feeds for cabling, as well as energy limitation features for switches and sensors, have been developed to maximise explosion protection.
“Each section of the ATEX XS3 checkweigher, including the weighframe, operating terminal and control cabinet has been constructed specifically to meet the strict requirements of the safety standards”, explained Thorsten Germersdorf, Product Manager, Mettler-Toledo Garvens. “In most scenarios only the ‘explosion protected’ weighframe is ever exposed to the explosive atmosphere, with the terminal and cabinet safely isolated, ensuring maximum protection for any machine operatives having to work on the system”.
The HMI and control cabinet can be built to ATEX 3 specifications for use on production lines where the explosion hazard zone cannot be easily isolated. The XS3 checkweigher comes with ATEX documentation, containing a certificate of conformity as well as advice regarding maintenance and requirements for safe machine operation.
A number of additional features can be customised on the XS3 checkweigher to meet the individual needs of the production line and to comply with similar safety guidelines in non-European markets. These include China’s National Supervision and Inspection Centre for Explosion Protection and Safety of Instrumentation (NEPSI), the Korean Occupational Safety and Health Agency (KOSHA) in Korea, and the guidelines of the Factory Mutual Insurance Company (FM Global) in the US. Notified bodies, such as Germany’s Technical Inspection Association (TÜV) and German Motor Vehicle Inspection Association (DEKRA), or Sira Certification in the UK, can be commissioned to carry out independent assessments of conformity. These can be used as a basis for demonstration of compliance with non-European standards.
“The risk of explosion during manufacture is a highly common one, even for food and cosmetic producers, so it is important that they do all they can to minimise the danger for their employees and the potential damage to their machinery”, said Kerstin Bernhart, Marketing Manager, Mettler-Toledo Garvens. “In addition, in a world of increasing production costs, manufacturers, regardless of the industry they operate in, are looking for ways to protect profit margins by reducing wasteful product giveaway. Advanced, sensitive checkweighing technology that meets the rigours of ATEX certification not only enables manufacturers to optimise production line efficiency, but also uphold the highest standards of safety for employees”.
