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Pneumatic products feature safety functions

Festo is launching a number of pneumatics safety products to help automation systems manufacturers comply with Machinery Directive 2006/42/EC. This new directive comes into force on 29th December 2009, and will supersede Machinery Directive 98/37/EC.

Although this is nearly two years away, there will be no transition period – all EU countries are required to incorporate the directive into national law by the end of 2009. Among other things, the directive stipulates various health and safety requirements for the design and construction of machines.

For pneumatically-operated automation, there are four operating states that need to be considered when designing safe systems: commissioning, automatic and manual operation, and emergency functions such as reliable stopping or exhausting. Festo is developing a new range of pneumatics safety products to address each of these areas, to help customers design and build safe automation systems. The first products include clamping units and soft start/quick exhaust valves.

Festo’s new KEC-S clamping unit, and the DNCKE-S cylinder clamping unit, provide a precisely defined braking action, with a choice of 1300, 3200 and 8000N static holding force. The braking action can be initiated by a power failure, pressure failure or drop, or a deliberate output from a safety device. The KEC-S clamping units offer a choice of 16, 20 and 25mm diameter rods.

The braking action is provided by a clamping unit acting on the piston rod under spring force, and can be sustained over long periods. The units are suitable for applications involving varying loads – irrespective of fluctuations in the operating pressure, they have a reproducible and certified actuation time – and they are unaffected by system leaks. Both the KEC-S clamping units and the DNCKE-S cylinders offer a wide choice of mounting options, are approved as holding devices and brakes for use in safety-relevant control systems, and are certified by the BGIA (Occupational Safety and Health Institute). With appropriate additional measures they can also be used for accident prevention in control systems of a higher category.

Festo’s MS6-SV soft-start and exhaust valve will be available in the summer of 2008, and serves as a decentralised/centralised unit for supplying machines and systems with compressed air. It is a self-testing mechatronic system with built-in redundancy; it complies with the requirements of ISO 13849-1. This means that the pneumatic safety measure of reliable exhausting is ensured, even if defects occur within the valve. Furthermore, the safety check of the piston rod position is performed directly by the valve during self-test, which simplifies wiring and installation.

The valve vents the system in critical safety areas in the event of an emergency stop. Exhaust performance amounts to 6000 litres per minute, which is 1.5 times pressurisation performance. The unit can be connected, for example, to a safety door at an assembly station; if an employee opens the cover, the system is exhausted. An additional safety feature, the so-called single-fault safety, is achieved thanks to the unit’s redundant two-channel design – even in the event of a fault, safe exhaust of the system is ensured. Soft-start valves with sensor feedback integrated onto valve terminals are also now available, enabling entire system segments or critical function units to be pressurised slowly and safely.

KEC-S clamping unitand the DNCKE-S cylinder clamping unit

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