Any engineers who are involved in machine building as part of their core activities will know all about the EU Machinery Directive 2006/42/EC. Most will have stood in front of a newly built machine performing a risk assessment, trying to pick out potential danger points.
Of course, in identifying any safety risks, one must subsequently design them out or guard against them accordingly. Indeed, the Machinery Directive mandates the keeping of a technical file to show what risk avoidance was implemented to create a safer machine.
Although the directive does not mandate the use of safety-rated products, it clearly differentiates standard components used in a safety application from those built and intended as safety-rated products. The latter are classified separately and subjected to more rigorous requirements, testing and performance expectations.
The directive states that common sense strategies be employed on machinery, such as the use of e-stop buttons and the removal of air in pneumatically operated machines to protect from unexpected movement (where safe to do so).
Some manufacturers specialise in the development of safety-rated components for pneumatic applications. Here at Parker, for example, we have recently developed the P33 safety exhaust valve series, which meets the needs of the Machinery Directive to remove air from machines during either an e-stop or a faulted condition.
When incorporated into an air preparation system, a safety exhaust valve lets you safely and reliably shut-off the pneumatic energy, stopping the flow of compressed air to the machine and allowing downstream pressure to exhaust.
The P33 valve is designed for two-channel control architectures and is externally monitored. Moreover, the valve has a patented fail-safe design that is suitable for use in applications up to Cat 4 PL e. External monitoring gives greater control at the safety device for an application, a feature that also reduces machine complexity with regard to valve start-up or reset functions.
For those seeking further assurances, the P33 ticks all the major criteria associated with specifying a safety exhaust valve, namely: fast exhaust time to faulted condition; fast switching time; utilising series-parallel flow so that both valve elements (redundant design) shift to supply air downstream; high B10 value (life expectancy in switching cycles); and comprehensive monitoring capability to achieve the highest level of diagnostic coverage.
Installing a pneumatic safety exhaust valve, such as the P33, is a simple and cost-effective way to achieve machine safety and comply with the directive. After all, safety allows no room for error. Knowing that products exist which incorporate the needs of the directive and provide an enhanced level of certified safety, brings peace of mind to machinery designers and engineers responsible for enhanced and integrated safety - be safe, not sorry.
If you would like to find out more about Parker’s P33 series of safety exhaust valves and the benefits they can bring to your machine-building projects, please download and read the white paper Selecting & Integrating Pneumatic Safety Exhaust Valves.
Article contributed by Linda Caron, global product manager for Factory Automation, Pneumatic Division.