Using safety-orientated pneumatics provides the security of implementing safety measures in compliance with the EC machinery directive. Engineers can reliably prevent collisions or uncontrolled restarts after an emergency stop, for example.

At the same time, using safety-orientated pneumatics also minimizes the risk of liability claims.
The EC machinery directive specifies a risk analysis and assessment for machines. Protection goals are derived and defined from this directive. The protection goals are achieved using various safety functions.

For example, safety-orientated pneumatics from Festo, in the form of
• Components
• Circuits
• Engineering
are said to make it easy to achieve safety objectives. Safe operation of machines should be possible in all modes and stages of their service life.

Safety-orientated pneumatics also provide solutions for
• Commissioning
• Automatic/manual operation
• Setting operation
• Risk situations and emergency functions, such as safe stopping, safe exhausting
• Restarting -> protection against unexpected starting up
• Servicing/maintenance

In addition to this, if errors occur, they must not lead to failure of the safety functions, depending on their hazard potential.
In general, the simpler the safety engineering used in the application, the more efficient it is.

The complexity of safety engineering is in the variety of state combinations and transitional states. As a result, it would seem almost impossible to implement standardized safety engineering concepts.

Due to their flexible application, pneumatic drive systems from Festo need to be included in the risk analysis and assessment for each machine, depending on the application.

Festo provides solutions on the basis of risk analyses and assessments for the most common applications. This ensures that the electrical safety functions for your pneumatic system’s controllers are enhanced with the appropriate safety concepts.

Directives are laws. The EC machinery directive applies to mechanical engineering run on.

The primary aim of the EC machinery directive is to specify basic health and safety requirements in relation to the design run on and construction of machines. The CE mark identifies a machine as compliant with the EC machinery directive.

A new machinery directive will apply to the trade in and construction of machines in the EU from the end of 2009.
EU member states urgently have to incorporate this directive into their national legislation because, at European level, directives are laws.

Manufacturers have to comply with the laws of their country.

Applying standards is an option. Standards reflect the best available technology.

Harmonized standards that relate to machine safety serve to reduce safety risks to an acceptable minimum, as per the machinery directive.

The first step is to reduce risk by implementing inherent safety.

The second step is to reduce risk by implementing safety measures. The final measure is to reduce risk through instruction.

Directives and standards describe the process of risk assessment.

Every manufacturer is obliged to carry out a risk assessment. This is followed by a risk evaluation and, if necessary, suitable measures for reducing risk have to be implemented.

During the risk assessment, the hazardous situation also has to be determined and, subsequently, the risks have to be evaluated. This applies to a machine’s entire service life.

The following four operating modes in particular are used for operating a machine:
• Initial position/standstill
• Normal operation
• Set-up and service operation
• Emergency operation

Specific safety functions can be derived from these operation modes:
• Pressurizing of machines
• Maintaining pressure
• Reducing pressure and force
• Exhausting of machines
• Two-hand operation
• Tamper-proof
• Reducing speed
• Free of forces
• Stopping, holding and blocking a movement
• Reversing a movement

You can find these safety functions both in the suggested circuits and in the products and solutions. The information specified always refers to very specific safety functions.

This will enable you to quickly decide whether the information is relevant to your current task, both in the sample circuits and in the products.

Safety is always more than just the hardware and the corresponding circuit diagrams. Safety starts at the concept stage, for example by identifying necessary performance levels.

This article was excerpted from Safety engineering guidelines, available Festo at:
www.festo.com/net/en-ca_ca/SupportPortal/Default.aspx?cat=1186