27. July 2012

Determination of MTTFd values according to EN ISO 13849 for Pneumatically-Operated Relief Valves

Category News

With the commencement of the new safety guideline for the machine and plant manufacture 2006/42/EG, machine and plant control systems have to be evaluated in accordance with their degree of reliability.

According to DIN EN ISO 13849 safety-related machine control systems are divided in different "performance level" (PL). For this purpose MTTFd values (mean time to dangerous failure) are required for each single component of the machine.

For hydraulic valves installed into safety related controls the following is required:

• Automatic achievement of the normal position at power loss
• Safe holding of the normal position

In the norm a dangerous failure is defined as failure malfunction in terms of the intended use. The operation instruction of the pneumatically-operated relief valves defines the intended use as: "The valve is to be exclusively used to relieve pressure from bearing parts in machines."

Maximator has proven its pneumatically-operated relief valves with respect to all relevant "basic" and "proven" design principles, and also implemented improvements in the manufacturing process of the relief valves.

For the designated application defined within the intended use, the determined MTTFd-values are absolutely reliable and technically well-founded. Our specialists will advise you competently and reliably on the subject of machine safety and are at your disposal for any further information.