Monitoring vibration on critical rotating plant can play a key role in meeting the protection requirements of the latest machinery directives, specifically (Directive 2006/42/EC) which came into force at the end of 2009. This directive demands that machine manufacturers identify the hazards and risks their products present to users. Any risks identified must be reduced to as low a level as is reasonably practicable.

There are important factors to consider, namely that failure of rotating plant can not only be expensive in terms of repair cost and lost revenue through down-time, but also pose a significant health and safety risk. Also, what level of integrity does a vibration protection system need to ensure safe shutdown under all operational conditions?

To help manufacturers and operators meet these latest protection requirements and to minimise the risks, condition monitoring firm Sensonics has developed vibration protection systems for a variety of industrial sectors. For example its DN2611 SIL (Safety Integrity Level) rated dual channel monitor is well suited for machine casing and bearing vibration monitoring applications. It provides dual level alarms (warning and danger) for each channel and provides a relay interface for plant shutdown and health monitoring.

Current loop outputs for each channel are provided for interfacing with a PLC for trending and further alarm monitoring. The transducer interface can be configured for operation with or without safety barriers. In a simplex configuration the monitor used in conjunction with Sensonics’s PZS4 accelerometer is suitable for SIL 1 applications, while in a duplex configuration (two parallel channels) protection can be provided at a SIL 2 level.

Where the probability of failure to trip on demand for each configuration is designed to meet the SIL target, the resulting spurious trip performance ensures a high integrity protection solution with minimal risk of down-time due to spurious events.