ROSS Pneumatrol manufacture a range of Modular Redundant Control Systems (MRCS) to SIL level 3 (2oo3 / 3oo4 models) to ensure added safety and reliability for process valves used in critical applications. The 2oo3 / 3oo4 range has the patented auto isolation feature which ensures the process valve is always online even when one of the solenoid valves needs replacing.