Master fuel relay

Functional safety relies on active part, not on passive part. For example, a fire resistant door prevents a hazard, but is not safe instrumentation for functional safety. On the contrary, a flame scanner/switch in a utility boiler is an active system as it protects closes the fuel flow and trip master fuel relay in the event of flame failure (through logic). From the previous discussions, it is clear that there is handshaking relationship of SIS with functional safety. These cause effect relationship of functional safety and SIS can be ... 

MFR Master fuel relay (for boiler/fumace systems)... 

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