Prior to discussing certifications, understanding of the required Safety Integrity Level (SIL) is necessary. SIL levels are not reached by purchasing certificates. In IEC61511-3 it is explained how to determine the required SIL, which then in turn also explains the SIL. The IEC61508-7 B6.6.5 refers to the IEC61025 for the Ball ValvesFault Tree Analysis which I feel show very well what happens when you calculate the PFD of the system you are installing. Then the system PFD should be compared with the required PFD (according to required SIL). 1) A PFD Check Valvesshould be calculated for the complete system and the applicable element only. In order to calculate it the failure rate applicable for your specific situation is required. So the failure rate applicable for: your stroking time, your environment , your fluids , your process . A failure rate from serial test should not be used, field experience should be used. 2) The product certificate shall be issued by an independent authority. Dependent of the required SIL a Butterfly Valvesverification of the complete system shall be performed by an independent authority as well. You shall also read and verify the report yourself for allGate Valves SIL levels. 3) They exist on the market. Some for the bare valve only. So then you don’t know what the combination with the actuator will do and there is oneGlobe Valves with actuator. You could check for large sizes, they are specific design but mainly for SIL2 and above.

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