Cnfirm or correct the understanding of the terms firetested and firesafe; A firetested valve must be operable after the test but need not be seal tight whereas a firesafe valve must fully seal. The reason for my question is a client is requesting a rubber lined firesafe butterfly valve and i need to be 100% certain of the facts before i tell him such an animal does not exist. I see valves marketed as "fire-safe" and "Fire-sealed" Fire-safe valves do not leak to the environment and they have metallic seating elements that limit leakage through the valve after the soft-seats are destroyed by the heat of the fire. You can get fire-safe High-Performance butterfly valves that have a backup metallic seat that takes over after the primary TFE ring goes away. Fire-sealed valves can leak through after a fire but they don't leak to the environment. A rubber-lined butterfly valve would need a graphite stem seal to do this. This is not impossible but unlikely and probably more expensive than using a HPBV. Rubber-lined butterfly valves usually don't have packing, the liner has an interference fit with the shaft and it seals there. Also RLBVs have almost universally, (unwetted) cast Iron bodies that can't take fire-test heat. You'd be looking for an extremely special RLBV where you could get a firesafe HPBV just by checking an option box on the order form. See the Durco BigMax BX2000 as example.

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