Fire-safe ventilation valve

摘要

A means and method for assuring a tight sealing closure of a valve in a high temperature condition, such as fire, is provided by an expendable link on the downstream side of the valve stem and an intumescent material and piston on the upstream side of the valve stem so that, at an elevated temperature condition, the expendable link gives way to create a tolerance allowing the piston driven by the expanding intumescent material to shift the valve closure element in the direction of the valve seat to accommodate for any deterioration of the valve seal.