Abstract: A fire extinguishing sprinkler comprises a support body for supporting a temperature sensitive element provided normally to retain a closure member in position to prevent the flow of fluid through a fluid passage extending through the support body but to permit displacement of the closure member in the event of a fire. The closure member has a sealing surface which extends substantially parallel relative to the direction of fluid flow through the passage to continue to effect a seal during small relative movement between the fluid passage and temperature sensitive element under normal operating conditions.