Abstract: A poke hole closure assembly for a gas producer which minimizes the escape of noxious or volatile gas from the producer during a poking operation. The closure includes a block having an aperture therethrough which communicates with a poke hole in a gas producer. A closure plate is hinged to the block to block the aperture and pole hole during normal operating conditions, but is openable to enable a poker to be inserted therethrough to check the fire bed. An inert gas is delivered to a conical nozzle in the aparture to direct the gas into the poke hole, to thereby block the outward passage of noxious or volatile gas from the poke hole when the closure plate is opened. The flow of the inert gas is controlled by a valve which is opened to allow flow upon opening of the closure and is closed to block flow when the closure is sealed.