The invention relates to a gas flow monitor wherein the closing flow has the same value in a plurality of installation positions. According to the invention, the gas flow monitor is further intended to be suitable for small pressure loss values. Design and production are intended to be as simple as possible.The gas flow monitor according to the invention, comprising a gas-tight housing (1) that has a valve seat (4) for an axially movable closing body (10) in the interior that to is held against the direction of flow in the opening position by spring force, is characterized in that the play of said mounting is greater in the open position and continuously narrows upon beginning the closing movement.