With a device for influencing the flow, particularly in a horizontal connecting pipe (1) between a coal gasification reactor and a gas cooler/purifier, a solution is supposed to be created, whose task consists in being able to reduce or shut off the gas stream of a hot synthesis gas, if necessary, without being exposed to the great stresses caused by the corrosiveness and the high temperatures, while avoiding complicated valves or regulation devices.This is achieved by means of a Venturi constriction in the flow path of the gas in the pipe (1), as well as a flow cone (4a) positioned on a push rod (4) that is disposed centrally, whereby a connecting rod system (4b) that is guided to the outside is provided to move the push rod (4), whereby the connecting rod system (4b) that moves the push rod (4) is formed by a connecting rod arm guided in a dummy connector and a connecting rod arm guided out of the dummy connector (8) by way of a packed gland (6).