Abstract: A transducer for monitoring the position of movable bodies and in particular for monitoring the position of valve flaps and other elements in connection with systems for fire extinction, is composed of a pipe (4) which is closed at one end and thus forms a hollow body with a bottom (4). The pipe is made of a magnetically inert material and accommodates an inductive sensor (5) of an ordinary type. The sensor is movable inside the pipe, but engages the internal bottom of the pipe in its normal position of use. The transducer is kept in this position by a compression spring (17) which presses against the free end of the cylindrical sensor. With its other end, this compression spring (17) engages a plug (2) at the free end of the pipe. In its position of use, the transducer is arranged such that the bottom of the pipe, and thereby the active face of the sensor, is positioned in the immediate vicinity of the body, e.g. a valve flap, whose position is to be monitored.