Device for preventing leakage in pressure ducts

Claim 1

Apparatus for sensing and stopping large and small leakages between one or more tapping locations (6) and a stop valve (2) in an incoming pressurized pipe line (1), including a pressure- and time-controlled regulating unit (4) for opening and closing the stop valve (2), where a pressure sensing means (3) is arranged downstream of the stop valve (2) to give the regulating unit an opening signal when the pressure falls below a given minimum pressure, and where the regulating unit includes time registering means (11,15,18, 22,23,24) for achieving time-controlled closing signals to the valve (2), characterized in that the time registering means is adapted to start an opening time (A) and a total time (B) when the pressure sensing means (3) sends an opening signal and to send a closing signal when the opening time (A) has come to an end, in that the regulating unit (4) simultaneously senses via the pressure sensing means (3) the pressure change during a given first control time (C), in that the total time (B) continues to run if a pressure drop is sensed during the control time (C) but is otherwise broken off, in that the regulating unit (4) blocks sending the opening signals further to the stop valve (2) when the total time (B) has come to an end, and in that the regulating unit (4) has means (23-27) for sensing the number of opening signals from the pressure sensing means (3) during a given longer monitoring time (D) such that if certain given signal conditions are met there is achieved a signal indicating leakage.