Abstract: The procedure for monitoring leakage of incompressible fluid includes introducing a predetermined volume of testing fluid into a conduit system at a pressure about the same as that at the source of the pressurized fluid during a testing period when no fluid is being withdrawn from the conduit system and flow from the fluid source is blocked and measuring the time required for the predetermined volume to flow into the conduit system. The apparatus includes a cylinder connected in parallel with the main valve between the source and the conduit system, a movable wall in the cylinder to divide it into two chambers and a spring in the chamber for urging the wall from the conduit system side chamber together with control apparatus for sensing the volume of the last mentioned chamber decreasing to a preselected volume. The control apparatus also includes mechanism for opening and closing the main valve and monitors large and/or small leakage occurrences.

Abstract: The apparatus functions for monitoring small leakages in order to activate an alarm in the event that there has been more than a predetermined volume of small leakage through the water taps or other part of the system and to automatically turn off a main valve if flow continues therethrough more than a predetermined time and will allow the main valve to open if the discharge of fluid is temporary stopped. The system includes a main valve having a valve seat and a shunt circuit that bridges the valve seat. The shunt circuit includes a volume flow meter and a shunt valve for blocking fluid flow through the circuit. The main valve opens only when the volume in the shunt path exceeds a predetermined value. The shunt circuit includes a throttle that when fluid flows therethrough, provides a pressure drop in the shunt circuit which results in the main valve diaphragm opening when the shunt circuit predetermined value is exceeded.

Abstract: The method and apparatus is directed to monitoring a fluid conduit system for leaks, particularly a leakage flow of less than 25 liters per hour. After closing a main valve that fluidly connects a fluid source to the conduit system, the time is measured for the pressure in the conduit system to drop to a predetermined first value. Upon reaching the first value a shunt valve is opened and the time is measured for the pressure to rise to a second predetermined value. The leakage flow is calculated from the two measured times and the two pressures together with known constants for the control system. In place of providing the shunt valve the main valve may be partially opened. Controls for the valves are provided together with evaluating apparatus for determining the leakage volume.