Contrôle & Alarme Tuyauterie Double Enveloppe - pression
The leak detector is connected via the connecting line(s) to the interstitial space(s). The overpressure generated by the pump is measured via a pressure sensor and regulated. When the operating pressure (Pump OFF) is reached the pump is switched off. Due to leaks in the leak detection system which are unavoidable, the pressure will start to slowly rise again. When the switching pressure "Pump ON" is reached the pump is switched on and the system builds operating pressure back up again. During normal operation, the leak detector fluctuates between these two pressure values, with short run-up times and longer standstill times which depend on the tightness and temperature fluctuations of the overall plant.
If a leak occurs on the inside wall or the outside wall then air will escape from the interstitial space. The pressure will drop until the pump is switched on in order to restore operating pressure. If the volumetric flow escaping through the leak is greater than the (limited) delivery rate of the pump then the pressure in the system drops and the pump runs in continuous operation. Any increase in the size of the leak leads to a further pressure loss until eventually the alarm pressure is reached. At this point the system will generate visual, audible and potential-free alarm outputs.