Pipe disconnector

A system disconnector for physically disconnecting an upstream liquid system with an upstream inlet pressure from a downstream liquid system with a downstream pressure, said upstream and downstream pressures defining a pressure difference, the system disconnector comprising:

• an outlet valve, said outlet valve being adapted to open and close depending on said pressure difference between the upstream and the downstream liquid system;
• an upstream backflow preventer;
• a downstream backflow preventer;
• and
• an outlet valve body in the form of a piston arranged between said upstream and downstream backflow preventers, said outlet valve body moving in an opening and a closing direction;
• wherein
• a space is defined upstream of said upstream backflow preventer, said space being exposed to said inlet pressure of said upstream liquid system;
• a medium pressure space is defined between said outlet valve body and said downstream backflow preventer, said medium pressure space being exposed to a medium pressure;
• a space is defined downstream of said downstream backflow preventer, said space being exposed to said outlet pressure of said downstream liquid system;
• a biasing spring is provided acting in said opening direction of said outlet valve body;
• and
• said pressure difference at said outlet valve body between said inlet pressure and said medium pressure counteracts said biasing spring;
• and wherein
• an actuating member is provided, said actuating member limiting said medium pressure space;
• said actuating member has an upstream and a downstream side, said upstream side being exposed to said inlet pressure and said downstream side being exposed to said medium pressure;
• and
• two stops are provided, said actuating member being adapted to move between said two stops against the power of said biasing spring.