Patent ID: 7412987

Claim:
An expansion tank system operable to be connected to a pipe system, the expansion tank system comprising: a tank configured to contain a liquid and/or a gas; a connection opening configured to connect the tank to the pipe system; a main channel positioned between the tank and the connection opening; a main valve positioned in the main channel and configured to separate the inside of the tank from the connection opening, the main valve comprising a first valve seat and a first closure member interacting with the first valve seat and being operable: a) to close off the main channel at a defined overpressure when the pressure inside the tank is greater than the pressure in the connection opening, said overpressure having a defined level, and b) to close off the main channel at a defined liquid level in the tank, said overpressure and/or liquid level in the tank closing off the main channel by pressing the first closure member against the first valve seat; an auxiliary channel extending through the first closure member of the main valve from the interior of the tank to the connection opening when the main valve is in a closed position, wherein said expansion tank system is manufactured such that the tank has at least the defined overpressure ex works, the expansion tank system further comprising: an additional valve positioned in the auxiliary channel formed to close off the auxiliary channel, the additional valve being formed to be closed during normal operation of the expansion tank when connected to the pipe system and to be opened when, during operation, a second overpressure exists in the tank greater than the overpressure which exists ex works.