| abstract |
This disclosure describes a tank for holding water or other liquid under a selected range of pressure. It comprises a tank with a top opening and means to close and seal the top, with conduit means penetrating the top for the entry and discharge of liquid from the tank. The tank is lined with an impervious flexible cylindrical liner which is closed at the bottom and open at the top and is fastened by sealing over the top opening of the tank. Air or other gas is injected into the tank below the inverting liner so that the liquid is maintained at a pressure equal to that of the gas below the liner. The liner is of larger diameter than the tank, and is held in intimate contact with the tank by the internal pressure of the liquid inside the liner when in the extended position and by the gas pressure when the liner is in the inverted position. In one version a condensible gas such as Freon, of a selected composition is injected into the tank below the level of the liner instead of air or other noncondensible gas. Freon, being a gas condensible at ambient temperatures, can provide a pressure which is substantially constant depending on the temperature, and can vary in volume in accordance with the space provided below the water. |