Expansion Tanks With Bladder

Expansion tanks are closed containers usually supplied as pressure vessels that incorporate an internal bladder and charged with Compressed Air. They are designed to allow the gradual Entry & Exit of liquid from the attached system in order to prevent over-pressure or vacuum conditions if the volume of the liquid in the system changes due to temperature, or due to some other effect. Accordingly the inlet/outlet connection requirements are normally very different, with expansion tanks typically requiring much smaller connection than for a similar sized surge vessel. Expansion tanks are normally provided with an internal bladder, or membrane to separate the process liquid from the charged air. Bladders are used because they separate the liquid from the gas and prevent absorption of the gas by the liquid. They also prevent escape of the air from the vessel when the system is depressurised. Internal bladders will be supplied in Butyl, Nitrile or Viton rubbers, depending on the compatibility of the process liquid with the rubber as well as the operating conditions in which the tank will work. Sizing of the vessel will depend upon the demands of the system, as well as the working pressure range and temperature.