STG Heating Pvt. Ltd.

Expansion Bladder Vessels


Expansion tanks are devices designed to absorb the volume change of water or some other liquids, thus allowing the correct operation of a heating plant during all its operative phases.
Elbi produces all the bladders which mounts on its own equipment, as for the production it makes exclusive use of modern injection presses, the most advanced ones in this sector.
All the bladders are tested by the company’s quality control service at the end of the production run.
The accumulator vessel with bladder is a device that, fitted into a pressurised water system, will provide system water at a pre-set, sustained pressure. Its most common application is to supply systems in which the main supply pressure is too low and a pump is fitted to boost the pressure to an acceptable level.
The function of an accumulator vessel is to sustain system pressure by feeding additional water into the system at the required pressure.  This process will limit the number of times the pump needs to start (pump hunting) in order that system pressure remains at the optimum level. The process is achieved by the addition of a pre-charged nitrogen cushion at higher than atmospheric pressure within the vessel shell.This pre-charged cushion is stored between the water bladder and the inner surface of the tank. 
Any water pressure rise (pumping) causes the cushion to be additionally compressed. As system demands arise the nitrogen cushion forces the water from the bladder into the system thus maintaining optimum system pressure. As the retained pressure finally exhausts and system pressure falls a pressure switch will turn the pump on, re-pressurising the system and the accumulator ready for further use. This way the accumulator will prevent the need for the pump to start every time there is a demand on the water system and will flatten the system pressure curve at the optimum pressure.