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A bladder tank is a large, flexible container used to store many types of liquids. When maximum capacity is reached, the bladder tank takes the form of a large pillow, hence it is also called a pillow tank.
The first flexible bladder tank was constructed out of polyester and PVC in Alger (Africa) in the 1950s. It was invented by André Labaronne (patent N°1.460.825, 19 October 1965) and marketed under the brand CITAF (Citernes pour l’agriculture Française).
Flexible bladder tanks are made with high resistance PVC material and are welded with high frequency (HF) soldering techniques. The bladder walls are made of polyester with PVC induction. The materials used in bladder walls are generally UV resistant and are chosen for their chemical stability and resistance to mechanical abrasion. Additionally, they are fabricated specifically to allow the tank to stand independent of any external support. Different compositions of bladder walls are used to store different types of liquid. For example, a particular design may be suited for hydrocarbon storage but others could be used for liquid fertilizers, chemical products, rainwater, drinking water, or used water.
Installation of a bladder tank is fast and simple, but requires a large, flat, open surface free of rocks or other materials that might damage the walls. A fine layer of sand or a special ground cloth is often used to minimize surface irregularities. Ground cloths are generally made from a geotextile fabric designed to minimize the chance of abrasion and tank failure.
Bladder tanks are lightweight, flexible, mobile and can last for many years. The materials used to make bladder walls are recyclable and can be re-used for other purposes. Bladder tanks have capacities up to 1,000 cubic meters. Liquid stored in a flexible bladder tank does not evaporate and any odor it may produce is completely sealed within the tank. Contaminants cannot enter a properly sealed tank. Bladder tanks have many practical applications and can be found in agriculture, industry, civil protection, military and humanitarian organisations.