Bladder tanks are positive displacement proportional systems made of a tank and an in-line mixer. The tank is equipped with a bladder which is used to store the foam concentrate and the mixer is piped directly into the bladder tank. During operation, water flows into the mixer and creates a pressure difference. This pressure drop along with membrane compression allows foam concentrate to be injected into the water stream.

This system works until the foam concentrate stored inside the membrane is exhausted and the tank is filled with water. Bladder tanks can be equipped with two types of mixers named type A and type B. Type A is a standard foam proportioner that allows a constant mixing ratio over a 1:6 water flow rate range. Type B is instead a mixer, also known as a wide ratio, and therefore can operate over a wider flow range.

Bladder tanks are manufactured according to ASME or EN standards with variable thicknesses according to customer requirements for design pressure and allowable corrosion. Each unit is available in a horizontal (PSLO) or vertical (PSLV) configuration and according to customer specifications including accessories such as: dual tank system (2xPSLV), ladder for easy access to hole(s), flood or road control The round is customized. Valves for foam system automation, manual or electric filling pumps, sliding platforms and special painting methods.

The bladder reservoir can also be made with foam concentrate to fit inside (SIM) or outside (SEM) the bladder.