Foam-Water Systems most commonly use the balanced pressure proportioning method for flammable liquid fire protection applications. They are designed to accurately control the flow of a foam liquid concentrate into a water stream over a wide range of flow rates and pressures. Two basic types, bladder tanks and pump systems, require the foam concentrate pressure to be balanced with the water pressure at the proportional which meters the proper amount of foam concentrate into the water stream. The resulting foam solution is piped to discharge devices protecting the hazard area.