General
Foam Proportioning refers to the introduction of a foam concentrate into a volume or flowing stream of water. Proper proportioning is essential to ensure the optimum performance from the foam liquid concentrate.
Various types of proportioning systems are available, each with advantages and disadvantages depending on the site conditions and specific application
Premix
The simplest means of proportioning is accomplished by premixing. With this method, pre-measured portions of water and foam concentrate are mixed in a container. In most cases, premixed solutions are discharged from a pressure-rated tank using an inert gas such as carbon dioxide or nitrogen. An alternate method of discharge uses a pump and on-pressure-rated, atmospheric storage tank. The pump transfers the foam solution (under pressure) through piping or hose to the discharge devices.
Inline Inductors (Proportioners)
These are also know as eductors and are probably the most common type of proportioning devices. They are used extensively by municipal and industrial brigades for portable equipment as well as being used in simple fixed systems
Balanced Pressure Proportioning Systems
Balanced Pressure Proportioning is the most common method used for fixed system applications where pressure or flow can vary with demand.There are two basic types – Bladder Tanks and Pump Systems using Balanced Pressure Proportioners.
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