There are several types and brands of proportioning systems on the market. It is beyond the scope of this web site to address the specific details of each system. Sufficient to say for NAF & CAF, the system must deliver the proper amount of the foam concentrate that must be mixed with water at the right concentration (% solution) and volume to make the desired quantity and consistency of BUBBLES for the task at hand. Generally, .3% for CAF, and .5% for NAF.
Proportioners come in two classifications – Manual and Automatic
Manual Proportioners include batch mixing, premix tanks, inline eductors and around the pump eductors. Manual proportioners are generally less expensive than automatic systemms, however, they might require mathmatical skills. Manual proportioners are not automatic and require user interaction during operations. They may require multile adjustments. Some work only on fixed pressures. Some are accurate for only one pressure and one flow. The least expensive way to proportion concentrate is batch mixing, but it requires lots of math on the fly. Manual proportioners are generally used for NAF only applications.
Automatic Proportioners – include Balanced pressure re-circulating, limited re-circulating, and non-recirculating systems; Balanced pressure bladder tanks and electronic controlled direct injection. Many automatic direct injection proportioners monitor the flow of water (via a paddle wheel) and can automatically electronically recalculate the concentrate needed during changes in flow and pressures. Automatic proportioners can have either Non-LED or LED digital display control heads based on the system and manufacturer (brand). Automatic systems can be used for both NAF & CAF and are basically a necessity for CAF.
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Concentrate systems can come in various sizes (volume capabilities) and must be chosen based on the finished foam flow expected/desired. For example, Class A Foam is mixed between .1–1%. That means the system should pump up to 1 gal/min of concentrate for every 100 gal/min (W +Conc) foam flow expected/desired. If a department has a maximum expected/desired flow of 500 gpm of foam, than the proportioner should be capable of flowing a minimum of 5 gpm of concentrate for the expected/desired duration.
The system must also be properly matched to the viscosity of the concentrate desired, or vice versa, purchase concentrate compatible with the concentrate proportioning system chosen. In other words, know the capabilities of the system as well as knowing the details of the concentrate.
Systems are not cheap, so to ensure longevity of operation, follow all manufacturer’s instructions, service as recommended, exercise the system regularly as recommended, train on the proper operations of the system, and purchase good quality concentrate compatible with the system purchased. It is also recommended that maintenance personnel be EVT certified in foam systems.
For specific questions regarding concentrate proportioning systems, consult the manufacturer’s instructions, or utilize the ASK CAF page.
Check the LIBRARY for system ops manuals.
