Sizing Your System

(Example assumes Single-Point Injection)

Determine maximum and minimum flow and pressure for all foam capable discharges:

Maximum: One deck gun: 500 gpm (1893 l/min) at 150 psi (10.3 bar)
Minimum: One 1-1/2″ line flowing 35 gpm (132 l/min) (mop-up), = 35 gpm (132.5 l/min) at 100 psi (6.9 bar)

Determine maximum and minimum foam concentrate levels to be utilized:

Maximum: 1.0% AFFF
Minimum: 0.5% Class A

Determine size of proportioner to meet requirements:

Maximum Concentrate Requirement = Maximum flow x maximum concentration 500 gpm (1893 l/min) x 1.0% = 5.0 gpm (18.9 l/min)

Minimum Concentrate Requirement = minimum flow x minimum concentration 35 gpm (132.5 l/min) x 0.5% = 0.18 gpm (.68 l/min)

Determine proper plumbing size and FoamPro flowmeter tee to cover range of flows in the first step:

A 3″ diameter pipe will be used to supply these discharges. The 3″ flowmeter will accurately read between 30 gpm (113.6 l/min) and 1150 gpm (4353 l/min). The required range is 35 gpm to 500 gpm (132.5 – 1893 l/min). Therefore, one flowmeter in a 3″ tee will handle the requirements.

If the flows should exceed the capacity of the flowmeter tee, then the installation would require two or more appropriate size flowmeters and a MultiFlo.