Foam System Line Proportioners

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Each CHEMGUARD line proportioner consists of a body, jet, throat, and metering orifice – all of which are corrosion-resistant brass.

The line proportioner body is designed with a female NPT threaded inlet and a male NPT threaded outlet (see Line Proportioner Dimensions). The proportioner body is clearly marked with a flow direction arrow and the designed concentration percentage.

The inlet jet is secured by a stainless steel retaining ring on models CPL-60 through CPL-350; the inlet jet is threaded in place on models CPL-420 through CPL-730. The metering orifice or adjustable metering valve is sized according to the type and percentage of foam concentrate used. The metering orifice is secured with a stainless steel retaining ring to enable ease of change-over to other concentrate percentages.

In fixed systems, the line proportioner may be mounted at a maximum distance of 8 ft (2.4 m) above the minimum foam liquid surface.


CHEMGUARD line proportioners are designed to introduce a controlled flow of foam concentrate into a pressurized water stream. They provide an inexpensive foam proportioning means for systems requiring fixed flow rates and where available water supply pressures are adequate.

Depending on specific foam systems design, line proportioners may operate with inlet pressures as low as 80 psi (5.52 bar). However, in most systems a water pressure between 125 psi and 200 psi (8.62 bar and 13.79 bar) is required. The flow rate and operating pressure required at the foam making device are of primary importance in determining the required line proportioner inlet pressure. The line proportioner must match the flow rate of the foam making discharge device.

CHEMGUARD line proportioners can be used with all types of foam concentrates. The proportioners are available in a wide range of sizes for fixed foam system applications. These applications also require an atmospheric foam concentrate storage tank as shown in the Typical Line Proportioning System schematic.

Typical applications include use by municipal fire departments and CFR type vehicles, or with fixed systems for protecting flammable liquid storage tanks, loading racks, dike areas, and anywhere flammable liquids are used, stored, processed, or transported.