Foam Ratio Controller – Proportioning Devices | Model KFP


The KCA ratio controller accurately proportions foam concentrate into a water stream over a wide range of water flow rates. The controller proportions foam at concentrations of 1%, 3% or 6%. Ratio controllers are an integral part of an approved foam system. In addition to the ratio controller, the main components of the approved foam system are specific foam concentrates, a foam storage tank, a concentrate control valve and foam discharge devices. The discharge devices most commonly used are sprinklers, nozzles, monitors, grate nozzles, foam makers and foam chambers. The system must be designed so that the ratio controller can accurately proportion foam over the range of flow rates expected during the system operation. Intended for use in wet, dry, deluge, preaction and refrigerated area applications. This technical data is intended for trained experts.

Technical data can be found on the KCA website at The website may include a more recent edition of this technical data sheet. For further information, please contact KCA or refer to the technical documentation.The contents of this publication are subject to modifications without notice.

Listings and approvals

The KCA ratio controller is FM Approved and/or UL Listed as part of a fire extinguishing system combining designated foam concentrates, bladder tanks and discharge devices. Approved and Listed system components can be found at and

  • FM Approved – Low expansion foam systems (FM5130)
  • UL Listed – GHXV.EX26572 (UL162)

Notice: Other international approval certificates may be available upon request.

Foam Ratio Controller - Proportioning Devices | Model KFP

Technical data – Construction features

  • Available in 2” (DN50), 2-1/2” (DN65), 3” (DN80), 4” (DN100), 6” (DN150), 8” (DN200)
  • Brass construction or nickel aluminium bronze construction for superior corrosion protection
  • Horizontal or vertical installation
  • Direction of flow indicator on body
  • For use with fresh or salt water
  • Identification tag plate

Standard materials

Body & nozzle (Nickel aluminum bronze version) Nickel aluminum bronze UNS C95800 - ASTM B148
Orifice (Nickel aluminum bronze version) UNS-C36000 or C46400 or C95800
Fittings (Nickel aluminum bronze version) Stainless steel
Body & nozzle (Brass version) Cast brass UNS C84400 - ASTM B584
Orifice (Brass version) Brass UNS-C36000
Fittings (Brass version) Stainless steel

Technical data – Ordering information

  1. Select the foam concentrate type in table 3.4.1 in the datasheet.
  2. The minimum and maximum flow demand of the sprinkler/deluge system must be known to ensure correct selection of the ratio controller. The required minimum flow rate should be higher than the minimum flow rate shown in table 3.4.1 for the Foam Type selected in Step 1). The required higher flow rate should be lower than the maximum flow rate shown in table 3.4.1. If more than one size of ratio controller is suitable then size selection can then be based on the size of the riser or supply pipework into which the ratio controller will be installed. Note: The flow rates in the FM Approval and UL Listing sometimes differ. Please check the flow range data in table 3.4.1 according to the FM Approval or UL Listing.
  3. After selecting the size, check the appropriate graph in section 7.2.1 to ensure the required flows are possible at the available system pressure. If not, it may be necessary to increase to the next pipe size. Note: Nickel aluminium bronze ratio controllers are standard for EMEA and Asia sales regions and brass is standard for the Americas. Ordering example: A ratio controller is required with a minimum flow rate of 65 GPM and maximum flow rate of 570 GPM using AFFF 3%S foam concentrate in a 3” wet system. The ordering part number is VRC089JAB in EMEA/Asia and F20152B in the Americas.

Ordering example: A ratio controller is required with a minimum flow rate of 65 GPM and maximum flow rate of 570 GPM using AFFF 3%S foam concentrate in a 3” wet system. The ordering part number is VRC089JAB in EMEA/Asia and F20152B in the Americas.

Standard design specifications, all versions

Design pressure 250 PSI / 17.2 bar (1.7MPa)
Design temperature range 14 °F to 120 °F (-10 °C to 49 °C)
Operating temperature range 35 °F to 120 °F (1.7 °C to 49 °C)
Minimum operating inlet pressure 30 psi / 2.1 bar (0.2MPa)
Maximum operating inlet pressure 175 psi / 12.1 bar (1.2MPa)
Proportioning range Refer to table 3.4.1 in the datasheet

Scope of supply

Ensure that all components are complete and in good condition. The ratio controller is supplied boxed, with data plate and an integral sized orifice disc specific to its approved/listed concentrate. Grooved couplings are not included.


Please contact KCA for further information. The product is available directly from KCA and official distributors only.

Product variants


  • Suitable for Fomtec foam concentrate: AFFF 1%S C6 | AFFF 3%S C6 | AFFF 3% M C6 | ARC 3X3S C6 | FP 3% C6 | ENVIRO USP 3% |
    AFFF 6% Ultra
  • Brass UNS C84400 construction available on special request
  • Pre-assembled with bladder tank and water/foam pipe work

See Dimensions and equivalent length-table in the datasheet.


Performance data

See performance data in the datasheet.


Refer to appropriate installation standards (i.e. NFPA, VdS, LPCB, etc.) and / or applicable FM Global Property Loss Prevention Data Sheets such as 4-12, Foam-Water Sprinkler Systems. Do not alter the piping without consulting a system design representative. Before installing a ratio controller, check the system design drawing to ensure the controller location does not create excessive head pressure or frictional losses.

  • The ratio controller must be installed with the arrow pointing in the direction of the water flow
  • The ratio controller can be installed in the vertical or horizontal position
  • Straight piping equal to a minimum of five (5) pipe diameters should be installed before and after the ratio controller to help ensure proportioning accuracy
  • In dry, deluge and preaction systems a removable section of pipe should be installed between the concentrate control valve and ratio controller foam inlet to allow the flushing of foam concentrate after system activation
  • The ideal location for the controller is level or below the top discharge and within 3 feet (1 m) of the tank. The controller can be placed further from the bladder tank, as long as the pressure of the foam concentrate at the foam inlet of the ratio controller is within 2 psi (0.14 bar) of the incoming water pressure
  • The pressure drop within the piping to the bladder tank water or foam concentrate piping can be minimized by:
    1. Limiting the number of tees and elbows used
    2. Using full port valves
    3. Increasing the pipe diameter

A good rule to follow to ensure the piping is designed properly is as follows:

The combined total equivalent length (pipe length plus equivalent lengths for fittings and valves) of the water supply inlet piping and the foam concentrate discharge piping should not exceed 50 equivalent feet (15.2 m). The diameter of this piping must be the same size or larger than the foam concentrate inlet into the ratio controller. KCA requires the installation of a concentrate control valve and a suitable check valve between the bladder tank and ratio controller. This will prevent migration of water into, and foam out of, the bladder tank.


The ratio controller is a modified venturi device. As water flows through the calibrated water nozzle, it creates an area of lower pressure, referred to as the metering pressure drop. As the water flow increases through the venturi, the metering pressure drop increases, allowing more foam concentrate to enter through the sized foam orifice. A decrease in the water flow reduces the metering pressure drop, thereby reducing the foam concentrate flow.

Because the foam concentrate flow changes in direct proportion to the water flow, the ratio controller can accurately proportion foam concentrate over a wide range of water flow rates.

The flow rate at which the metering pressure drop is just high enough to overcome the pressure losses through the bladder tank and its piping, is called the low flow rating. The water flow rate through the ratio controller must be at or above its low flow rating in order to properly proportion foam concentrate.


For details of warranty, refer to KCA’s current list price schedule or contact KCA directly.

Inspection, tests and maintenance

Warning: Any system maintenance or testing that involves placing a control valve or detection system out of service may eliminate the fire protection of that system. Prior to proceeding, notify all Authorities Having Jurisdiction. Consideration should be given to employment of a fire patrol in the affected area.

Refer to respective requirements, according to the relevant standards for inspection, testing and maintenance. If applicable, refer to FM Global Property Loss Prevention Datasheet 4-12 for specific test and commissioning criteria. In addition, the “Authority Having Jurisdiction” (AHJ) may have additional maintenance, testing and inspection requirements that must be followed.


At end of use the product described here should be disposed of via the national recycling system.

Accessories and spare parts


Declaration of conformity

If required, contact Fomtec for further assistance.