Wide Range Proportioner | Model KNR


The wide range proportioner accurately proportions foam concentrate into a water stream over a wide range of system flow rates and is configured to proportion foam concentrate at a 3% ratio. Wide range proportioners are an integral part of an approved foam system. In addition to the wide range proportioner, the main components of the approved foam system are specific foam concentrate(s), a foam storage tank, a concentrate control valve and foam discharge devices.

The discharge devices most commonly used are closed head sprinklers but nozzles, monitors, grate nozzles, foam makers and foam chambers can also be used. The system must be designed so that the wide range proportioner can accurately proportion foam over the range of flow rates expected during the system operation. Intended for use primarily in wet pipe and preaction type systems, the wide range proportioner has the capability to accurately proportion foam concentrate into the water supply at low flow rates as required when only a small quantity of sprinkler heads have activated.

Please refer to specific system manual(s) for further information. This technical data is intended for trained experts. For further information, please contact Fomtec or refer to the technical documentation. The contents of this publication are subject to modifications without notice.

Listings and approvals

FM approved – Low expansion foam systems (FM5130)
The wide range proportioner is FM Approved as part of a fire extinguishing system combining designated foam concentrates, bladder tanks and discharge devices. Approved system components can be found at www.approvalguide.com

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

Wide Range Proportioner | Model KNR

Technical data
Construction features

  • Available in 6” (DN150) and 8” (DN200) sizes
  • Wafer connection for installation between ANSI and PN16 flanges
  • Brass construction
  • Horizontal or vertical installation
  • Direction of flow indicator on body
  • For use with fresh or salt water
  • Identification tag plate

Standard materials

Body, neck, grooved inlet Brass EN CB491K
Rod, clapper, threaded collar Stainless steel
Orifice plate UNS C95800
Spring Stainless steel AISI-302 (DIN 17224)

Ordering information

  1. This wide range proportioner is for use with Fomtec ARC3x3S foam concentrate.
  2. The minimum and maximum flow demand of the fire protection system must be known to ensure correct selection of the wide range proportioner. The required minimum flow rate should be higher than the minimum flow rate shown in table 3.4.1 in the datasheet. The required higher flow rate should be lower than the maximum flow rate shown in table 3.4.1 in the datasheet. 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.
  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

Standard design specifications

Design pressure 250 psi / 17.2 bar (1.7MPa)
Test pressure 500 psi / 34.4 bar (3.4Mpa)
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) (as per FM 5130)
Minimum operating inlet pressure 30 psi / 2.1 bar (0.2MPa)
Maximum operating inlet pressure 175 psi / 12.1 bar (1.2MPa)
Proportioning range See table 3.4.1 in the datasheet

Scope of supply

a) Ensure that all components are complete and in good condition.
b) Check that the tamper proof seal on bottom plug is not damaged or removed. In case of either scenario, reportimmediately to supplier.
c) The wide range proportioner is supplied boxed, with a fixed data plate and an integral sized orifice disc specific to itsapproved/listed foam concentrate.
d) Grooved couplings and flange kits are not included.


Please contact Fomtec for further information.

Product variants

See the datasheet

Performance data

See 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. In addition, the “Authority Having Jurisdiction” (AHJ) may have additional installation requirements that must be followed. Do not alter the piping without consulting a system design representative. Before installing a wide range proportioner, check the system design drawing to ensure the device location does not create excessive head pressure or frictional losses.

Warning: The wide range proportioner must not be installed in dry pipework. If used in preaction, dry or deluge type systems, the wide range proportioner must be installed in the wet pipework upstream of the system control valve.

a) Check that the tamper proof seal on bottom plug is not damaged or removed. In case of either scenario, reportimmediately to supplier.
b) The wide range proportioner must be installed with the arrow pointing in the direction of the water flow.
c) The wide range proportioner can be installed in the vertical or horizontal position.
d) If installed in the system riser, consideration should be given to drainage as the clapper (7) acts as a partial check valvewhich will result in slow drainage. Use of or installation of a drain valve downstream of the wide range proportioner isadvisable for faster drainage.
e) Straight piping equal to a minimum of five (5) pipe diameters should be installed upstream and five (5) downstream of thewide range proportioner to help ensure proportioning accuracy.
f) A removable section of pipe should be installed between the concentrate control valve and wide range proportioner foam inlet to allow the flushing of foam concentrate after system activation.
g) A check valve must be placed on the foam concentrate line and a concentrate control valve is highly recommended.
h) The ideal location for the wide range proportioner is level with or below the top tank discharge point and within 3 feet (1m) of the tank.
i) The wide range proportioner can be placed further from the bladder tank, as long as the pressure of the foam concentrateat the foam inlet of the ratio controller is within 2 psi of the incoming water pressure at low flow rates and 12 psi at maximum flow rates.
j) 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
k) Care should be taken to ensure that the bladder tank and foam concentrate line are vented of trapped air to assist proportioning performance.

Warning: The wide range proportioner must not be adjusted. Security tag is placed on the plug (#8) to prevent unauthorized adjustment.


The wide range proportioner is a modified venturi device for use in bladder tank balanced pressure type proportioning systems. As water flows through the device, 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. The foam orifice size is specific to the foam concentrate used. 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 wide range proportioner can accurately proportion foam concentrate over a wide range of system 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 wide range proportioner must be at or above its low flow rating in order to properly proportion foam concentrate.

Due to the viscosity of some foam concentrates, the low flow rating can be high when using traditional ratio controller style proportioners which makes them unsuitable for closed head wet or preaction sprinkler systems. The wide proportioner is designed to accurately proportion foam at low flow rates when a small number of sprinklers are operating. The proportioning is accomplished by means of a variable geometry concept where the foam concentrate inlet size varies as a function of the sprinkler system’s water flowrate. When water passes through the main waterway as described above, the hinged clapper (7) changes the geometry of the orifice restriction (2) thereby increasing the cross sectional area of the foam inlet The clapper (7) and the orifice restriction (2) progressively open further as the system flowrate increases. At larger water flowrates, the water clapper (7) and the orifice restriction (2) are fully open. (Numbers as per per Fig 6.2.1. in the datasheet).


For details of warranty, contact Fomtec directly.

Inspections, tests and maintenance

Notice: The owner is responsible for maintaining the fire protection system and devices in proper operating condition.

Warning: ny system maintenance or testing that involves placing a control valve or detection system out of service may eliminate the fire protection capabilities 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.


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

Accessories and spare parts

This device is not field repairable and there are no spares parts

Declaration of conformity

If required. Contact us for further assistance.