Fluidwell F124 PID Ratio Controller

The F124 ratio controller has been designed to ensure that two flows are kept at the same ratio even if flows are changing.

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Datasheet F124
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The F124 ratio controller has been designed to ensure that two flows are kept at the same ratio even if flows are changing. The Fluidwell ratio controller will show a strong influence of maintaining a good and constant quality of products and saves money on the blending components. The F124 is a key product of the Fluidwell Process Controller family and is the alternative to replace existing pneumatic controllers in local control loops.

  • Robust IP66, IP67 (NEMA4X) field enclosure. It is so rugged, you can even stand on it!
  • Intrinsically Safe available - ATEX, IECEx, FM and CSA approval for gas and dust applications.
  • Programming can be done by your own crew, with the sensible menu-driven structure, saving cost and irritation. Know one, know them all!
  • Very diverse mounting possibilities: walls, pipes, panels or directly onto outdoor sensors.
Application overview F124


  • Calculates and controls the ratio between flow A and flow B.
    Formula: ratio = additive / main
  • Three control modes:
    - Hand (manual valve control)
    - Local Setpoint (control additive flow only)
    - Ratio (control additive flow to obtain the desired ratio).
  • Bumpless transistion between the control modes.
  • Displays actual and desired ratio simultaneously, flow rate A and flow rate B.
  • Safety mode to place the valve in a safe position
  • Analog output to control the position of the valve.
  • Ratio: seven 17mm (0.67") digits, displayed as percentage.
    Desired ratio: five 8mm (0.31") digits.
  • Flow rate A and B: seven 17mm (0.67") digits.
  • Ratio monitoring: two alarm values can be set: low and high ratio alarm.
  • Displays clear alarm messages.
  • Green LED backlight.
  • Auto backup of settings, setpoint and control mode in EEPROM memory.
  • Operational temperature: -40°C to +80°C (-40°F to 176°F).

Flowmeter Inputs

  • Pulse type inputs:
    Reed-switch, NAMUR, NPN/PNP pulse, Sine wave (coil), active pulse signal.
    Different pulse signal types are allowed for input A and B.
  • (0)4 – 20mA.
  • 0 – 10V DC.

Status Inputs

  • Remote control: Safety mode which stops the control process and places the valve in a safe position.

Pulse Outputs

  • None.

Alarm Outputs

  • Function: Two alarm outputs for low and high ratio alarm.
  • Type: Two passive NPN transistors, active PNP transistors or isolated electro-mechanical relays.

Analog Outputs

  • Function: Control output to position the valve of the additive flow.
  • Type: One passive isolated, floating or loop powered 4 – 20mA output or one active (0)4 – 20mA or 0 – 10V DCoutput.


  • The F-Series is your first and best choice for field mount indicators. Especially in harsh weather conditions like rain, snow, salty atmosphers and temperatures between -40°C up to +80°C (-40°F up to 176°F) for safe and hazardous area applications!
  • Applications where a constant ratio between a main flow and an addititve flow is desired (e.g. applications like glueing, blending or mixing) without the need to manually control the additive flow.
    Alternative basic model: F114.

Power Supply

  • Battery.
  • 4 – 20mA Output loop-powered.
  • 8 – 24V AC/DC.
  • 115 – 230V AC.
  • Basic: 8 - 30V DC

Sensor Supply

  • 3.2, 8.2, 12, 24V DC.

Intrinsically Safe

  • ATEX:
    II 1 G Ex ia IIB/IIC T4 Ga
    II 1 D Ex ia IIIC T100 °C Da IP6X
  • IECEx:
    Ex ia IIC/IIB T4 Ga
    Ex ia IIIC T100 °C Da IP6X

Explosion Proof

  • ATEX: II 2 G EEx d IIB T5

Function: All process data and settings can be read and modified through the communication link.
Protocol: Modbus RTU.
Interface: RS232 / RS485 2-wire or 4-wire / TTL.

LCD example F124
Photo F124

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