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FWD - Ultrasonic flowmeters for air

Ideal for control compressor, air leakage detection and all air concentration measurement and energy saving

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  • Abundant applicable pipe diameters :
    From Ø25 to Ø200 mm
  • No energy loss due to no pressure loss :
    Measurement principle is ultrasonic method.
    There is no pressure loss without protrusion in the pipe
  • No need of filter such as mist separator thanks to FWD has high resistance to oil mist :
    Accurate, strong and reliable flow rate measurement including with oil mist.
  • Lithium-battery build-in power supply :
    No need of power source installation work by means of battery driven
  • Easy-to-use with all flow convertion formulas :
    The instantaneous flow can be converted to Nm3 / h (flow rate reduced to 0 ° C and atmospheric pressure 101.3 kPa) or standard m3 / h (flow rate reduced to a temperature and pressure defined by user)
  • Capable of forward/reverse measurement and output, flow and alarm repetition

Measurment principle

Two ultrasonic sensors are installed on each side of the flowmeter input and output. When liquid flows (in the direction of the arrow shown on the diagram), difference of transit time by flow velocity occurs between sound waves generated from flow entrance and exit. This time lag is used for detecting the flow velocity of the fluid and calculating the volumetric flow according to cross-section area of the flow meter and flow velocity.
Furthermore, this flowmeter is capable of converting into NORMAL flow rate by means of build-in pressure sensor in the flowmeter.


  • Pipe diameter (mm): 25, 32, 40, 50, 65, 80, 100, 150, 200   
  • Power supply: 24 V DC ±10% or Built-in battery type (battery life : approx.10years at 20˚C)   
  • Power consumption: 24 V DC, 1.5 W or less   
  • Applicable fluids: Air (mainly air factory) or Nitrogen (25-80 mm diameter)   
  • Temperature and humidity of fluid: 10°C to 60°C, RH 90% or less   
  • Working pressure: 0 to 1 MPa (gauge pressure)
  • Flow rate conversion accuracy:  FWD 025–080 : ±2.5% or rate (at 500 kPa, 25°C, dry air)
    FWD 100–200 : ±2.0% or rate (at ≥ 300 kPa)


Main Display

Forward or forward/reverse mode :

  • Ø25–Ø80 mm : Instantaneous flow rate (m3/h) 5-digit (4-digit for over 2000), Pressure (kPa) 5-digit, temperature (°C) 3-digit
  • Ø100–Ø200 mm : Instantaneous flow rate (m3/h) 5-digit (4-digit for over 2000), Pressure (kPa) 5-digit, Temperature (°C) 3-digit

Sub Display

  • Ø25–Ø80 mm: Instantaneous flow rate (Nm3/h) 5-digit (4-digit for over 2000), Pressure (kPa) 5-digit, temperature (°C) 3-digit
  • Ø100–Ø200 mm: Instantaneous flow rate (Nm3/h) 5-digit (4-digit for over 2000), Pressure (kPa) 4-digit, Temperature (°C) 3-digit

Output signal (not available for battery-driven version:

Current output

4–20 mA DC (±0.5% FS), maximum resistance load 400Ω, maximum output current 22 mA
Instantaneous flow rate, pressure, or temperature

Contact output

  • 2 open drain outputs, maximum load 24 V DC, 50 mA, maximum frequency : 10 Hz, Duty 35–65%
  • Output 1: Unit pulse (forward), Output 2 : Unit pulse (reverse), Upper/lower alarm, device error

Connection method:

  • Ø25, Ø32 mm: Ø25 mm : Rc1, Ø32 mm : Rc1-1/4
  • Ø40–Ø80 mm: Wafer (between JIS10K flanges)
  • Ø100–Ø200 mm: JIS10K flange

Materials of gas-contacting parts:

Aluminum alloy, PPS, fluorosilicone rubber, etc.

Installation location:

Indoor or outdoor (IP64 equivalent)

Storage temperature:

-20°C to 70°C, non condensing