Ultrasonic measurement for air

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Ultrasonic measurement for air


This ultrasonic flow meter measures flow rate of air or nitrogen gas in pipes with sizes from 25mm to 200mm. 

As an Air flow meter it is ideal for the management of the operating load rate of compressors, the management of the amount of used air in factories and detection of air leakage in factories.

Ideal for:

  • Ideal for control compressor
  • Air leakage detection
  • Visualization of the compressed air use and all air concentration measurement
  • Energy saving.


flowmeter for air on pipe type fwd


Advantages :

  • Easy, quick and economical installation

No wiring work (autonomous battery) or modification of the pipe configuration

  • Clear viewing of compressed air and nitrogen consumption

Fast real-time measurement on large rotating LCD display

  • Early detection of air leaks

Large measurement dynamic and excellent repeatability

  • Measurement data you can trust

Mass flow (Build-in pressure and temperature correction)

  • Maximum flexibility and wide range of applications

Bidirectional ultrasonic technology with no pressure loss

  • Low maintenance

No filter required. High resistance to contaminated fluids.

  • Build to last in harsh industrial environments

Robust and waterproof design


flowmeter for air screwed type wafer type flange type fwd



Measurement principle:flowmeter measurement for air principle type  fwd

Two ultrasonic sensors are installed on each side of the flowmeter input and output. measurement principleWhen 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 supply24 V DC ±10% or Built-in battery type (battery life : approx.10years at 20˚C)
Power consumption24 V DC, 1.5 W or less
Applicable fluidsAir (mainly air factory) or Nitrogen (25-80 mm diameter)
Teperature and humidity of fluid10°C to 60°C, RH 90% or less
Working pressure0 to 1 MPa (gauge pressure)
Range (actual flow rate) and accuracy DiameterRange (m3/h) Accuracy
±2.0% of rate±0.6–3.5 m3/h
25±0.6–35±3.5–35 m3/h±0.6–3.5 m3/h
32±1.1–65±6.5–65 m3/h±1.1–6.5 m3/h
40±1.3–80±8–80 m3/h±1.3–8 m3/h
50±2.5–150±15–150 m3/h±2.5-15m3/h
65±4–240±24–240 m3/h±4–24 m3/h
80±5–300±30–300 m3/h±5–30 m3/h
100±10–500±50–500 m3/h±10–50 m3/h
150±24–1200±120–1200 m3/h±24–120 m3/h
200±40–2000±200–2000 m3/h±40–200 m3/h
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)
DisplayMain 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 ouput4–20 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 methodØ25, Ø32 mmØ25 mm : Rc1, Ø32 mm : Rc1-1/4
Ø40–Ø80 mmWafer (between JIS10K flanges)
Ø100–Ø200 mmJIS10K 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



Ultrasonic measurement for air documentation