Handheld Ultrasonic Flow Meter to Measure the Fluid Velocity of Liquid in a Full/Closed Pipe

The FDT-21 ultrasonic flowmeter from OMEGA is engineered to measure the fluid velocity of liquid either in a full pipe or a closed pipe. This ultrasonic flowmeter is a handheld measurement system which is easy to install and use. It functions based on the difference in the transit time of flight measured, and also establishes the flow velocity by measuring the travel time of a pulse from one transducer to the next transducer.

Compared to the flow in the opposite direction, the flow in the same direction takes less time to travel to the second transducer. Electroacoustic transducers receive and discharge short ultrasonic pulses through the liquid of the pipe. Transducers are arranged vertically at either sides of the measured pipe. Sensors are positioned on the pipe and fixed firmly using a clamp. The display will instantly show the flow velocity. The FDT-21 can be used for plastic, metallic and rubber tubes.

  • Repeatability 0.2%
  • Four-line LCD display
  • Handheld ultrasonic flow meter with a 1% accuracy
  • RS232 output
  • Positive, negative and net totalizer
  • Clamp on transducers


The key specifications of the FDT-21 ultrasonic flowmeter are as follows:

  • Repeatability: 0.2%
  • Response time: 0 to 999 seconds (user configured)
  • Accuracy: ±1% of reading >(0.2 m/s) 0.6 ft/s
  • Velocity: (±0.01 to 30 m/s) ±0.03 to 105 ft/s bi-directional
  • Linearity: 0.5%
  • Pipe size: DN 19 to 100 mm (0.75 to 4") standard [up to DN 6000 mm (236") with optional transducers
  • Temperature range:
    • Standard: 0 to 70 °C (32 to 158 °F)
    • With high temperature transducers: 0 to 160 °C (32 to 320 °F)
  • Transducer frequency: 1 MHz
  • Totalizer: Seven-digit totals for positive, negative and net flow
  • Display: 4 x 16 English letters
  • Liquid types: Most liquids including sea water, clean water, waste water, oil, chemical liquids, crude oil, beer, alcohol and more
  • Suspension concentration: .20,000 ppm (may contain very small amounts of air bubbles)
  • Pipe material: Most plastics, all metals and fiberglass
  • Rate units (user configured): Feet, meter, cubic feet, cubic meter, USA gallon, oil barrel, liter, USA liquid barrel, million USA gallons, imperial liquid barrel
  • Security: Programmable lock-out code
  • Transducer cable length: 5 m (15')
  • Weight: 514 g (1.2 lb)
  • Communications: RS232C (baud rate from 75 to 115,200 bps)
  • Data logger: Built-in, stores over 2000 lines of data
  • Totalizer/calibration: Seven-digit press-to-go for calibration
  • Dimensions: 100 H x 66 W x 20 mm D (3.9 x 2.6 x 0.8")
  • Case: NEMA-4 (IP65)
  • Power: 3 "AAA" Ni-H built-in batteries (included) with 90 to 230 Vac charger, fully charged lasts over 12 hours
  • Housing: ABS plastic with aluminum alloy protective carrying case

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