• Clamp-on for pipes from 1/2 to 180in ID
  • Flow range of ±0.1 to 40ft/sec in most applications
  • ±2% of full scale accuracy
    • Requires solids or bubbles of at least 100 microns
    • 75ppm minimum concentration
  • ±0.25% repeatability & ±0.5% linearity
  • 10-digit totalizer
  • Handheld meter with large backlit LCD display
  • Internal battery and/or AC powered
  • Built-in 5-key calibrator
  • 300,000 point data logger
  • USB and 4-20mA output
  • Rugged, watertight carry case

What's in the Box

  • PSE4-A single head ultrasonic sensor
  • 12ft shielded coaxial pair sensor cable
  • Sensor mounting kit for pipes up to 32in
  • Coupling compound
  • Data logger PC software for Windows
  • 1 set of 4-20mA and USB cables
  • Installation and operation manual
  • NIST certificate


The Greyline Instruments, by Pulsar Measurement, PDFM 5.1 doppler flow meter is fast and easy to operate making it ideal for flow troubleshooting, balancing and checking performance of permanent flow meters. The non-contact sensor quickly attaches to the outside of a pipe while the built-in keypad and calibration menu let you set up the instrument in minutes. Use the PDFM 5.1 for projects where a permanent flowmeter is not required or to temporarily replace installed flow transmitters.

The PDFM 5.1 non-intrusive Doppler ultrasonic sensor works with pipes from 1/2" to 180" in diameter. An acoustic pulse is reflected back to the sensor from particles or gases in the flowing liquid. The flow rate of any fluid can be measured as long as it contains air bubbles or solids. It is ideal for wastewater, slurries, sludge, and most chemicals, acids, caustics, and lubrication fluids. The system works with most metal and plastic pipes including PVC, ductile iron, carbon steel and stainless steel.

The PDFM 5.1 is AC/DC powered with built-in NiMH batteries and external charger. With its 4-20mA output you can use the PDFM 5.1 as a spare transmitter in critical applications. For flow studies and troubleshooting, use the built-in 300,000 point data logger. Data logs can be retrieved with the data logging software. Simply connect the USB output directly to your PC or Laptop to download data logger files.