Ultrasonic Flow Meters

The non-contact ultrasonic flow meter is a non-invasive flow meter available in two formats: transit time and doppler. Both technologies feature clamp on designs with transducer arrangements that can detect in-situ flow rates from outside the pipework, without any interruption to flow or process. RS Hydro offer an extensive range of ultrasonic flow meters for sale and rental. The use of non-invasive, ultrasonic flow measurement offers great benefits in many applications. By using ultrasonic transducers clamped to the outside of pipework, there is no downtime or disruption. RS Hydro offer installation, maintenance, calibration & rental of ultrasonic flowmeters.

Fixed - Clamp-on Ultrasonic

Fixed - Clamp-on Ultrasonic

Fixed installation ultrasonic flowmeters with clamp-on, spool piece or wetted transducers suitable for pipes ranging 12-8000mm. We also supply the AT868 and DF868 ultrasonic flow meters with MCERTS certification. Most of permanent ultrasonic flow meters are in stock.

Fixed Ultrasonic Flowmeters >>

Fixed - Inline Ultrasonic

Fixed - Inline Ultrasonic

Inline and insertion ultrasonic flowmeters that use ultrasonic flow measurement technology, featuring the industry leading SITRANS range of transit time flowmeters from

Inline Ultrasonic Flowmeters >>

Fixed - Hazardous Area

Fixed - Hazardous Area

Ultrasonic flow meters suitable for hazardous area applications including offshore platforms and zone 2 areas. Our intrinsically safe flowmeters are extremely rugged and can be used for measuring almost any liquid.

Hazardous Area Flowmeters >>
Portable Ultrasonic Flow Meters

Portable Ultrasonic Flow Meters

RS Hydro supply the very latest ultrasonic flow meters, which can measure liquids up to 400ºC , can be used with most pipe materials and linings and on pipes from 10mm to 8000mm diameter. Our portable flow meters require minimal installation & training and can provide flow measurement readings within minutes. Our ultrasonic flow meters are available off the shelf - purchase or rental...

View Portable Ultrasonic Flowmeters >>

Transit time flow meters, or also known as 'time of flight' flow meters are mainly consigned to the measurement of clean liquids, although many flow measurement devices have a maximum tolerance of 5% solids. The principle behind this type of non-intrusive clamp-on (strap on) flow meter is that acoustic waves with a frequency of >20kHz are emitted from one transducer to the other side of the pipe back to the opposite transducer requires less time than when travelling in the opposite direction. The differential transit time of the synchronised signals is proportional to the flow rate of the fluid. Doppler flow meters using accoustic attenuation caused by the reflection of ultrasound signals from particles or gas bubbles within the liquid. Doppler ultrasonic flow meters are regarded as an old technology offering much poorer accuracies than transit time flow meters.

Panametrics Portable PT878 and PT868 Ultrasonic Flow Meters

The GE Panametrics PT868 and PT878 ultrasonic flow meters are designed to withstand rugged use in industrial applications. With superior diagnostics, functionality and accuracy this flow meter is regarded as leading edge technology. The PT878 utilises an acoustic signal-coding technique to make accurate measurements in flows containing gas bubbles or entrained solids. We would recommend this flow meter to professionals who want the most from a portable ultrasonic flow meter. This meter has two external inputs which makes it ideal for a heat metering survey.

Advantages of Clamp-On Flowmeters

  • Non-invasive flow monitoring
  • Measurement of non-conductive fluids
  • Easily installed clamp-on sensors with no interruption to flow
  • Wide range of pipe materials and sizes: 12.7-7600mm
  • Process temperatures from -40°C to 200 °C
  • Integrated wall thickness measurement

Comparison of Ultrasonic vs Other Types of Meter

Meter Type



Able to measure flow in medium and large pipe sizes


less intrusive
low flow capability


can measure gas, steam & non-conductive liquids


less intrusive little or no pressure drop less need for recalibration


less intrusive; not subject to wear - no moving parts


Applications for Ultrasonic Flow Monitoring

Ultrasonic flow meters can measure almost all light homogeneous fluids including water, wastewater (<5% solids) and hydrocarbons. The basic requirement is that the fluid can conduct ultrasound and have an acceptable axis-symmetrical flow. Click here to see the many fluids that ultrasonic devices can measure.

Typical applications include:

  • Water distribution flow metering
  • Leak Detection
  • Wastewater flow-metering
  • Building Services
  • Inspection of fixed installation meters
  • Power/Energy Management
  • Chemical / Pharmaceutical
  • Petro-Chemical
  • Pump inspection
  • Food/Hygienic flow-monitoring
  • Steel
  • Light Industrial
  • Survey work

Ultrasonic Flowmeter Specifications

Although specifications are different between the various manufacturers, the following is intended as a guideline to ultrasonic flow meter performance and specification.

Flow Range

0.01-20m/sec (Bi-Directional)


±0.5-3% of reading


Typically ±0.5%

Pipe Size


Operating Temperature



-40°C to +200°C


-10°C to 50°C


Typically>100,000 data points, time stamped


4-20mA, pulse


Built-in battery with external 12v input, 8-36 hours operation


Typically 250 x 150 x 40mm

Weight (Control Unit)

Typically 3-5lbs (1-2kg)


Ultrasonic Flow Meters : General Flow Meter Installation Requirements

For optimum accuracy the following conditions must apply:




>10 diameters of straight-length pipework should exist upstream of the measurement point, & 5D downstream. Ideally these distances should be longer.

Wall Thickness

For optimum accuracy, the pipe wall thickness should also be measured. Some meters are supplied with ultrasonic wall thickness gauge

Liquid Medium

It is essential that the type of fluid is known. Also that there are no air bubbles and that the solid content does not exceed 5%.

Pipe Condition

The pipe wall exterior should be free from dirt, paint or corrosion. For optimum accuracy the interior wall should also be free from deposits or corrosion.


RS Hydro Facebook RS Hydro Twitter RS Hydro Youtube RS Hydro RSS Feeds