Ultrasonic Flowmeter
Product Overview
An Ultrasonic Flowmeter is a non-intrusive flow measurement device that uses ultrasonic sound waves to measure the flow rate of liquids (and in some cases gases). By transmitting and receiving ultrasonic signals through the fluid, the flowmeter determines flow velocity without obstructing the pipe. Ultrasonic flowmeters are valued for their non-contact measurement, zero pressure loss, high accuracy, and ease of installation, making them ideal for water, wastewater, HVAC, energy management, and large-diameter pipe applications.
There are two main types:
- Transit-Time Ultrasonic Flowmeters (clean liquids)
- Doppler Ultrasonic Flowmeters (liquids with solids or bubbles)
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How it works (simple explanation)
Transit-Time Principle (most common):
- Two ultrasonic transducers are mounted on or in the pipe.
- One transducer sends a signal with the flow, the other against the flow.
- The signal traveling with the flow arrives faster than the one going against it.
- The time difference is proportional to the fluid velocity.
- Electronics calculate flow rate and total volume.
Doppler Principle:
- Ultrasonic waves reflect off particles or bubbles in the fluid.
- The frequency shift (Doppler effect) is proportional to flow velocity.
What it measures
- Volumetric flow rate (m³/h, L/s, GPM)
- Totalized flow (cumulative volume)
- Bi-directional flow
- With additional inputs, can calculate energy flow (heating/cooling systems)
Applicable to:
- Clean liquids (transit-time)
- Liquids with solids or air bubbles (Doppler)
Key advantages
- Non-intrusive measurement (clamp-on models)
- No pressure drops and no moving parts
- Minimal maintenance
- Suitable for large pipe diameters
- Wide turndown ratio
- Fast installation without process shutdown
- Works for bi-directional flow
- Long-term measurement stability
Applications
- Water & wastewater – distribution, raw water, effluent
- HVAC & energy systems – chilled water, heating loops
- Oil & gas – non-intrusive liquid measurement
- Chemical industry – process and utility fluids
- Power plants – cooling water and condensate
- Food & beverage – hygienic liquid measurement
- Temporary flow measurement & audits
Installation
Clamp-On Ultrasonic Flowmeters
- No pipe cutting or shutdown required
- Mount transducers externally on the pipe
- Ensure pipe is full of liquid
- Clean pipe surface and apply acoustic coupling gel
- Follow recommended straight pipe runs (typically 10× DN upstream, 5× DN downstream)
Inline Ultrasonic Flowmeters
- Installed directly in the pipeline
- Requires process interruption
- Suitable for permanent, high-accuracy installations
General guidelines:
- Avoid air pockets and excessive vibration
- Correct transducer spacing and alignment are critical
- Vertical installation with upward flow is preferred for liquids
Technical Specifications
Parameter | Specification |
Measurement Principle | Ultrasonic (Transit-Time or Doppler) |
Measured Media | Liquids (clean or with solids, depending on type) |
Pipe Sizes | DN 10 to DN 6000 (clamp-on suitable for very large pipes) |
Flow Velocity Range | 0.01 to 15 m/s |
Accuracy | ±0.5% to ±1.0% of reading (model dependent) |
Repeatability | ±0.2% |
Turndown Ratio | Up to 100:1 |
Operating Temperature | –30 °C to +160 °C (higher with special sensors) |
Operating Pressure | Not limited (clamp-on); inline model dependent |
Output Signals | 4–20 mA, pulse, HART, Modbus, BACnet |
Power Supply | AC, DC, or battery-powered |
Installation Type | Clamp-on, inline, insertion |
Maintenance | Very low |