DUC - Quick-Mount Clamp-on Ultrasonic Flow Meter for Liquids

The KOBOLD DUC is a clamp-on ultrasonic flow meter for liquids that measures flow from the outside of the pipe, with no contact with the process media. Two clamp-on transducers cover pipe diameters from 3/8 inch to 20 feet and flow velocities to ±98 ft/sec in both directions, with accuracy up to 1% of reading. The meter is offered as the portable, battery powered DUC-MP and as the stationary, wall mounted DUC-MF. Because nothing touches the flow, the DUC is designed for media that might damage the wetted sensors of other technologies and to install without pipe cutting or process shutdown.

How the DUC Measures Flow

The DUC operates on the acoustic time-of-flight principle. Two clamp-on ultrasonic transducers mounted on the pipe exchange acoustic signals through the moving liquid. Flow shortens the transit time of the signal traveling with it and lengthens the return transit time; the transmitter calculates average flow velocity from that difference and the path length.

The transmitter emits a coded signal pattern and uses only received signals that correlate with the original, an evaluation that lets the meter handle media carrying gas bubbles or solids within certain limits. A digital signal processor (DSP) computes the time-of-flight at high sampling rates; the measurement is very precise, drift free, and maintenance free, with no recurring calibrations. Reynolds compensation corrects for media viscosity, and the AFC algorithm adjusts for changing media temperatures without transducer movement.

Portable and Stationary Versions

Two flow transmitters are available. The portable DUC-MP runs approximately 22 hours per battery charge or on line power, includes a 4 GB data logger, and ships in a hard-shell case. The stationary DUC-MF is wall mounted and runs on 90 to 240 VAC, with 18 to 36 VDC optional.

• DUC-MP (portable): one measuring channel, aluminum and ABS housing, IP40 protection, BNC connections, and CSV data files for common office programs.
• DUC-MF (stationary): one or two measuring channels, ABS housing, IP65 protection, screw terminals, plus optional data logger and two optional 4-20 mA inputs.
• 2-channel operation: the DUC-MF 2-channel version measures two points or one common metering point and supports CH1+CH2, CH1-CH2, and (CH1+CH2)/2 operations; opposite mounting is designed to raise accuracy and enable redundancy.

Transducers and Pipe Sizes

Three transducer families match the pipe: the 4 MHz DUC-Wx40 for 3/8 inch to 4 inch pipe, the 1 MHz DUC-Wx10 for 1-1/4 inch to 16 inch pipe, and the 0.5 MHz DUC-Wx05 for 8 inch to 20 foot pipe, each in portable and stationary versions with IP68 protection.

All transducers use PEEK and aluminum construction and operate at media temperatures from -40 to 300 °F (-40 to 149 °C); the portable 0.5 MHz unit is rated to 176 °F (80 °C) with textile tightening straps and to 300 °F with a one-time-use stainless steel strap. V-mode mounting is standard, Z-mode suits large pipes or high acoustic damping, and W-mode serves pipes under 1-1/4 inch. Steel, plastic, and other pipe materials with ultrasonic conductive properties are supported.

Accuracy Across the Measuring Range

Accuracy depends on pipe size and velocity. From 2 inch pipe upward, the DUC measures within ±0.065 ft/sec up to 6.56 ft/sec and within 1% of reading from 6.56 to 98.42 ft/sec. Readings hold 1.5% on 1 to 2 inch pipe and 2.5% on 3/8 to 1 inch pipe in the upper band.

Outputs, Data Logging, and Heat Measurement

Both transmitters provide two 4-20 mA outputs plus pulse, relay, and micro USB connections, along with two Pt100 inputs for heat measurement. The DUC-MF accepts an optional RS232 or RS485 interface, and RS485 supports Modbus communication. Diagnostics include signal strength, SNR, and an oscilloscope display.

With two optional Pt100 sensors measuring feed and return temperatures, the transmitter calculates the thermal output and heat quantity of a heating circuit from temperature difference and flow.

Applications

The DUC serves flow, heat, and verification measurements across the water, energy, and process industries, in permanent installations and portable spot checks. Moving easily between points, it can also be used to check the readings of installed inline flow meters.

• Power plants: cooling water, district heating, pump protection, condensate and boiler feedwater
• Water and wastewater: treatment plant inflow and outflow, drinking water networks, verification of water meters, distribution and consumption, leakage detection
• Facility management: hot and cold water, cooling and air conditioning systems, energy efficiency optimization, pump control
• Chemical and petrochemical: crude and light oil, raw water and wastewater, aggressive and toxic media, thermal oil heat carriers
• Food and beverage: hygienic media measurement, heat volume in energy supply

Cost Advantages on Large Pipes

The DUC is designed to offer a cost advantage on large diameter pipes: it does not require extensive materials, significant shipping costs, or extensive construction and shutdown time to install. For smaller pipes, KOBOLD also offers the DUK compact inline ultrasonic flow meter.

Other Ultrasonic Flow Meter Installation Types

KOBOLD also offers the DUK Compact Inline Ultrasonic Flow Meter that delivers a cost advantage for smaller process pipe diameter applications.

Common Questions