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Digital Ultrasonic Flow Meter: Transit Time Non-Invasive External Pipe Probes
Quick Answer
A digital ultrasonic flow meter with transit time non-invasive external pipe probes measures liquid flow from outside the pipe. No pipe cutting, no process shutdown, and no wetted parts. This setup works for clean water, cooling water, desalination fluids, and many chemicals in full pipes.
What It Is
This meter uses two clamp-on probes mounted on the outside of a pipe. One probe transmits an ultrasonic signal downstream. The other transmits upstream. The transmitter measures the difference in travel time. That difference gives flow velocity. The flow computer then calculates volumetric flow based on pipe inside diameter and wall thickness.
Silver Automation Instruments supplies these digital ultrasonic flow meters for pipes from DN15 to DN3000. Standard accuracy is ±1% of reading for pipes above DN50. The device fits carbon steel, stainless steel, ductile iron, PVC, HDPE, and copper. You enter pipe outer diameter, wall thickness, and pipe material into the transmitter.
Why Engineers Choose External Probes
No shutdown is needed. You install the probes under pressure. The process keeps running. This is useful in water treatment plants, district cooling networks, and chemical dosing lines. There are no moving parts. There is no pressure drop. Maintenance stays low because the sensor does not touch the fluid.
In practice, many users first test the meter with a known flow condition. They compare the reading against an installed magnetic or vortex meter. This confirms the signal quality and transducer spacing. We have seen this done on a chilled water header in the Philippines and on a desalination brine line in Oman.
Where It Works Best
Water and wastewater plants use these meters for pump audits, line balancing, and leak checks. HVAC service teams use one portable unit for chiller flow verification. Desalination plants clamp probes on seawater intake, permeate lines, and brine return. Chemical plants measure acids, caustic, and solvents without opening the pipe. Food and beverage plants use the meter for CIP return lines and utility water.
Where It Fails or Gives Bad Readings
The pipe must be full at all times. Gas bubbles and more than 1% to 3% suspended solids weaken the signal. T
For a DN100 pipe, that means 1 m of straight run upstream and 0.5 m downstream. For a DN300 pipe, you need 3 m upstream and 1.5 m downstream. Clean the pipe surface before mounting probes. Apply proper ultrasonic coupling gel. Strap the probes tightly. Check signal strength on the local display.
Outputs and Integration
The transmitter commonly ships with 4-20 mA HART, pulse, and RS485 Modbus RTU. Some models include a data logger and a wall-mount display. Power supply is 24 VDC or 100-240 VAC. Standard probe temperature range is -40 to 180 °C. High temperature probes go higher but need special coupling. The electronics enclosure is IP67 or better. ATEX options are available for Zone 1 and Zone 2 installations.
Selection Checklist
Send us your pipe size (DN), pipe material, wall thickness, fluid type, temperature (°C), pressure (bar), and required outputs. We will select the right probe size and transmitter. For example, a 200 mm stainless steel seawater line at 20 °C and 6 bar can use DN200 clamp-on transducers with 4-20 mA HART output. A 50 mm carbon steel cooling water line at 5 bar may need a small transducer pair and Modbus RS485.
FAQ
Can this meter measure seawater? Yes. The transit time signal passes through seawater. Use this meter on desalination intake and brine return lines.
Does it work on plastic pipes? Yes. HDPE, PVC, and PVDF pipes work if the wall is solid and the pipe is full. Avoid foamed or composite pipe with air pockets.
Can it handle dirty water with solids? Up to 1% to 3% suspended solids is the normal limit. For sludge, slurry, or raw sewage, use a Doppler ultrasonic flow meter instead.
Is pipe shutdown required for installation? No. Installation is non-invasive. You can mount probes while the line is live.
What is the accuracy for small pipes? For DN15 to DN40, accuracy drops compared with DN50 and larger. Expect ±2% to ±3% of reading depending on wall quality and flow profile.
Contact Silver Instruments
Tel +86-25-68650347
Whatsapp +86-25-52155837
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