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Dynasonics Tfx Ultra Ultrasonic Flow Meter Calibration Steps for Accuracy
Quick Answer: Calibration directly controls the reading accuracy of the Dynasonics Tfx Ultra ultrasonic flow meter. The field calibration sequence should include correct pipe data entry, transducer spacing, zero flow check, signal adjustment, and a final comparison at three flow rates. Silver Automation Instruments supplies clamp-on ultrasonic flow meters with a similar calibration flow and supports these steps for industrial users.
Why Calibration Steps Matter for the Tfx Ultra
Most accuracy errors come from wrong pipe parameters or a skipped zero check. The Dynasonics Tfx Ultra calculates flow from transit time. If wall thickness, pipe material, liner, or fluid temperature is wrong, the flow total shifts. In practice, many operators skip the zero flow check after installation. We have seen this on customer sites many times. A pipe wall thickness error of 1 mm on a DN50 line can shift volume flow by 2 percent or more.
The good news is that you can correct most errors with a field calibration. You do not need a laboratory setup. You need a clean pipe surface, a thickness gauge, a stop watch or reference meter, and stable flow.
Required Data Before You Start
Collect these values before starting the calibration on the Tfx Ultra. Measure pipe outer diameter with a caliper. Measure wall thickness with an ultrasonic thickness gauge. Record pipe material and liner type. Record fluid type and current temperature in °C. If the fluid is water, use sound speed from the meter table. If the fluid is a chemical or oil, enter the specific sound speed from the plant lab or process data.
Check the 4-20 mA HART output loop if you use it for a flow computer or PLC. A wrong current output span will cause the flow computer to see a wrong value even after a correct calibration. Set the 4 mA and 20 mA range before the final flow comparison.
The Tfx Ultra does not need a minimum µS/cm value because it uses sound speed, not conductivity. This is different from magnetic flow meters that require a minimum conductivity.
Step by Step Calibration Process
Step 1: Clean the pipe surface at the transducer locations. Remove rust, paint, scale, and loose coating. Apply a thin layer of acoustic coupling gel. For high temperature pipes above 120 °C, use coupling material rated for that heat.
Step 2: Measure the outer diameter and wall thickness again. Enter these values in the meter menu. Do not trust the original piping drawing alone. Field measurements always beat old drawings.
Step 3: Select the mounting method. Use Z mount for DN50 and below where space is limited. Use V mount for DN50 to DN250. Use W mount for DN15 to DN50 when signal strength is low or the fluid has solids. The Dynasonics Tfx Ultra display shows signal strength. Aim for a value above 60 and a signal quality above 80 percent.
Step 4: Set the transducer spacing to the value calculated by the meter. Then fine tune it by 1 mm or 2 mm while watching the signal. A small movement can lift the signal from 30 to 70 on a clean pipe. Do not lock the transducers until the reading is stable.
Step 5: Run a zero flow check. Close the upstream valve or stop the pump. Wait 2 to 5 minutes until the pipe is full and the flow is completely zero. Read the flow display. If the Tfx Ultra shows a value above or below 0.000, apply the zero offset function. Repeat the check three times.
Step 6: Compare against a reference flow. Start the process at a low flow rate, a mid flow rate, and a high flow rate. Record the Tfx Ultra reading and the reference reading at each point. Adjust the correction factor or K factor until the difference
Step 7: Save the calibration settings. Write down the pipe parameters, signal strength, zero offset, and correction factor. This record helps you restore the settings after maintenance or accidental menu changes.
Field Conditions That Change Calibration
Fluid temperature changes the sound speed. A change from 20 °C to 60 °C shifts the reading if the meter does not compensate. Use a temperature probe or enter the actual process temperature. For pipes with PT100 input, the Tfx Ultra can correct temperature changes automatically. Verify the PT100 reading against a separate surface probe during calibration.
Viscosity and solids affect the signal path. In a paint plant in Southeast Asia, a customer tried to measure solvent with bubbles and viscosity near 2000 cP. The original V mount gave a weak signal. We changed to W mount and increased the sampling time. The reading stabilized after a new zero check and a correction factor of 1.03. That one setup change moved the error from 4 percent to under 1 percent.
For water and wastewater, entrained gas above 10 percent by volume will break the signal. Install the transducers on a vertical or downward pipe section if possible. Avoid downstream of a pump or air release point.
Silver Instruments Clamp On Ultrasonic Flow Meters
For users who need a permanent meter or a second reference unit, Silver Automation Instruments offers a clamp-on ultrasonic flow meter series. The unit supports pipe sizes from DN15 to DN1200, fluid temperatures from -40 °C to 160 °C, and outputs including 4-20 mA HART and RS485 Modbus. An optional PT100 input is available for temperature correction. Some versions carry ATEX Zone 1 certification for gas or petrochemical sites.
The calibration process on the Silver Instruments unit follows a similar pattern. You enter pipe data, check zero, adjust signal, and compare flow at three rates. We can supply a calibration guide with the order and help you size the right meter for your pipe and fluid.
FAQ
How often should I calibrate the Dynasonics Tfx Ultra?
Run a zero check before every critical measurement campaign or every month. Run a full flow comparison every 6 to 12 months or after changing transducers, pipe conditions, or fluid type.
Can I calibrate the Dynasonics Tfx Ultra on site?
Yes. The Tfx Ultra supports field calibration with pipe data, zero offset, and correction factor. You do not need to send the unit to a laboratory for a normal accuracy check.
Which pipe parameter causes the most error?
Wall thickness is the most common source of error. A wrong wall thickness value changes the transit time path and the flow calculation. Measure it with a thickness gauge instead of using drawing values.
Do I need a reference flow meter for every calibration?
A reference helps if you need a correction factor. For zero offset and signal setup, no reference flow is required. For final accuracy verification, use a calibrated inline meter or a volume and stopwatch method at stable flow.
What accuracy can I expect after calibration?
With clean water, a clean pipe, and correct data, a field calibrated Dynasonics Tfx Ultra can hold 0.5 to 1.0 percent of reading. For difficult fluids or old pipes, expect 1 to 2 percent after correction.
Send us your pipe size (DN), wall thickness, fluid type, temperature (°C), flow range (m3/h), and required accuracy. Our engineers will recommend a Silver Instruments clamp-on ultrasonic flow meter with the right mounting method and calibration support.
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