Signal issues are the primary frustration for technicians working with clamp on ultrasonic flow meters. One minute it’s working, the next minute the signal strength drops to zero.
Use this quick troubleshooting checklist to identify the root cause and get your meter back on track.
Quick Reference: Common Symptoms & Fixes
| Symptom | Likely Cause | Quick Fix |
|---|---|---|
| No Signal (0%) | Dry coupling | Re-apply coupling gel generously |
| Weak Signal (<50%) | Thick paint/rust | Sand pipe surface to bare metal |
| Unstable Reading | Air bubbles | Move transducers to 3 or 9 o’clock position |
| Zero Flow Error | Valve leak | Verify downstream valves are 100% shut |
| Signal Loss | Pipe lining gap | Switch to Z-Method or try a different location |
Detailed Troubleshooting Steps
1. Check Coupling Quality
Symptom: Signal strength slowly degrades over time.
Cause: Coupling gel has dried out or washed away.
Solution:
Remove transducers and clean the face.
Re-apply a fresh layer of acoustic coupling compound.
Ensure the transducers are pressed firmly against the pipe.
2. Verify Pipe Parameters
Symptom: Meter shows signal but reads "0 flow" or wildly incorrect values.
Cause: Incorrect pipe diameter, wall thickness, or material entered in the transmitter.
Solution:
Double-check the pipe OD (Outer Diameter) and wall thickness.
Verify the pipe material (e.g., is it Carbon Steel or Stainless?).
Ensure the correct fluid type is selected (sound speed varies by fluid).
3. Eliminate Air Bubbles
Symptom: Signal fluctuates or drops out intermittently.
Cause: Air bubbles traveling along the top of the pipe interfere with the signal.
Solution:
Never mount transducers at the 12 o’clock position.
Move transducers to the 3 o’clock or 9 o’clock position (side of the pipe).
Ensure the pipe is full of liquid. Clamp on meters cannot measure partially filled pipes.
4. Deal with Old Pipes (Rust & Scale)
Symptom: Weak signal despite good coupling.
Cause: Internal scale or external rust is absorbing the ultrasonic energy.
Solution:
Sand the external surface to bright, bare metal.
Switch from V-Method to Z-Method (Direct Mode) to punch through the scale.
Move to a different section of pipe that might be cleaner.
5. The Lining Problem
Symptom: Absolutely no signal on a lined pipe.
Cause: The liner has delaminated (separated) from the pipe wall, creating an air gap.
Solution:
Try the Z-Method.
If that fails, you must find a section of pipe without a liner or with a bonded liner.
In worst cases, an insertion-type meter may be required.
Still Having Issues?
If you’ve tried everything above and still can’t get a reading, it might be a hardware issue or an application mismatch (e.g., too many particles for transit-time).
Contact our technical support for assistance.
