Troubleshooting Guides · Free Tool
Level Transmitter Fault Finder
Choose the level symptom for a radar, guided wave radar or DP level transmitter and get the likely causes with checks and fixes.
Radar levelDP levelLost echoWrong level
SymptomLevel reads wrong by a constant offset
Most likely causeWrong tank height or reference point (radar)
First checkCompare configured tank height with the drawing
Causes in order of likelihood
| Cause | How to check | Fix |
|---|---|---|
| Wrong tank height or reference point (radar) | Compare configured tank height with the drawing | Correct the calibration distances |
| Wet leg level changed or evaporated (DP) | Check the wet leg and refill | Refill the wet leg and check LRV and URV |
| Density different from design (DP) | Compare process density with the configured value | Re range for the actual density |
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Before You Start
- Work under a permit, inform the control room and put the loop in manual or bypass the trip before touching a live instrument.
- Compare with a manual dip, sight glass or other independent level.
- For radar, look at the echo curve; for DP, check the impulse lines and wet leg.
- Check that the tank geometry and range in the transmitter match the tank.
Level Transmitter Fault Finder: All Symptoms
Level reads wrong by a constant offset
| Likely cause | How to check | Fix |
|---|---|---|
| Wrong tank height or reference point (radar) | Compare configured tank height with the drawing | Correct the calibration distances |
| Wet leg level changed or evaporated (DP) | Check the wet leg and refill | Refill the wet leg and check LRV and URV |
| Density different from design (DP) | Compare process density with the configured value | Re range for the actual density |
Level stuck, not changing
| Likely cause | How to check | Fix |
|---|---|---|
| Radar tracking a false echo (internals, nozzle) | View the echo curve | Record a false echo map with the tank low |
| Blocked or isolated impulse line (DP) | Check valves and lines | Open valves, clear lines |
| Build up on the antenna or probe | Inspect the antenna or probe | Clean; use air purge or a suitable antenna |
Level jumps or is unstable
| Likely cause | How to check | Fix |
|---|---|---|
| Foam, turbulence or agitator (radar) | Watch the echo amplitude | Use guided wave radar or a stilling well; increase damping |
| Fill stream hitting the radar beam | Check inlet position | Relocate the transmitter away from the fill stream |
| Pressure fluctuations on DP without compensation | Compare with tank pressure | Use a closed tank (wet or dry leg) configuration |
Reads full when tank is not full
| Likely cause | How to check | Fix |
|---|---|---|
| Radar in the blocking (near) distance | Check level against the blocking distance | Raise the nozzle or set maximum level below the blocking zone |
| Condensation or build up near the antenna | Inspect antenna | Clean, insulate the nozzle |
| Wet leg drained (DP closed tank) | Check wet leg | Refill the wet leg |
Lost echo alarm (radar)
| Likely cause | How to check | Fix |
|---|---|---|
| Low dielectric product or heavy foam | Check echo amplitude and threshold | Lower threshold, use guided wave radar |
| Antenna coated or dirty | Inspect antenna | Clean the antenna |
| Tank empty and bottom not visible | Check actual level | Enable empty tank handling setting |
Key insight: for radar, always look at the echo curve before changing settings; it shows immediately whether the transmitter sees the product, an internal or nothing at all.
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Frequently Asked Questions
Why does my radar level transmitter show full?
Often the level is inside the blocking distance, or there is build up or condensation near the antenna.
What is a false echo map?
A stored map of unwanted reflections from tank internals that the transmitter ignores.
Why does DP level read wrong on a closed tank?
Common causes are an incorrect or drained wet leg, or a density different from the design value.
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