Fault Finding Guides · Free PDF
DP Level and Guided Wave Radar Fault Finding Guide
A one page guide to DP and guided wave radar level problems: density changes, wet legs and seals, ranges, interface and probe coating.
One page A4Vendor neutralFree, no sign up
Download
A one page A4 guide to print for the workshop or keep on your phone in the field. The full content is also shown below.
Download PDF A4 · 56 KBBefore you start
- Permit, isolation and control room informed.
- Put the loop in manual or inhibit trips as authorised.
- Use certified test equipment in hazardous areas.
- Record as found readings before changing anything.
Quick checks
- Wet legs full, seals intact?
- Density used in range matches product?
- GWR echo curve saved?
- Compare with gauge glass or dip.
Advertisement
Symptoms, causes and fixes
| Symptom | Likely causes | Checks and fixes |
|---|---|---|
| DP level reads high | Wet leg partly empty, higher density, blocked LP | Refill leg; check density; clear LP tap |
| DP level reads low | Lower density, gas in HP line, blocked HP | Check density; vent HP; clear tap |
| Drift with ambient | Remote seal capillaries in sun, unequal lengths | Shade and insulate capillaries |
| Wrong after product change | Range calculated for old density | Recalculate LRV and URV |
| GWR reads end of probe | Low dielectric, coating, wrong probe length | Check dielectric and probe settings |
| GWR interface wrong | Emulsion layer, wrong upper dielectric | Check settings; sample to confirm layers |
Advertisement
Formulas
- h = ΔP ÷ (ρ g).
- Wet leg offset = ρleg g Hleg.
- 1 m water ≈ 98.07 mbar.
NAMUR NE107 status
| Status | Meaning | Action |
|---|---|---|
| F Failure | Output invalid | Repair or replace; check loop goes to safe state |
| C Function check | Simulation, calibration or maintenance active | Finish the work, return to normal mode |
| S Out of specification | Operating outside limits or uncertain | Check process conditions and sensor |
| M Maintenance required | Still valid but degrading | Plan maintenance before failure |
Related Tools, Procedures and Calculators
Frequently Asked Questions
Why is my level wrong after a product change?
DP level depends on density; recalculate the range.
Why do seals drift in sun?
Fill fluid expands unequally in the capillaries.
What dielectric does GWR need?
It depends on probe type; coaxial probes handle the lowest values.
You May Also Like
Learn more on the blog
DP level transmitter calibration: zero suppression and zero elevation
A practical guide on instrumentationblog.in with more background on this equipment.
Read Full ArticleMore Fault Finding Guides
Pressure Transmitter Fault Finding GuidePrintable A4 PDFDP Flow Measurement Fault Finding GuidePrintable A4 PDFMagnetic Flowmeter Fault Finding GuidePrintable A4 PDFCoriolis Flowmeter Fault Finding GuidePrintable A4 PDFVortex and Ultrasonic Flowmeter Fault Finding GuidePrintable A4 PDFRadar and Ultrasonic Level Fault Finding GuidePrintable A4 PDFTemperature Measurement Fault Finding GuidePrintable A4 PDFControl Valve and Positioner Fault Finding GuidePrintable A4 PDFOn Off and ESD Valve Fault Finding GuidePrintable A4 PDFpH and Conductivity Analyser Fault Finding GuidePrintable A4 PDFFixed Gas Detector Fault Finding GuidePrintable A4 PDFPLC Analog Input Fault Finding GuidePrintable A4 PDFModbus and HART Communication Fault Finding GuidePrintable A4 PDFVFD Fault Finding Guide (Vendor Neutral)Printable A4 PDFNAMUR NE107 Diagnostic Status GuidePrintable A4 PDF
Advertisement