Fault Finding Guides · Free PDF
Pressure Transmitter Fault Finding Guide
A one page guide to find pressure transmitter faults fast: quick checks, symptoms with likely causes and fixes, and NAMUR NE107 status meanings.
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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 · 53 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
- Loop current matches DCS reading?
- Transmitter display matches process (test gauge)?
- Root valves open, manifold correct?
- Recent work, weather or process change?
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Symptoms, causes and fixes
| Symptom | Likely causes | Checks and fixes |
|---|---|---|
| No output (0 mA) | No loop power, open wire, blown fuse, reversed polarity | Measure supply and terminal voltage; check fuses and polarity |
| Reads high or low constantly | Zero shift, wrong range, head from mounting, blocked tap | Compare with test gauge; check LRV and URV; zero trim at known pressure |
| Reading frozen | Root valve closed, plugged impulse line, fixed current mode | Open and blow down tap; check loop test mode off |
| Noisy reading | Pulsation, gas in liquid line, grounding, low damping | Add damping or snubber; vent lines; check shield grounding |
| Slow response | Long or partly blocked impulse line, high damping, frozen line | Check damping; clear line; check heat tracing |
| Drifts with weather | Blocked vent on gauge sensor, sealed sensor, sun on seal | Clean vent; shade seals; check sensor type |
| Reads after overpressure | Sensor damage beyond overpressure limit | Check zero; replace if outside spec |
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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 does my transmitter read high after mounting?
Liquid in the impulse line adds head; transmitters below the tap read high.
How do I zero a gauge pressure transmitter?
Isolate, vent to atmosphere and use zero trim; never zero against process pressure.
Can a blocked vent cause errors?
Yes, on gauge sensors the reference side must see atmosphere.
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