Fault Finding Guides · Free PDF
On Off and ESD Valve Fault Finding Guide
A one page guide to on off and shutdown valve problems: failure to move, stroke time, limit switches, solenoids and partial stroke testing.
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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 · 51 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
- Air supply and solenoid power present?
- Stroke time within the safety requirement?
- Limit switches set at full open and closed?
- Last proof test result?
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Symptoms, causes and fixes
| Symptom | Likely causes | Checks and fixes |
|---|---|---|
| Does not close on trip | Solenoid stuck, exhaust blocked, seized valve, high friction | Test solenoid; clear vents; stroke test |
| Slow closing | Small solenoid Cv, blocked exhaust, long tubing | Check air path; fit quick exhaust |
| No closed feedback | Limit switch misaligned or failed, cable fault | Adjust cam; test switch; check wiring |
| Partial stroke test fails | Sticking, high breakaway torque, wrong test settings | Full stroke test; inspect actuator and valve |
| Leaks when closed | Seat damage, debris | Leak test; repair seats |
| Solenoid coil fault | Overheating, wrong voltage, water ingress | Check voltage and coil resistance; replace |
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Remember
- Record as found stroke times before maintenance.
- Stroke time must fit within the process safety time.
- A failed proof test needs reporting and review.
Related Tools, Procedures and Calculators
Frequently Asked Questions
Why record stroke time?
A rising stroke time warns of sticking before the valve fails to close.
Does a partial stroke test replace a full test?
No, it detects many failures but not seat leakage or full travel problems.
What closes an ESD valve on trip?
Usually the solenoid vents the actuator and the spring closes the valve.
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