Request ProposalRTO Flame Scanner Verification: Prove Burner Safety Signals Before Restart
An RTO can show normal temperature trends while its flame-detection boundary is misaligned, dirty or incorrectly wired. Before a planned restart, verify the flame scanner as a safety instrument—not as a value to be tuned until the burner “looks right.” This guide separates observable evidence from assumptions so owners can release the burner safely.
1. Define the flame-detection boundary
Record burner tag, scanner model, sighting port, flame amplifier and the safety PLC input. Confirm which cabinet, cable and terminal numbers belong to the burner. A marked-up loop drawing and photographs prevent responsibility gaps between burner, controls and RTO suppliers.
2. Inspect sighting hardware and environment
With the burner isolated and cool, inspect the sight glass, purge-air tube, mounting bracket and scanner insertion depth. Look for soot, cracked glass, loose glands, vibration marks and hot surfaces that can distort the signal. Confirm purge air is clean, dry and routed as designed; never defeat a purge to obtain a stronger reading.
3. Prove wiring and signal health
Compare terminal numbers with the approved schematic. Check shield termination, polarity, 24 VDC supply, fuse status and cable segregation from ignition wiring. Capture scanner status, flame-present input, fault output and any analog strength value at the cabinet. A healthy signal must remain attributable to the correct burner and input.
4. Test permissives and trip response
Use the approved commissioning procedure to simulate loss of flame, where permitted. Verify that the safety logic removes fuel, records the correct alarm and requires the intended reset. Check purge-complete, damper position, combustion-air proof and low-fuel-pressure permissives. Do not bypass a trip for production; document test method, witness and restoration.
5. Release criteria and evidence pack
| Check | Evidence to retain | Release question |
|---|---|---|
| Sighting path | Photo, cleanliness note | Can the scanner see the intended flame only? |
| Purge air | Pressure/flow indication and source | Is the lens protected during operation? |
| Wiring | Marked loop and terminal photo | Does the signal land on the correct safety input? |
| Flame loss test | Timestamped alarm/trip record | Does fuel shut off without unsafe delay? |
| Restart permissives | PLC sequence or checklist | Are all gates restored after testing? |
6. Common failure patterns
Intermittent flame signals often trace to a dirty sight glass, loose bracket, poor purge air or shield noise—not immediately to burner instability. A permanently “flame present” input can indicate a shorted circuit or bypass. Treat each as a safety defect until the physical and logic boundaries are proven.
7. Coordinate the restart handover
The handover should name the person who restored each bypass, the exact alarm tested, fuel-valve status, purge status and first-watch readings. Keep the signed checklist with the RTO maintenance record so a later fault can be correlated to a known baseline.
FAQ
How often should an RTO flame scanner be checked?
Follow the burner OEM and site safety-management schedule; inspect after maintenance, refractory work, repeated trips or any sighting-path disturbance.
Can operators clean the scanner while online?
Only if the equipment and site procedure explicitly allow it. Most cleaning requires isolation and verification of the purge and fuel boundary.
Is a flame-strength number alone enough?
No. It must agree with physical sighting, correct wiring, permissives and a documented loss-of-flame trip test.
Professional CTA
Planning an RTO restart or burner service? Contact SERNO to review the flame-scanner boundary, safety I/O and evidence pack before fuel is reintroduced.