RTO Valve Sequencing & Controls Upgrade
Automotive coating facility | Midwest United States | Control modernization to stabilize poppet valve sequencing and restore heat recovery performance.
Challenge
A Midwest automotive coating facility was experiencing frequent RTO shutdowns tied to valve sequencing faults. The existing controls were built around an aging Allen-Bradley SLC-500 with a PanelView 600, and the original sequence no longer gave operators enough diagnostic visibility to separate true valve failures from timing-related nuisance alarms.
In practice, inconsistent poppet valve timing was creating chamber-to-chamber temperature imbalance, uneven ceramic bed loading, and higher-than-expected fuel demand. Maintenance was spending more than 15 hours per month chasing alarms, resetting faults, and verifying air supply issues. With an upcoming stack test on the calendar, the plant needed a reliable controls upgrade that could be engineered, commissioned, and documented without another extended outage.
Solution
VIR Automation completed a controls assessment, mapped the legacy sequence against actual field operation, and migrated the system to a ControlLogix L71 platform. The new PLC program rebuilt the valve sequence around deterministic timers, interlocked permissives, and position-based verification so the controller could confirm each commanded move before the next cycle step executed.
The project also included a new PanelView Plus 7 10-inch HMI with diagnostic screens for valve status, chamber temperature differentials, compressed air health, and alarm history. Historical data logging was added to support compliance documentation, while bed temperature trending gave operators a fast visual indicator of imbalance before it escalated into a trip. During startup, VIR tuned the cycle timing, validated each feedback device, and trained operators and maintenance staff on the new diagnostic workflow.
Optimized PLC Logic
Complete ControlLogix program with reworked poppet valve sequencing, permissives, and fault handling.
Valve Feedback Verification
Automatic confirmation of commanded valve position with clear fault differentiation for timing, air, and feedback issues.
Bed Temperature Trending
Chamber differential monitoring helped operators catch imbalance earlier and protect heat recovery performance.
Compliance Data Logging
Historical operating data was retained for troubleshooting, reporting support, and stack-test preparation.
Results
Shutdowns Eliminated
Valve-related shutdowns dropped from 8 per month to 0 after commissioning.
Maintenance Time Reduced
Troubleshooting time fell from 15+ hours per month to less than 2 hours per month.
Improved Heat Recovery
Fuel consumption decreased by approximately 12% through more stable cycle timing and temperature balance.
Stack Test Readiness
The facility passed its next stack test on the first attempt after the controls upgrade.
Technical Details
Allen-Bradley ControlLogix L71
PanelView Plus 7, 10-inch color touchscreen
64 digital I/O, 24 analog I/O
EtherNet/IP
Allen-Bradley SLC-500 with PanelView 600
Valve position validation, air monitoring, alarm history, compliance logging
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