Content
—Mason Radke
—Autosys, LLC
From: Mason Radke <mason@autosysnet.com>
Date: Wednesday, January 21, 2026 at 8:08 PM
To: Nichols, Jerry <jenichl@countyofsb.org>, Kevin Seifert <kevin@autosysnet.com>
Subject: UF Refinement Notes 1/21/2026
Control System Refinement – PID Tuning, Backwash, and TMP Protection
Today was a focused and highly productive control optimization session centered around improving PID performance, loop coordination, and backwash reliability while preventing nuisance TMP alarms and protecting equipment.
Major Themes
* Improved measurement resolution and control fidelity
* Faster and more responsive PID behavior
* Better coordination between pressure and flow loops
* Stabilized backwash and backpulse behavior
* Reduced false high TMP alarms
* Smoothed transitions and protected mechanical systems
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Completed Work
PID & Loop Improvements
* Updated PV for CONV_PID_N145_60 (P35-4 PID) from integer to float for higher resolution control
* Switched P35-4 PID from Dependent → Independent mode for finer tuning
* Reduced P35-4 update time from 0.5s → 0.1s for faster response
* Retuned FIC-3520-4 PID to P: 0, I: 0.01, D: 0 and monitored trends for overshoot/undershoot
* Added 50 GPM deadband to prevent unnecessary pump hunting near setpoint
* Adjusted unit net flow setpoint from 875 → 825 GPM
* Updated PV for CONV_PID_N145_150 (DP loop) from integer to float for improved small-signal control
* Updated Backwash Flow PID:
* Dependent → Independent
* Update rate 0.5s → 0.1s
* PV integer → float
* Updated Backwash Pressure PID:
* Update rate 0.5s → 0.1s
* Increased P to 5 to better coordinate with flow loop and prevent TMP alarms
________________________________
Backwash & Backpulse Refinement
* Modified Train 4 backwash routine:
* Rung 20: Reduced ramp-down rate from 20/500ms → 4/500ms for smoother decel
* Rung 18: Changed step range from 40–59 → 40–42 to avoid speed overwrite conflicts
* Tuned backpulse startup speed:
* Tested 50% → 48% → 44% → returned to 50% after identifying root cause elsewhere
* Lowered backpulse flow setpoints progressively for TMP protection:
* 1600 → 1400 → 1200 (test condition)
* Adjusted TMP protection behavior:
* Raised High TMP setpoint 7.6 → 8.0
* Increased alarm timer 7s → 15s to avoid false trips during transients
* Tuned both pressure and flow setpoints to:
* Prevent false TMP alarms
* Allow flow loop time to ramp down before protection trips
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Testing & Validation Support
* Temporarily reduced production cycle time 8 min → 5 min to accelerate backwash testing
* Restored production cycle to 8 minutes after validation
________________________________
Additional Logic Enhancements
* In ZW4_NP_FLW routine, Rung 6:
* Forced lower limit speed to 20%
* Ensured proper interaction with Rung 5 logic
* Updated SY_3500_4_SP from 35% → 20% to:
* Allow lower speeds during high TMP
* Match flow PID minimum during chemical backwash
* Prevent pressure PID takeover
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Carryover / To-Do Items
🔧 Engineering Follow-Ups
* Expose FIC_8820_4_SP in the HMI to allow adjustable backpulse flow setpoint
* Review and improve post-production ramp-down logic to prevent hydraulic hammer
* Investigate chemical clean flow control:
* P35-4 uses same flow PID as backwash
* May require separate tuning or gain scheduling for tighter control during chemical clean
—Mason Radke
—Autosys, LLC