Walt — Simple Man Takeaway
A level sensor is not measuring what you hope is in the tank. It is measuring what its technology can actually see.
Plain-English Summary
Use this flow when a tank, hopper, bin, or reservoir level signal does not match real material level, causes false full/empty alarms, fails to feed, overfills, or starves a process. Level sensors depend heavily on material behavior, buildup, foam, turbulence, geometry, and sensor type.
R.E.A.L. firstProve process truthCapture before changingCompare field state to logic stateHumans remain authoritative
Sensor / Instrument First-Check Flow
Field Checks
- Sensor technology and application fit
- Safe independent verification of real level
- Foam, dust, bridging, coating, buildup, vapor, waves, turbulence
- Sensor face/probe/float/stilling well/mounting/target zone
- Wiring, power, input card, analog scaling, HMI display
- Setpoints, deadband, damping, filter settings
- Fill/drain rate vs. sensor response
- Venting, pressure, temperature, density changes
- Buildup reading instead of product reading
Watch Out For
- Sensor reading buildup, foam, or bridge instead of product
- Material density or moisture change
- Sensor outrun by fast fill or drain
- False full/empty causing starvation or overfill
- Level value trusted without safe independent verification
- Changing setpoints to hide material behavior
Reverse-Trace / Ghost Busting™ Decision
if level permissive, fill command, pump enable, or transfer-ready logic is blocked.
if the level signal flickers, falsely proves, briefly drops, or only fails during a short fill/drain window.
Recipe / Health Log
Record the good, the bad, and the in-between: real-world condition, sensor state, PLC input state, HMI display, logic use, product/material, method, atmosphere, utility condition, timing, symptom, corrective action, and result.
Related Calculators / S.W.A.T. Screens
Related Handbook / Flows
Walt says STOP! - Safety First
Make these checks prior to proceeding.
Stop and follow site procedures when tanks, hoppers, bins, or vessels contain hazardous material; confined space rules may apply; overfill/spill/pressure/heat/chemical exposure is possible; agitators/pumps/screws/valves/feeders can start automatically; or lockout/tagout is required. Never enter or open vessels without proper procedure and authorization.