Topic
Level
25 guides across the knowledge base.
Wet Well Level Measurement
How lift station wet well level is measured, which technology suits which well, the failure modes that flood a station, and why the high level float must stay hardwired.
8 min readUpdated Sep 5, 2026
Hydrostatic Level Measurement
Measuring level from the pressure of the liquid above a sensor: submersible transducers, bubblers, and base-mounted transmitters, the density assumption behind all of them, venting, installation, and what makes them drift.
8 min readUpdated Sep 5, 2026
Ultrasonic Level Measurement
Non-contact level by time of flight: how the sensor works, the blanking zone and beam angle, temperature compensation, the surfaces and vapors that defeat it, mounting rules, and what to do when it loses its echo.
8 min readUpdated Sep 5, 2026
Float Switches
The oldest level instrument and still the one that saves a station: how tilt and stem floats work, the wiring conventions, mounting and spacing in a wet well, classified-area ratings, and how to use them alongside a continuous instrument.
7 min readUpdated Sep 5, 2026
Open Channel Flow Measurement
Flumes and weirs with a level sensor: how the head-discharge relationship works, Parshall flume and weir equations, where to put the sensor, submergence, and the errors that make a permit-reporting flow meter wrong.
11 min readUpdated Sep 5, 2026
Differential Pressure Level
Measuring level in a closed or pressurized vessel with a DP transmitter: high and low side connections, dry legs and wet legs, zero suppression and elevation, the range calculation with a worked example, remote seals, and the density dependence.
10 min readUpdated Sep 5, 2026
Level Troubleshooting
A method for a level reading that is wrong, frozen, jumping, or lost: establish the true level, check the signal chain and configuration, then the checks for ultrasonic, radar, hydrostatic, DP, and float instruments, and the failure behavior to design in.
10 min readUpdated Sep 5, 2026
Differential Pressure
The differential pressure transmitter as an instrument: what it measures, static and overrange ratings, the three-valve manifold and the order of operations that protects the cell, and the applications from filter head loss to membrane TMP, flow, and level.
9 min readUpdated Sep 5, 2026
Tank Level Control
How a storage tank is filled and drawn on level setpoints, how the setpoints are chosen to keep the water turning over, and what the station does when the tank stops talking.
8 min readUpdated Sep 5, 2026
Lift Station High Level
The alarm that stands between a lift station and an overflow: where the high-level float goes, what it must do on its own, how much response time the well provides, and how to diagnose a high level that should not be happening.
11 min readUpdated Sep 5, 2026
Wet Well Level PID Control
Holding a wet well level with a variable speed pump instead of bang-bang control: the loop structure, the minimum speed floor, the stop and restart logic at low inflow, tuning for a slow integrating process, and where level PID is the wrong idea.
11 min readUpdated Sep 5, 2026
Well Pump Control
Controlling a groundwater well: submersible and line-shaft turbine pumps, the pump-to-waste start, drawdown and the low-water cutoff, cycling limits from the well and the aquifer, and what the controller monitors to protect a pump that cannot be seen.
10 min readUpdated Sep 5, 2026
Elevated Tank Control
The tank on legs that sets the zone pressure: how level equals pressure, the operating band, the altitude valve and its telemetry, turnover for water quality, filling by pumps far away, freeze protection, and what the level signal does when the tank is holding the system together.
10 min readUpdated Sep 5, 2026
Clarifier Control
Primary and secondary clarifiers from the control room: the mechanism drive and its torque protection, sludge blanket measurement and sludge withdrawal control, scum removal, the weir and the effluent turbidity, and the sludge blanket as the early warning for a secondary process losing its footing.
9 min readUpdated Sep 5, 2026
Finished Water Storage
Storage inside the plant: the clearwell that provides contact time and high service suction, backwash supply tanks, and how their levels drive production and pumping. The contact time calculation and the minimum level it demands, water age, and alarms.
9 min readUpdated Sep 5, 2026
Ground Storage Tanks
Controls for ground storage tanks: level measurement and its datum, filling from wells and treatment by pump control or altitude valve, and the telemetry that ties the tank to the system.
8 min readUpdated Sep 5, 2026
Pump Sequencing for Storage
Sequencing the pumps that fill and draw from storage: staging on level bands, rotating wells and sources for even use and water quality, time-of-day and demand-based scheduling, and the records that show the sequence is doing its job.
8 min readUpdated Sep 5, 2026
Constant Speed Pump Control
On and off pumping with constant speed pumps: why it remains the right answer at most lift stations, the level bands and the wet well volume that set the cycle, starts per hour and motor limits, and the cases where variable speed is worth its cost.
8 min readUpdated Sep 5, 2026
How to Configure a Radar Level Transmitter
Commission a non-contact radar on a wet well or tank: mount it, set the reference and range from measured elevations, map false echoes with the vessel empty, set damping and the output, and verify against a tape at two levels before the controller uses it.
9 min readUpdated Sep 5, 2026
Level Reading Jumps
A level that steps, spikes, or flips to a fixed value while the water moves smoothly: the false echoes, foam, turbulence, condensation, cable faults, and controller-side causes behind each pattern, and how to tell them apart from the trend before opening a hatch.
9 min readUpdated Sep 5, 2026
Both Pumps Running Constantly
A duplex station where lead and lag run together and never catch up: inflow beyond one pump, pumps that lost capacity to wear or rags, a force main partly blocked, a pump that runs but does not pump, a level stuck high, or bad setpoints. The drawdown test.
8 min readUpdated Sep 5, 2026
The Tank Level Trend Tells the Whole Story
One trend, a storage tank level over a week, holds most of what an operator needs to know about a water system: demand, source capacity, leaks, pump health, water age, and why it deserves a permanent place on the main screen.
8 min readUpdated Sep 5, 2026
When the Transmitter and the Gauge Disagree
The SCADA screen says 62 psi and the gauge on the pipe says 58, and someone has to decide which one to believe. Why two readings of the same pressure differ, and a procedure for settling the argument with a reference instead of an opinion.
9 min readUpdated Sep 5, 2026
Wet Well Level Control
The measurement that runs a lift station: choosing setpoints, protecting the pumps, validating the signal, and the failures that flood a station.
9 min readUpdated Aug 30, 2026
Radar Level Measurement
Non-contact and guided wave radar, why it handles a wet well better than most alternatives, and the installation details that decide whether it works.
9 min readUpdated Jul 9, 2026
Other topics
Direct contact
Have a controls question?
Reach Eric Sullivan directly about anything on this site, a controls or automation topic, or one of his personal projects.