Level sensor technology selection is the first decision and depends on the media, the vessel, and the accuracy requirement. There is no universal level technology — radar excels in steam and dust where ultrasonic struggles, capacitive handles foaming and viscous liquids where ultrasonic and radar may not, and float switches remain simple and reliable where electronic complexity is unwelcome.
Specs to confirm before ordering:
- Function: continuous level transmitter (analog or digital), point-level switch (alarm at fixed point), or multi-point controller (high/low/empty)
- Technology: ultrasonic (non-contact, sensitive to foam and condensation), 80 GHz radar (non-contact, dust/steam tolerant), capacitive (contact or non-contact, conductive or non-conductive media), vibrating fork (point switch, density-tolerant), conductivity (multi-electrode, conductive liquids only), guided-wave radar (rope or rod in the liquid, foam-tolerant)
- Measurement range and accuracy
- Process connection: threaded NPT/G, flanged, sanitary tri-clamp
- Wetted parts: 316SS, Hastelloy, PTFE, PVDF, depending on media
- Process temperature and pressure
- Output: 4–20 mA analog, switch contact, IO-Link, HART, Profibus PA, Foundation Fieldbus
- Hazardous-area certification if needed (ATEX, IECEx, Class I Div 1/2)
- Cable or remote-mount electronics for high-temperature applications
Common gotchas: ultrasonic level transmitters fail on foam — the foam absorbs the acoustic pulse and the sensor reads either empty or wildly fluctuating. Radar sensors require a target large enough to fill the beam at the level; small vessels need careful beam-angle and antenna selection. Capacitive sensors need calibration on the installed media — moving a calibrated sensor to a different liquid usually requires recalibration. Conductivity level controllers work only on conductive liquids; pure water (low TDS) gives unreliable readings.
Typical applications: tank level on water and wastewater treatment, chemical mixing and dosing tanks, bulk-solid level in silos (radar or capacitive), pump dry-run protection (point switch), high-level alarm to prevent overfill, and submersible hydrostatic for well-water level. On legacy installations, in-kind replacement preserves the process connection, mounting depth, and controller scaling.
For obsolete level sensors, send the OEM part number for a sourcing quote.
