Magnetostrictive Switches

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Magnetostrictive Point Level Switches-Reliable, Solid-State High and Low Level Trips for Critical Protection

Magnetostrictive point level switches provide a simple, highly reliable way to detect when liquid reaches a specific level in a tank, sump, or pipeline. The compact sensor is mounted at the desired trip point and is driven to vibrate at its natural frequency. When liquid covers the sensing tip, the fluid dampens that vibration. The electronics continuously monitor this change and switch an internal relay, delivering a clean, repeatable high- or low-level alarm for pump control, overfill prevention, interlock systems, or shutdown logic.

Because the switch uses a solid-state sensing element with no moving mechanical parts, it is unaffected by splashing, turbulence, or changing product properties. Built-in self-diagnostics continuously monitor the sensor, wiring, and electronics and force the relay to a safe state if any fault is detected. Adjustable time delays filter out nuisance trips from waves or agitation, and rugged enclosures with high pressure ratings allow use across fuels, chemicals, water, and industrial process fluids.

Installation Is Straightforward: The switch threads directly into a nozzle or pipe connection at the required elevation, and the enclosure is wired to AC or DC power with a double-pole, double-throw (DPDT) relay output. Proper orientation, grounding, and cable sealing complete a robust, low-maintenance solution that easily integrates into alarm panels, pump starters, SCADA systems, and API 2350 overfill-prevention architectures.

Cognesense’s magnetostrictive switches combine proven vibrating-element technology with modern diagnostics and hazardous-area approvals. The result is a compact, dependable, and fail-safe point-level switch that plant operators trust wherever accurate, independent level trips are essential.

What Is the Sonac 110?

The Sonac 110 is a single-point magnetostrictive liquid level switch designed for high- or low-level detection and overflow protection in industrial and hazardous applications.
It operates by detecting changes in the vibration of a sealed, stainless-steel diaphragm driven at its resonant frequency — when liquid covers the sensor, the damping effect alters the magnetic signal, which the electronics interpret to actuate a fail-safe relay output.

Why Use a Level Switch VS. a Level Gauge

A level gauge continuously measures and transmits the exact liquid level for inventory management, custody transfer, or process control.

A level switch, by contrast, is a point-level device — it detects whether material is present or absent at a set point and triggers an alarm, pump, or shutdown.

Use a switch when:
  • You only need on/off or high/low level detection rather than continuous measurement.
  • You want redundant overfill protection or a backup alarm for safety systems.
  • The process involves simple automation, such as pump control, inlet starvation alarms, or flow/no-flow detection.

In Short: Gauges Measure; Switches Protect.

A Sonac 110 adds ruggedness and reliability to that protection function.

Applications — Where the Sonac 110 Excels

The Sonac 110 Magnetostrictive Switch is ideal for liquid service in harsh or variable environments where the product is a liquid, including:

Petroleum and Petrochemical Tanks – high-level shutdown and overflow protection for crude, diesel, solvents, and refined products.

Chemical and Pharmaceutical Vessels – accurate level detection despite vapor, foam, or changing dielectric properties.

Pump Sumps, Separators, and Condensate Receivers – reliable low- or high-level alarms even under pressure.

Power and Industrial Plants – boiler feed tanks, cooling systems, or lube oil reservoirs.

Hazardous Locations (Class I, Groups C & D; Class II, Groups E,F, &G) – explosion-proof enclosure options per NEC and NEMA 4/5/7/9/12 ratings.

Its rugged stainless-steel probe handles process pressures up to 2000 PSI and process temperatures from -40 to 220 °F, and its self-testing circuit continuously verifies sensor health — critical in safety-related service.

Sonac 110 — Ultrasonic Level Switch

For plant engineers, maintenance teams, and operations managers who require exact, repeatable switching for interface, high-level, or critical alarm points in challenging process environments.

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Switch Comparison Table

Attribute Sonac 110 (Magnetostrictive Liquid Switch) Sonac 220 (Ultrasonic Bulk/Solids Switch) Microwave 320 (Non-Contact Microwave Switch)
Measurement Principle
Magnetostrictive resonant damping sensor with diaphragm and pickup coil
Ultrasonic acoustic feedback between matched transmitter/receiver sensors (≈38 kHz)
Pulsed X-band microwave (10.525 GHz) transmitter/receiver pair with pulse discrimination
Type
Contact
Contact (non-intrusive for solids; sensors face each other)
Non-contact
Primary Media
Liquids only (crude, refined products, solvents)
Solids, granular materials, fragile products, opaque or transparent objects (≥¼ lb/ft³)
Liquids or solids; detects through non-metallic windows; requires window for metal tanks
Typical Applications
Overflow alarm, high/low liquid level, small vessels/pipes
Bulk solids level, position detection, plugged chute, fragile materials
External level detection, aggressive/hot products, bins/chutes/tanks
Fail-Safe Capability
Self-testing circuit triggers relay on failure
Internal self-test (new PCB)
Selectable fail-safe (high/low)
Operating Temp – Electronics
-40 to 160 °F
Nylon sensor: 220 °F; Ryton: 400 °F
–40 to 160 °F
Operating Temp – Sensor/Process
Liquid-contact diaphragm; temp defined by sensor build
Up to 400 °F for Ryton sensor
Up to 750 °F with high-temperature weldments/sensors
Pressure Rating
Up to 2,000 psig maximum
Not pressure-rated (ambient solids/air-gap use)
Weldment/window dependent; microwave head itself not pressure-rated
Output Type
SPDT relay
Relay output
DPDT relay (5 A @120 VAC; 3 A @240 VAC/24 VDC)
Power Requirements
4-wire electronic switch
AC/DC depending on configuration
115 VAC, 24 VDC, or 230 VAC; 6 VA
Intrusion Into Process
Minimal (<¼″ probe tip)
Non-intrusive to solids (air-gap)
No intrusion
Calibration
Gain + time delay adjustments
Gain + strap adjustments
Gain, time delay, gain select
Signal Path Sensitivities
Damped by liquid contact
Affected by humidity/temperature (auto-adjust frequency)
Response varies with dielectric constant & conductivity
Maintenance
No moving parts; periodic function check
Clean sensors; verify alignment
Align windows; keep path clear
Not Recommended For
Solids, powders, aerated slurries
Heavy slurries/high-viscosity liquids
Direct immersion in liquids
  • Choose Sonac 110 when you need a rugged, intrinsically safe, self-checking liquid switch that tolerates pressure, temperature, and changing product conditions.
  • Choose Sonac 220 or Microwave 320 when dealing with bulk solids or non-contact detection through air gaps or refractory walls.

Why Use the Sonac 110 and Not Another Technology In the Portfolio

The Sonac 110 is purpose-built for critical point detection in liquids — bridging the gap between delicate capacitance sensors and non-contact microwave systems.

Unlike capacitance or RF devices, it does not rely on the liquid’s dielectric constant, so it performs consistently across varying products (crude oil to solvents).
Unlike float-type mechanical switches, it has no moving parts, eliminating wear or sticking.
And unlike ultrasonic or microwave systems, it is compact and self-contained, needing no alignment or external electronics.

In Short

The Sonac 110 is L&J’s go-to magnetostrictive liquid switch when safety, reliability, and simplicity matter more than continuous measurement — the “fail-safe sentinel” for tanks and process vessels.