Magnetostrictive Level Gauges

MCG 8150B, MCG 8151, MCG 1010M

Sealed-probe precision for level and interface.

What It Is & How It Works

A magnetostrictive level gauge uses a sealed stainless-steel probe inserted vertically into a tank, with one or two magnetic floats riding on the liquid surface. The transmitter sends a brief electrical pulse down a waveguide wire inside the probe. Where the pulse encounters a float’s magnetic field, it generates a torsional wave that travels back to the electronics. By timing that return signal with microsecond resolution, the system determines the exact float position and reports continuous level data with typical accuracy of ±0.001 inches.

Because the measurement is based on time-of-flight along a fixed waveguide, magnetostrictive gauges deliver exceptional long-term stability with no recalibration drift. They are unaffected by changes in dielectric constant, density, or vapor conditions. A second float can simultaneously track a product/water interface, and integrated RTD elements report temperature at multiple heights along the probe, delivering level, interface, and temperature data from a single instrument.

The probe mounts vertically through a tank nozzle or inside a stilling well. A single float measures product level; adding a second float enables simultaneous interface or water content detection. Each float is weighted to match the product it tracks, ensuring it rides at the correct position on the liquid surface. Floats are available in multiple pressure ratings to suit both atmospheric and pressurized tank applications. Proper vertical alignment and clearance inside the riser ensure free float travel across the full measurement range.

Magnetostrictive vs. Servo Level Gauges

Both technologies provide high-accuracy continuous level measurement, but they serve different tank environments. Servo gauges use a wire-suspended displacer to measure level, density, and temperature on large above-ground tanks, with custody-transfer-grade density profiling for fiscal measurement. Magnetostrictive gauges use a sealed probe with magnetic floats, excelling in underground, pressurized, or confined installations where a sealed, no-moving-parts design is essential. Servo measures density directly; magnetostrictive detects liquid interfaces.

Choose servo level gagues for fiscal measurement on above-ground tanks where you need density and/or BS&W measurement.

Choose magnetostrictive level gauges for sealed-probe precision in pressurized and underground installations.

When to Choose Magnetostrictive Level Gauges

Magnetostrictive gauges are the right choice when sealed-probe construction, long-term measurement stability, and simultaneous level and interface detection are priorities.

Underground Storage Tanks Precise product and water-interface monitoring at terminals, refineries, and fueling stations, supporting leak prevention and EPA SPCC compliance.
Pressurized Spheres & Bullets LPG, ammonia, butane, or propylene storage where sealed probe construction handles high pressure and hazardous atmospheres safely.
Separator Vessels & Process Tanks Oil/water or multi-phase interface detection critical to product quality, where dual-float configuration reports both levels from one instrument.
Refined Product & Chemical Storage Continuous level and interface data under varying vapor or temperature conditions, with accuracy independent of product changes.
Hazardous & Classified Areas FM, ATEX, and IECEx approved installations requiring certified instrumentation and digital communication in explosive atmospheres.

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MCG 8150B, MCG 8151, MCG 1010M

Why It Excels

Underground or confined installations

Sealed probe design with no external moving parts operates safely in buried, high-pressure, or access-limited tanks.

Applications requiring simultaneous level and interface data

Dual-float configuration reports product level and water bottom from one probe, eliminating the need for separate instruments.

Tanks with varying product types or changing density

Time-of-flight measurement is independent of dielectric constant, density, and vapor composition, maintaining accuracy across product changes.

Facilities prioritizing long-term measurement stability

Absolute position measurement along a fixed waveguide does not drift over time, reducing maintenance and recalibration burden.

Process tanks requiring integrated temperature profiling

Built-in RTD elements along the probe length report temperature at multiple heights for stratification monitoring and volume correction.

What to Consider Alongside Magnetostrictive Level Gauges

Consider an alternative when:

You need custody-transfer-grade density measurement and direct mechanical surface reference on large above-ground tanks. See our Servo Level Gauges.
The application calls for non-contact, maintenance-free measurement with no probe in the liquid. See our Radar Level Gauges.
You need a power-free mechanical gauge with visual indication at the tank. See our Float & Tape Level Gauges.
You need only point-level alarms rather than continuous measurement. See our Level Alarms.

How this technology fits into a larger system:

Pair with a Radar Gauge as an independent non-contact level reference on the same tank, providing electronic dual-measurement compliance under API 2350 and OIML R85. See our Radar Level Gauges.
Add MCG 1090/1095 Level Alarm Probes for independent Hi/Hi-Hi overfill protection that operates separately from the continuous gauge. See our Level Alarms.
Connect to Varec FuelsManager® to calculate real-time corrected volumes, manage alarms, and generate inventory and compliance reports across the tank farm. See FuelsManager®.