Magnetostrictive Level Gauge

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High-Precision Level, Interface, and Temperature Measurement

Magnetostrictive level gauges combine the simplicity of a float with the precision of time-based measurement, delivering some of the highest accuracy available for liquid and interface level monitoring. A sealed probe is inserted vertically into the tank, and one or two magnetic floats ride on the liquid surface. When the transmitter sends a brief current pulse down the probe’s internal waveguide, it interacts with the float’s magnetic field and creates a torsional pulse that travels back to the electronics. By timing this pulse with microsecond-level resolution, the system determines exact float position, producing continuous level readings with typical accuracy of ±0.001 inches.
Because the measurement is based on time-of-flight rather than calibration drift, magnetostrictive gauges provide long-term stability, excellent repeatability, and inherently precise interface measurement. They are unaffected by changes in dielectric or density and can simultaneously report total level, interface level (with a second float), and temperature when equipped with integrated RTDs. Installation is straightforward: the stainless-steel probe is mounted vertically through a riser or stilling well, and the float moves freely along the guide tube. Proper clearances, vertical alignment, and float selection ensure reliable operation even in challenging process conditions.
Cognesense magnetostrictive systems—built around the MCG 1010M transmitter and paired with rigid, flexible, or bottom-mounted probes such as the MCG 8150B or MCG 8151, are engineered for high accuracy, robust construction, and demanding industrial environments. With hazardous area approvals, multiple communication options, and compatibility with both single- and dual-float configurations, they deliver precise tank-level and interface data for fuel terminals, chemical storage, separators, and specialty inventory applications. This makes Cognesense the preferred choice when accuracy, reliability, and long-term stability are critical to plant operations.

When to Use a Magnetostrictive Level Gauge

Use an L&J magnetostrictive level gauge when you need high-accuracy, continuous level and interface measurement for tanks and vessels where safety, repeatability, and long-term stability matter most.
L&J’s magnetostrictive systems provide millimeter-level precision (±0.001 in.) and temperature profiling, making them ideal for custody transfer, inventory management, and process control across above- and below-ground assets.
These systems are especially effective for:
  • Underground storage tanks (USTs) at terminals, refineries, and fueling stations, where precise product and water-interface monitoring prevent leaks, overfills, and compliance issues.
  • Pressurized spheres and bullets for LPG, ammonia, butane, or propylene, where a sealed probe design handles high pressure and hazardous areas safely.
  • Refined product, crude oil, and chemical service requiring continuous level and interface data under vapor or temperature variations.
  • Hazardous or classified areas, with FM, ATEX, and IECEx approvals, plus digital communication

How Magnetostrictive Technology Works

Each probe contains a magnetostrictive wire and float assembly.
A low-voltage pulse travels down the wire; the float’s magnetic field disturbs it, creating a torsional “ping” that returns to the electronics.
By measuring the time-of-flight between pulse and echo, the system determines exact float position, unaffected by changes in pressure, vapor, or dielectric constant.

The result: absolute, repeatable level measurement with no recalibration drift.

MCG 8150B

MCG 8150B — Rigid Magnetostrictive Probe

Choose the MCG 8150B when you need precise product and interface measurement, BS&W detection, and average temperature data in rigid-mounted tanks—paired with the 1010M for high-resolution magnetostrictive accuracy.

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MCG 8151 — Flexible Magnetostrictive Probe

Choose the MCG 8151 when tall or underground tanks require flexible installation with accurate product/interface levels, BS&W, and temperature profiling—used with the 1010M for continuous high-resolution measurement.

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MCG 1010M

MCG 1010M — Magnetostrictive Receiver

Use the MCG 1010M whenever an 8150B or 8151 probe is installed, delivering continuous high-resolution level, interface, BS&W, and temperature data for critical specialty applications.

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Applications and Use Cases

Technology How It Complements Servo Gauges
Underground Storage Tanks (USTs)
Provides product and water-interface detection with sub-millimeter accuracy for regulatory compliance and leak prevention.
Pressurized Spheres & Bullets
Handles high-pressure hydrocarbons safely; float designs resist thermal expansion and vapor pressure effects.
Refineries & Petrochemical Terminals
Ensures custody-transfer precision with integrated temperature profiling and API 2350 overfill protection.
Chemical Process Vessels
Immune to dielectric or vapor changes; suited for corrosive or viscous media using stainless-steel or coated probes.
Water & Wastewater Systems
Monitors level and interface in sumps, clarifiers, and separators.
Renewable Fuels & Biogas
Detects oil/water or phase separation in digesters and storage tanks.
Food, Beverage, and Pharma
Cleanable, sanitary options with minimal maintenance.

Complementary Products From L&J Technologies

Global custody-transfer standards such as OIML R85, API MPMS and ISO 4266 emphasize continuous verification, traceability, and control of total measurement uncertainty. API MPMS and OIML methodologies for calculating corrected volumes are also built on the principle of cross-checking level, reference height, and tank calibration data. To meet these expectations in real-world tank environments, most operators rely on dual, independent level measurements to validate accuracy and detect drift before it impacts fiscal volumes.

While a single level gauge provides the primary reading, a complementary technology (such as servo + radar or radar + mechanical) creates the independent reference point these standards assume for maintaining certified accuracy classes and proving metrological integrity over time.

In practice, the accuracy and verification framework defined by OIML, ISO 4266, and API MPMS is best satisfied by a redundant level-measurement architecture—one instrument serving as the primary custody device, and a second providing the independent confirmation needed for auditability, traceability, and long-term measurement confidence.

See Our Guide To Level Measurement Techniques
Complementary Technology Where It Shines How They Complement Magnetostrictive Gauges
Servo Gauges (e.g., MCG 1500 SFI)
Custody transfer, density, and hybrid measurement applications requiring metrological accuracy.
Servo gauges enhance magnetostrictive systems by providing a secondary, independent reference for custody transfer and real-time density measurement, enabling redundancy and traceability in regulatory or fiscal operations.
Radar Gauges (e.g., EVO 1610 / EVO 2600 / MCG 1600SFI)
Non-contact, high-accuracy measurement in vapor, foam, or high-temperature conditions.
Radar provides non-contact verification of product level and performance under varying vapor or temperature conditions—ideal for cross-validation and redundancy in critical tanks or custody applications.
Float & Tape / Gauge Boards (e.g., Varec 2920+2500, MCG 2000 + 92021)
Mechanical simplicity, visual indication, and reliability without power.
Float & Tape systems act as a mechanical backup for magnetostrictive probes, ensuring API 2350 compliance and operator visibility during power or signal loss conditions.
Capacitance Level Probes (Cap Analog)
Interface detection, confined spaces, or smaller process vessels.
Compact capacitance or secondary magnetostrictive probes can be used for local interface or water-bottom detection—providing additional process insight where main tank probes are impractical.
Ultrasonic / Microwave / Capacitance Switches (e.g., Sonac, Microwave, Captrol)
Point-level safety interlocks and overfill prevention.
Switches establish independent alarm layers and fail-safe protection as required by API 2350, offering discrete high/low-level trip points to supplement continuous magnetostrictive measurement.

Summary

L&J Technologies offers the broadest portfolio of complementary level measurement solutions in the industry. By combining magnetostrictive probes with servo, radar, mechanical, and switch-based devices, operators can achieve:
  • Redundant, layered level protection that meets API 2350, MPMS, and ISO 4266 recommendations
  • Cross-verification between contact and non-contact methods for custody transfer applications minimizing losses
  • Continuous and point-level assurance across all tank types
Only L&J Technologies delivers this end-to-end measurement ecosystem, where each technology enhances the others for maximum reliability, safety, and accuracy across every storage and process application.