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MCG 351

Average Temperature Probe

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MCG 351

Terminal operations managers, custody transfer officers, process engineers, and EPC specifiers require accurate averaged temperature data to support corrected volumes, inventory reporting, and regulatory compliance.

The MCG 351 Average Temperature Probe delivers this with ±0.25 °C accuracy using 1 to 16 platinum RTD elements spaced along the probe length. Unlike single-point sensors that can create measurement errors in stratified tanks, the MCG 351 automatically identifies which RTD elements are submerged and computes a true averaged temperature, aligned with API MPMS requirements for legally defensible custody transfer.

Built for harsh storage environments, the probe features:

  • A flexible 316 stainless steel armored hose
  • Hermetically sealed conductors for long-term corrosion resistance
  • An anchor weight to maintain vertical stability in tall tanks

The probe supports both standard and high-temperature applications, from chilled chemicals to hot asphalt.

When paired with the MCG 2350 Average Temperature Converter, the probe becomes intrinsically safe and integrates seamlessly with L&J and Cognesense tank gauging systems.

The result is a reliable solution engineered for accuracy, compliance, and long-term durability across a wide range of tank types and operating environments.

MCG 351
MCG 351 Average Temperature Probe
MCG 351

Features

True Averaged Measurement

Multiple platinum RTD elements capture vertical temperature variations, eliminating bias from stratification and ensuring accurate corrected volumes for custody transfer.

API-Compliant Design

Meets global API MPMS averaging requirements, reducing temperature-driven custody disputes and improving confidence in official inventory calculations.

Wide Temperature Capability

Supports both standard and high-temperature ranges, enabling use with chilled chemicals, refined products, and high-temperature asphalts.

Intrinsic Safety Option

Achieves hazardous-area compliance when paired with the MCG 2350 converter, providing safe temperature measurement in classified environments.

Robust Mechanical Durability

316 stainless-steel hose, hermetically sealed conductors, and anchor-weighted construction withstand corrosive fluids and ensure long-term stability.

Seamless System Integration

Connects directly to L&J gauges and transmitters, enabling automated temperature selection, digital averaging, and standardized communication.

Applications

  • Custody Transfer Measurement: Provides averaged temperature data essential for accurate corrected volumes, protecting against disputes and ensuring audit-ready compliance.
  • Refined Product Terminals: Resolves temperature layering in multi-grade products to keep billing accurate and maintain trust between suppliers and customers.
  • Crude Oil Storage: Detects stratification that leads to significant volumetric errors, ensuring fair measurement in large, vertically layered crude tanks.
  • Chemical Storage Tanks: Supports accurate density and quality calculations in sensitive chemical processes where temperature precision affects product specification.
  • High-Temperature Service: Suitable for hot products such as asphalt or heavy oils, maintaining probe integrity and accuracy under demanding temperature conditions.
  • Tall Vertical Tanks: Multi-element configurations up to 82 ft ensure reliable averaging for deep tanks where single-point readings are insufficient.
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Specifications

Accuracy

±0.45 °F (±0.25 °C)

Standard Temperature Range

–58 °F (–50 °C) to +215 °F (+102 °C)

High-Temperature Option

–58 °F (–50 °C) to +400 °F (+204 °C)

Construction

316 stainless steel flexible hose, hermetically sealed leads

Standard Connections

3/4″ NPS or 1″ NPS (other NPS/NPT/flanged options available)

Pressure Rating

Hose assembly tested to 171 psig

Insulation Test

600 V RMS, resistors to housing

Elements

1–16 platinum RTD elements depending on tank height (2 ft to 82 ft)

Safety

Intrinsically safe when used with MCG 2350 converter

Mounting

Anchor weight standard for vertical stability

Approvals

UL, C-UL, ATEX, CE (with MCG 2350)

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If you have questions not covered here, please contact the Cognesense support team for assistance.

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Why is it important to measure average temperature instead of a single-point temperature?

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Liquids in large tanks often have temperature stratification, meaning the temperature varies at different levels. A single-point measurement can be misleading and lead to significant errors (up to ±0.5%) in volume correction and inventory calculations. The MCG 351’s multiple elements provide a true average, which is required by global standards for accurate custody transfer and compliance.

Is the MCG 351 compatible with other tank gauging systems?

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The MCG 351 is designed to work seamlessly with L&J’s gauges and transmitters. It is typically paired with the MCG 2350 Average Temperature Converter, which takes the multi-element input and provides a digital output that can be integrated with various host systems.

How is the MCG 351 protected for hazardous-area use?

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The MCG 351 is built with an intrinsically safe design, meaning it operates at a low-energy level that is insufficient to ignite a flammable atmosphere. When connected to the MCG 2350 converter, which contains a critical intrinsic safety barrier, the probe meets global approvals like UL, C-UL, ATEX, and CE for safe use in hazardous environments.

How does the probe determine which temperature elements to include in the average?

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The connected transmitter automatically identifies submerged RTD elements and averages only those values, producing an accurate, real-time average temperature.

What types of tanks can the MCG 351 be used in?

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It is suitable for crude oil tanks, refined product terminals, large chemical tanks, floating-roof tanks, cone-roof tanks, and high-temperature asphalt tanks.

Is the probe durable enough for corrosive or heavy products?

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Yes. The stainless-steel hose and hermetically sealed wires withstand corrosive fluids, heavy oils, and challenging tank atmospheres.

What is the maximum probe length available?

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Up to 82 ft in standard configurations, with lengths matched to tank height. Longer custom lengths are available upon request.

Summary

The MCG 351 Average Temperature Probe captures true vertical temperature profiles using multiple platinum RTD elements along a single probe, delivering ±0.45 °F accuracy for custody-grade volume correction. Designed for petroleum terminals and chemical storage, the MCG 351 pairs with Cognesense’s temperature converters and level gauges to eliminate stratification bias and ensure accurate inventory accounting.

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