MCG 351 — Average Temperature Probe

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Overview

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

Built for harsh storage environments, the probe uses a flexible 316 stainless-steel armored hose, hermetically sealed conductors, and an anchor weight to ensure vertical stability in tall tanks. It supports 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 globally trusted solution engineered for accuracy, compliance, and long-term reliability across the widest range of tank types.
MCG 351 — Average Temperature Probe

Features

Wide Temperature Range

True Average Temperature Measurement

Multiple RTD elements detect vertical temperature variations and calculate a precise average, eliminating stratification errors.

Global Certifications

API MPMS-Compliant Performance

Meets global custody-transfer averaging methods, ensuring audit-ready corrected volume calculations.

High Accuracy Across the Entire Probe

±0.25 °C (±0.45 °F) accuracy ensures consistent measurements under dynamic product conditions.

Integrated Temperature Sensing

Flexible Temperature Ranges

Standard service from –50 °C to +102 °C and extended high-temperature capability up to +204 °C.

Rugged Brushless Design

Rugged 316 Stainless-Steel Hose Design

Hermetically sealed lead wires and corrosion-resistant construction withstand aggressive product environments.

Intrinsic Safety Option

Safe for hazardous locations when paired with the MCG 2350 converter.

Seamless Integration

Works directly with Cognesense/L&J servo gauges, radar gauges, and transmitters for automated averaging and digital communication.

Details

Applications

The MCG 351 supports a wide range of custody and process applications where vertical temperature variation significantly impacts volume accuracy:

  • Custody Transfer Correction: Provides accurate averaged temperatures essential for converting observed volume to corrected volume, preventing custody disputes.
  • Refined Product Terminals: Corrects for temperature layering in gasoline, diesel, jet fuel, and additives to maintain billing accuracy.
  • Crude Oil Storage: Detects stratified layers common in large crude tanks, improving mass balance and audit compliance.
  • Chemical Storage Tanks: Supports temperature-sensitive density and quality calculations for regulated or specialty chemical processes.v
  • High-Temperature Applications: Handles hot asphalt, heavy fuel oils, and thermally demanding products with high-temperature probe options up to 204 °C.
  • Very Tall Vertical Tanks: Up to 16 RTD elements and probe lengths to 82 ft ensure accurate temperature data in deep storage tanks where single-point probes fall short.

Technical Specifications

Table Header Table Header
Accuracy
±0.45 °F (±0.25 °C)
Temperature Range
  • Standard: –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 lead wires for corrosion resistance and long-term stability
Pressure Rating
Hose assembly tested to 171 psig
Insulation Test
600 V RMS, resistors to housing
RTD Element Options
1–16 platinum RTD elements depending on tank height (2 ft to 82 ft)
Connections
  • Standard 3/4″ NPS or 1″ NPS
  • Additional NPS, NPT, and ANSI flanged connections available
Safety
Intrinsically safe when paired with the MCG 2350 converter
Mounting
Anchor weight included for vertical stability
Compatible Equipment
  • MCG 2350 Average Temperature Converter
  • Cognesense servo gauges, radar gauges, and tank gauging transmitters

Documents and Downloads

Product Flyer

Have a look at the flyer to get all the tech specs and product features. Brochure

User Manual

Read the manual for detailed information and instructions. Manual

Calibrations

Check out a sample cert from our calibration lab. Certificate

Contact Support

If you have a question that we have not covered then just get in touch and we’ll be happy to help.

Contact Us

FAQs

We have tried to answer the most common questions we are asked here.

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.

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.

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.
The connected transmitter automatically identifies submerged RTD elements and averages only those values, producing an accurate, real-time average temperature.
It is suitable for crude oil tanks, refined product terminals, large chemical tanks, floating-roof tanks, cone-roof tanks, and high-temperature asphalt tanks.
Yes. The stainless-steel hose and hermetically sealed wires withstand corrosive fluids, heavy oils, and challenging tank atmospheres.
Up to 82 ft in standard configurations, with lengths matched to tank height. Longer custom lengths are available upon request.