Multi-Point Thermocouples

I. Core Parameters

Note: "t" in the table refers to the actual measured temperature value; maximum temperature limits for protective tube materials: Stainless Steel ≤800℃, Inconel 600 ≤1100℃, Ceramic ≤1600℃, Silicon Carbide ≤1800℃.

II. Product Features

Synchronous Multi-point Temperature Measurement for Efficient Temperature Distribution Acquisition: A single sensor integrates 2~12 measuring points, enabling simultaneous temperature monitoring at different positions of the same measured object. It eliminates the need for multiple single-point thermocouples, significantly improving the efficiency of temperature distribution data collection and reducing equipment installation and maintenance costs.

Flexible Types and Specifications for Diverse Scenarios: Supports multiple thermocouple types including K, J, and T. The number of measuring points, spacing, protective tube material, and installation method can all be customized to accurately match the temperature measurement needs of different equipment such as chemical reactors, boilers, and pipelines.

Reliable Measurement Accuracy with Authentic Data: Adopts high-quality thermocouple wires that meet Class I and Class II accuracy standards, ensuring stable thermoelectric potential and minimal performance degradation at high temperatures. Equipped with a dedicated insulation structure, it effectively avoids signal interference between measuring points and ensures accurate temperature data for each point.

Excellent Protection Performance for Harsh Working Conditions: The protective tube is made of corrosion-resistant and high-temperature-resistant materials. The junction box supports multiple protection grades such as waterproof and explosion-proof, enabling long-term stable operation in harsh industrial environments such as high temperature, corrosion, humidity, flammability, and explosion, with a long service life.

Easy Installation & Maintenance with Strong Compatibility: The compact integrated structure reduces installation space occupation. Multiple installation methods adapt to different equipment interfaces. The terminals in the junction box are clearly arranged, facilitating wiring and later maintenance, and can be seamlessly connected with various industrial instruments, PLCs, and DCS systems.

Fast Response Speed for Real-time Temperature Feedback: The optimized structure design of thermocouple wires and protective tubes shortens the heat conduction path. With a response time of ≤5s in flowing medium, it can quickly capture temperature fluctuations at each measuring point, providing real-time data support for process regulation.

III. Related Component Specifications

1. Core Temperature Measurement Components

Thermocouple Wire: Uses high-quality wires complying with GB/T 16706-1996 standard. Type K wires contain nickel-chromium and nickel-silicon components, featuring high purity and stable thermoelectric performance. The wire diameter is determined by the number of measuring points and total length, typically 0.3~1.0mm, ensuring sufficient mechanical strength and thermoelectric potential output.

Temperature Measuring Nodes: Manufactured by welding process, with firm and smooth welding points, free from false welding and missing welding defects, reducing the impact of contact resistance on measurement accuracy. Each node is independently insulated to avoid signal crosstalk and ensure the independence and accuracy of single-node temperature measurement.

2. Protection & Insulation Components

Protective Tube: 304/316L stainless steel is suitable for medium-low temperature corrosive scenarios; Inconel 600 is suitable for high-temperature oxidation environments; corundum and silicon carbide are suitable for ultra-high temperature scenarios. The inner wall of the tube is polished to reduce thermal resistance and improve thermal response speed.

Insulation Material: Uses high-purity alumina ceramic beads or magnesium oxide powder, which have excellent high-temperature resistance and insulation performance. It can effectively isolate thermocouple wires from the protective tube below 1300℃ to prevent short circuits. The insulation material is tightly filled to avoid the deviation of measuring point positions caused by the movement of thermocouple wires in the tube.

3. Connection & Installation Components

Junction Box: The shell is made of die-cast aluminum alloy or stainless steel, with high strength and impact resistance. The waterproof type has a built-in sealing ring, and the explosion-proof type adopts an explosion-proof structure to ensure safety in corresponding protection scenarios. A terminal block is equipped inside the box to facilitate the distinguishing connection of wires for each measuring point.

Installation Accessories: Threaded joints are made of high-quality carbon steel or stainless steel, with high thread precision and tight fit; flanges adopt butt-welded or socket-welded structures, with pressure ratings up to PN1.6~PN10MPa; welding accessories support direct welding with the equipment body to improve installation firmness.

Compensating Wire & Transmitter (Optional): The material of the compensating wire matches the thermocouple, reducing the impact of ambient temperature on signal transmission. The transmitter is integrated into the junction box, which can convert multi-channel thermoelectric potential signals into standard 4~20mA current signals, facilitating long-distance transmission and system integration.

IV. Application Scenarios

With the core advantage of synchronous multi-point temperature measurement, this product is widely used in industrial scenarios that require temperature distribution data, mainly including:

Petrochemical Industry: Axial and radial temperature distribution monitoring of large chemical reactors and synthesis towers; multi-point temperature control of catalytic cracking units and distillation towers, ensuring uniform and stable reaction processes and improving product quality.

Power Energy Industry: Multi-point temperature monitoring of water wall, superheater, and reheater tube walls in thermal power plant boilers; temperature distribution collection of key components of nuclear power equipment, ensuring safe operation of power generation equipment and avoiding local overheating damage.

Metallurgical & Iron and Steel Industry: Multi-point temperature monitoring of furnace walls and crystallizers in blast furnaces, converters, and continuous casters; temperature distribution detection of ladles and torpedo cars, providing accurate data for smelting process regulation and improving steel quality.

Building Materials & Ceramic Industry: Axial temperature distribution monitoring of kiln bodies in cement rotary kilns and ceramic roller kilns; multi-point temperature measurement of furnace walls and molten pools in glass melting furnaces, ensuring uniform temperature during roasting and melting processes and improving product qualification rate.

Pipeline & Vessel Industry: Temperature monitoring along long-distance transmission pipelines; layered temperature distribution collection of large storage tanks (crude oil, chemical raw materials), avoiding stratification or solidification of media caused by uneven temperature.

Scientific Research & Laboratory Scenarios: Material heat treatment experiments and heat transfer characteristic research in universities and research institutions; temperature distribution testing of large experimental equipment, providing efficient and accurate temperature measurement support for scientific research data collection.

V. Product Advantages

Integrated Design Reduces Comprehensive Costs: A single multi-point thermocouple replaces multiple single-point sensors, reducing equipment procurement costs; simplifies the installation process, lowering labor and installation accessory costs; later maintenance only targets a single sensor, reducing maintenance workload and costs.

Temperature Distribution Visualization Aids Process Optimization: Synchronous acquisition of multi-point temperature data can intuitively present the temperature distribution curve of the measured object, helping technicians identify problems such as local overheating and uneven temperature, providing data support for process parameter adjustment, and improving production efficiency and product quality.

Strong Adaptability Covers Various Working Conditions: From low temperature to ultra-high temperature (-200~1800℃), and from ordinary environments to explosion-proof and corrosive environments, it can meet requirements through material and structure customization, with a wide range of applicable industries and diverse application scenarios.

Stable and Reliable with Low Operation Risk: High-quality raw materials and mature manufacturing processes ensure long-term stable operation of the product; each measuring point works independently, and the failure of a single point does not affect the normal temperature measurement of other points, reducing production risks caused by temperature measurement failure.

Convenient System Integration and Efficient Data Processing: Supports connection with various industrial control systems, enabling centralized collection and processing of multi-channel temperature signals; equipped with dedicated software, it can realize temperature data storage, analysis, and curve drawing, improving data utilization efficiency.

VI. Frequently Asked Questions (FAQs)

1. Is the more measuring points of a multi-point thermocouple, the better? How to choose reasonably?

Answer: Not necessarily. The number of measuring points should be determined according to the volume of the measured object, the complexity of temperature distribution, and process requirements: 2~3 points are sufficient for small containers or scenarios with uniform temperature distribution; 4~8 points can be selected for scenarios with complex temperature distribution such as large reactors and long-distance pipelines; up to 12 points can be customized for special scientific research scenarios. Excessive measuring points will increase costs and installation difficulty, and may cause data redundancy.

2. Will signal interference occur between different measuring points? How to avoid it?

Answer: Interference may occur if insulation treatment is improper. The product avoids interference through three designs: first, the thermocouple wires of each measuring point are independently insulated and isolated by alumina ceramic beads; second, the protective tube is filled with insulation powder to further block signal transmission; third, the terminals in the junction box are arranged independently with clear labels to avoid wiring confusion. Ensuring good grounding during installation can further reduce external electromagnetic interference.

3. How to select the protective tube material according to working conditions?

Answer: Follow the principle of "temperature matching + medium adaptation": ① For medium-low temperature (≤800℃), weak corrosion or non-corrosion working conditions, select 304/316L stainless steel; ② For medium-high temperature (≤1100℃), oxidation or slight corrosion working conditions, select Inconel 600; ③ For high temperature (≤1600℃) and non-corrosion working conditions, select corundum; ④ For ultra-high temperature (≤1800℃) or strong abrasion working conditions, select silicon carbide. For strongly corrosive media containing chlorine, sulfur, etc., 316L or special alloy materials are preferred.

4. Do multi-point thermocouples need regular calibration? Is the calibration method different from that of single-point thermocouples?

Answer: Regular calibration is required. The recommended calibration cycle is 1 year, and it should be shortened to 6 months when used for a long time under high temperature (above 1000℃) or strong corrosion working conditions. The calibration method is basically the same as that of single-point thermocouples. Each measuring point needs to be calibrated independently. Equipment such as constant temperature baths and tube furnaces can be used to place each measuring point in a standard temperature environment in turn, and compare the deviation between its output thermoelectric potential and the standard value to ensure that each point meets the accuracy requirements.

5. What are the special precautions for the installation and use of explosion-proof multi-point thermocouples?

Answer: ① During installation, ensure the junction box cover is tightened and the sealing ring is intact to prevent flammable gas from entering; ② The lead wire must be connected with explosion-proof flexible pipes, and ordinary wires are strictly prohibited; ③ The grounding terminal must be reliably grounded, with a grounding resistance ≤4Ω; ④ It is forbidden to disassemble the junction box or adjust the wiring in explosive environments; ⑤ Regularly check the integrity of the explosion-proof surface, and if scratches or rust occur, handle them in time to ensure explosion-proof performance.

6. When one measuring point is damaged, is it necessary to replace the entire sensor?

Answer: It is not necessary to replace the entire sensor. The product adopts a modular design. If a single measuring point is damaged due to wire breakage or other problems, you can contact the manufacturer to provide the corresponding thermocouple wire component for the measuring point, and professional personnel can perform local replacement and calibration to restore use, which greatly reduces maintenance costs. However, if the protective tube is completely damaged or multiple measuring points are damaged at the same time, it is recommended to replace the entire sensor.

The application of multi-point thermocouples is suitable for the production site where there is a temperature gradient that is not significant, and multiple locations or multiple locations must be measured at the same time. Multi-point thermocouples are widely used in large fertilizer synthesis towers, storage tanks and other devices.

The sheath integral multi-point thermocouple assembles a number of independent micro-armored insulated thermocouples in an outer protection tube, and then beats the entire product outer protection pipe to the outer diameter required by the user through drawing and other processes. The outer diameter of the armored integral multi-point thermocouple is usually Ф6-Ф8mm, and it has become a domestic temperature sensor in the chemical (fertilizer industry, synthesis tower, reaction tank), metallurgy, petrochemical and gas industries instead of imported temperature sensors by virtue of its high technical difficulty, excellent production technology, reliable product quality and perfect after-sales service. When using armored monolithic multi-point thermocouples, the user needs to bring their own external protective tube, otherwise they can only measure atmospheric pressure and non-corrosive media. The overall multi-point thermocouple of the armor should not be bent significantly to prevent damage to the internal sheath.

 

 

Manual Welding

Automatic Welding

Insulation Testing

Laser Marking

Warehouse Managing

Thermocouple Assemble

Vacuum Leak Detection

Surface Polishing

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