Thermocouples: The Most Common Pyrometer on Ship
Thermocouple is a device which is widely used as a pyrometer on board ship for continuous measurement of temperature for various machineries like Main engine, Auxiliary engine, gas turbines etc.
It is absolutely important to choose the correct thermocouple material for different temperature range operation, depending upon the machinery and thermocouple location, where the parameter has to be measured.
Construction of Thermocouple
A thermocouple consists of two dissimilar homogeneous materials connected together. The materials used depend upon the application and usage. Normally, following materials are used for different temperature range:
Copper – constantan (copper nickel alloy) for range of -200 to 400 °C
Iron – constantan for temperature range of −40 to +750 °C
Chrome – alumel (alloy of nickel, manganese, aluminium and silicon) for temperature range of −200 to +1350 °C.
These materials are connected together in a ceramic sheath covered again by a metal sheath and fitted at desired locations like exhaust manifold etc. The one end of the thermocouple is placed in hot junction and other end is kept in a constant cold junction. These materials are led to a temperature indicator through amplifier and compensator lead. The amplifier and compensator lead (normally made up of copper and dose not effect the circuit) helps in transmitting the output to a remote location.
Principle & Working
Thermocouple works with the principle of “seebeck effect” which states that-“Temperature between two dissimilar metals in a circuit converts into electric current”
When two dissimilar metal wires joined, suppose iron and constantan, are coupled together and exposed to difference in temperature at both the ends, then emf is generated and current flows from hot to cold side.
The magnitude of the current depends on the temperature difference between the junctions.
If one junction is kept at constant temperature, then the value of temperature for the other junction can be easily determined.
Advantages of Thermocouple
- Can be used for remote temperature sensing.
- It can be used for continuous temperature sensing.
- Temperature difference can be measured with high accuracy.
- They are inexpensive and easily interchangeable.
You may also like to read-What is Oil Discharge Monitoring and Control System (ODMCS)
⚓️ Enhance Your Knowledge. Prevent Accidents. Stay Safe at Sea.
1. eBooks for Engine Department
Master machinery operations, troubleshooting, and safety procedures with expertly written guides tailored for marine engineers. Prevent costly breakdowns and onboard accidents through practical knowledge.
👉 Explore Engine Department eBooks
2. eBooks for Deck Department
Sharpen your seamanship, navigation, and cargo-handling skills with real-world case studies and practical insights designed for deck officers and cadets.
👉Discover Deck Department eBooks
3. eBooks on Electrical Fundamentals & Issues
Understand marine electrical systems, identify potential faults, and prevent onboard electrical failures with step-by-step explanations from industry experts.
4. Pocket Guides for Quick Reference
Compact, handy, and loaded with essential checklists—perfect for on-the-go reference during operations and emergencies at sea.
5. Combo Packs to Save Big
Access multiple expert eBooks at discounted prices. Ideal for professionals seeking complete safety and operational knowledge across various ship departments.
6. Digital Maritime Courses – Learn at Your Own Pace
Upgrade your competence with Marine Insight Academy’s online courses. Learn from industry professionals anytime, anywhere, and become a safer, smarter seafarer.
Disclaimer :
The information on this website is for general purposes only. While efforts are made to ensure accuracy, we make no warranties of any kind regarding completeness, reliability, or suitability. Any reliance you place on such information is at your own risk. We are not liable for any loss or damage arising from the use of this website.
Disclaimer :
The information on this website is for general purposes only. While efforts are made to ensure accuracy, we make no warranties of any kind regarding completeness, reliability, or suitability. Any reliance you place on such information is at your own risk. We are not liable for any loss or damage arising from the use of this website.
Related Articles
About Author
An ardent sailor and a techie, Anish Wankhede has voyaged on a number of ships as a marine engineer officer. He loves multitasking, networking, and troubleshooting. He is the one behind the unique creativity and aesthetics at Marine Insight.
Subscribe To Our Daily Newsletter
By subscribing, you agree to our Privacy Policy and may receive occasional deal communications; you can unsubscribe anytime.
Hi, extremely useful information about thermocouples. I would like to learn more about the likely faults someone can encounter in a thermocouple device,
Thank you and i will appreciate you comments below.
Regards