An Intech article, Temperature Measurement and Control Fundamentals, highlights the importance of temperature measurement.
Temperature is arguably the most extensively measured variable in process industries. If a temperature measurement is not accurate, repeatable, and reliable, it can have a detrimental effect on process efficiency, energy consumption, product quality, and process safety. Each temperature measurement system must be evaluated carefully and designed to satisfy process requirements.
Thermowells play an essential role in temperature measurements. The thermowells section on Emerson.com provides an overview.
Thermowells (1) are closed-end metal tubes installed pressure-tight into process vessels or piping, protecting temperature sensors (2) from harsh industrial process conditions, such as flow-induced stress, high pressure and corrosive chemicals. Additionally, thermowells allow the sensor to be easily removed from the process for calibration or replacement without requiring a process shutdown. Based on the stem profile, you can optimize your thermowells for response time or robustness. For the most accurate temperature measurement, size your thermowell to place the tip in the center of the pipe.
Connections with the process piping include welded, flanged, threaded, and Van Stone. The stem profiles can be stepped, tapered, straight, and twisted. The thermowell page highlights the strengths of both connection types and stem profiles.
The American Society of Mechanical Engineers (ASME) PTC 19.3 TW – Thermowells provides 4 quantitative criteria for efficient and safe design: Frequency, Dynamic Stress, Steady State Stress, and Hydrostatic Pressure Limits.
To aid in meeting this engineering standard, the Rosemount Thermowell Design Accelerator complies with PTC 19.3 TW.
Other calculation tools to assist in your engineering efforts include the Temperature Engineer’s Guide and the Temperature Model Code Converter, which converts legacy model numbers to the Rosemount 114C thermowell and 214C temperature sensor.
Visit the Temperature Measurement section on Emerson.com to learn more about the technologies and solutions to improve the performance of your process operations.
