What is thermowell U length?
What is Thermowell U Length?
The thermowell U length, which is also known as the immersion length, is the part of a thermowell that goes from the bottom of the process connection (threaded or flanged) to the tip that goes into the process fluid. It tells you how far the thermowell—and, by extension, the temperature sensor—goes into the medium being measured.
The U length usually goes from 70 mm (2.76 inches) to 5000 mm (196 inches), although it might vary based on the diameter of the process pipe, the kind of fluid, and the needs of the sensor. It is very important to choose the right U length so that the sensitive part of the thermometer bulb or sensor element is fully submerged in the process fluid. If the immersion is too brief, the readings can be wrong because heat can move through the process connection wrong.
The U length of the thermowell also affects how strong and resistant to vibration it is. A larger U length can make vibration-induced failures (Von Karman vortices) more likely in situations with high speeds or high temperatures. So, engineers need to find a balance between immersion depth, the thermowell’s resonance frequency, and the parameters of the process.
In short, the U length tells you how far the thermowell goes into the process so that it can get correct temperature readings, work safely, and protect the temperature instrument from process pressure, corrosion, and flow impacts.
The main point is:
U length is the distance from the bottom of the process connection to the tip of the thermowell.
The usual range is 70 mm to 5000 mm.
Getting the right size is important for accuracy, safety, and sensor life.