What is a flanged thermowell?

Ashcroft® flanged thermowell isolates and protects a temperature instrument’s sensing element from pressurized, high velocity and corrosive media. They ensure longer life and accurate measurement while allowing the sensing instrument to be removed without without shutting down the process.

How do you size a thermowell?

One rule of thumb is to insert a thermowell anywhere from one-third to two-thirds of the way into the fluid stream. Other guidelines recommend that the insertion length be 10 times the thermowell tip diameter or a minimum of 2 inches (50mm) into the process.

What is U length in thermowell?

The standard length from the sealing face of the cap and the face of the temperature sensor end of the well is 1-3/4”. “U” is the insertion depth of the thermowell. This is how much of the thermowell will be inserted into the process, and is measured from the cap face to the tip of the well.

How do I choose a thermowell?

A most important factor in selecting thermowell material is to determine the corrosive conditions to which the well will be exposed. Recommended materials for various services are given in the Thermowell Material Guide. The high mirror polish given to all wells enhances its corrosion resistance capability.

What is the purpose of a thermowell?

Thermowells are used to guard temperature sensors such as thermocouples, thermistors and bimetal thermometers against damage from excessive pressure, material velocity and corrosion.

How deep should thermowell be?

According to the thumb rule, the Thermowell should be inserted into 1/3rd or 2/3rd depth of the fluid stream.

How many types of thermowell are there?

There are 3 broad categories: screwed, flanged, or weld-in, and can be designed to accept thermocouples, RTDs, temperature gauges or filled systems. Thermowells can be machined from solid barstock, or fabricated from pipe.

What is Wake frequency of thermowell?

A thermowell should have a wake frequency ratio of 0.8 or less. If a thermowell fails to meet the frequency, pressure, or stress requirements, changes to the dimensions or material may help. Possible alterations include: Increasing the support diameter. Increasing the tip diameter.

How are thermowells made?

Thermowells designed for high pressure applications are typically machined from bar stock to ensure integrity. Smaller thermowells for use in low pressure environments may be constructed from tubing with one end welded closed.

What do you call the distance from the point of connection for the thermowell to the tip of the thermowell?

The insertion length is the distance from the connection point of the thermowell to the tip. To achieve the greatest accuracy possible, the insertion length should be long enough to allow the entire temperature sensitive portion of the measurement device to extend into the medium being measured.

What is the difference between thermowell and thermocouple?

A thermocouple is a temperature measuring device that is exposed to a process in order to determine its temperature. A thermowell is a structure that surrounds the thermocouple (or RTD) probe and protects it from aspects of the process such as fluid flow rates or caustic or degrading materials.

What is velocity collar in thermowell?

A velocity collar is a metal ring machined into the shank of a thermowell and installed tightly in to the standoff of a pipe. 1.2 Why use velocity collars? The goal of a velocity collar is to reduce the effective unsupported length of a thermowell.