In order to safeguard the temperature
sensors mounted in industrial procedures, thermowells
are widely used in factories or manufacturing units. A process stream where a
temperature sensor is required has a one closed-ended tube mounted in it. From the open end of the tube, the sensors
like thermocouple, thermometer or temperature detector are inserted, which
usually remains in the open air in the absence of the thermowell. Hence in
simple terms, we can say that a thermowell protects the temperature detectors
from the outside air so that the instrument can detect the exact temperature of
the fluid flowing in the process stream.
Let’s have a look at the functioning of the
thermowells.
How
does it work?
As thermowell is mounted in the process
stream, it comes in direct contact of the heat transferred from the fluid in
the stream. The heat flows inside the pipe containing the temperature sensor.
The heat gets accumulated in the pipe and allows the sensor to detect the
temperature at the highest point. As the senor is not in direct contact of the
outside air, it takes enough time to detect the temperature and displays the
exact value.
Replacement of a failed sensor is also an
easy ask even if it is enclosed in a thermowell because there is no need of
draining the pipe during the process. However, for the proper functioning of
the sensor and to measure the average temperature of the fluid, the diameter of
the thermowell should be slightly extended from the internal diameter of the
process tube.
Using a flanged connector or a welded tube
fitting, a thermowell is carefully mounted into the process pipe.
Construction
and material of thermowell
A metal bar is typically used to construct
an effective thermowell. This tube construction is able to protect the
temperature detector high process pressure, effects of fluid chemicals and
forces induced by the flow. In order to enhance the response speed, the
thermowell end is constructed at fewer diameters.
Teflon coated stainless steel metal is also
widely used to make thermowells to
avoid corrosion from the fluids. While there is small pressure differential and
high temperature, along with thermocouple element, a protective tube is used.
This protective tube is usually constructed with ceramic and alumina to avoid
chemical effect of thermocouple element. For extra protection, this tube is
inserted within a heavy protected tube made of silicon carbide.
How
to get the best installation?
As there are many online dealers available
for thermowells, you can choose any
one of them to get them installed for your manufacturing unit. However,
selection of the best dealer or installer is not an easy task as this is a
highly commercial and technical process, which requires great expertise. It is
advisable to choose the installer that completely understands your requirement
and has the best thermowell constructed with sturdy material.
You can even ask the installer to make a
prior visit to your factory for inspection of your process stream. This would
make it easy for both the parties to comprehend the exact requirement of the
process.
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