Thermal flow switches are sometimes called thermal dispersion flow switches. They are precise flow sensing devices. Since they do not have any moving parts, thermal flow switches are considered to be more reliable. Thermal flow switches are compact in size and can be used in a wide range of pipe sizes. They are made from stainless steel.
What do thermal flow switches do?
There are many applications within the industry where knowing the condition of a fluid is vital; no-flow or flow in a pipe. It is used to measure a variety of liquids. Thermal flow switches provide flow sensing in pipes.
In general, thermal flow switches detect positive flow to control the downstream process. They also ensure safe machinery operation by detecting coolant flow.
How do thermal flow switches operate?
A thermal dispersion flow switch has two different temperature sensors. The first sensor acts like the reference and takes the temperature of the liquid where the flow of dispersion switch probe is submerged. The second sensor is located near a heating element. As the flow moves, a temperature change will be noted amid both the sensors. When the flow rate of the liquid increases, a cooling effect occurs as it moves past the warm sensor. The higher the flow speed, the more cooling will occur. A drop in the temperature variance between the two sensors shows that he flow rate is above the user-adjustable setpoint. If the flow rate drops, less cooling occurs this consequently increases the temperature difference. The thermal conductivity of the fluid provides the variation in heat transfer.
What industries rely on thermal flow switches?
Thermal flow switches are used in gas and oil, waste and water, chemical, power, steel production, semiconductor manufacturing, mining, metals, food, and beverage industries. They are also frequently used in pharmaceuticals, textiles, paper and pulp as well.
What are some advantages of using thermal flow switches?
Thermal flow switches have the following benefits:
- Have fewer installation restrictions;
- Higher sensitivity;
- No wear and tear or moving parts, therefore more reliable;
- Probe length is adjustable to suit specific applications;
- Depending upon the type of thermal flow switch, multiple types of output signals can be obtained;
- Have a wide temperature operating range;
- Has low maintenance requirements;
An Example where thermal flow switch is used
A thermal dispersion flow switch is used in Marine situations. The flow switch is installed within the sea water cooling inlet of the diesel engine. The switch detects the positive flow of the cooling water which enables the engine to operate.