Flow switch classification
These switches can be classified as either air or liquid flow switches.
They are used to monitor the flow of liquids,air or steam in various industrial applications where they send signals to other devices such as pumps to either turn off or on depending on the situation at hand.
These switches come with wide range of technology which enables them to guarantee high quality performance,resistant to corrosion,flexible actuation settings and wide range of designs among others.
Air flow switches -
They provide one of the cheapest way to detect the loss or change in air velocity. They are preferred for applications which require high to low velocities.Both the loss and change in velocity can be as a result of a number factors which includes dirty or clogged filter,an overload of the fan’s motor,loose fan wheel or close fan or damper inlet.
Vane actuated Switch
In these switch,as air flow through the pipeline,the vane is forced to swing in the direction which the wind blows.
Disc actuated switch
In this case the fluid flowing through the valve pushes the disc up and down which as a result lowers and raises the magnetic sleeve respectively.
This in makes the magnet to actuate the switch.The principle is almost the same as that of the vane actuated switch.
Liquid Flow Switches
They are used for a wide range of applications which include electrically operated equipment such motors or signal lights.
They can be used to start or stop an electrical equipment.
They are mostly used for general purpose application.
They are also used to detect flow in many industrial application such an event there is a failure of flow in certain pipes it can raise an alarm.
There are a number of factors to consider while installing these types of switches in a pipeline.
To ensure that the switch operates as required,the arrow on the casing must always point towards the direction of flow.
The angle at which the switch should be mounted on the pipeline is also important.
A filter must also be installed up stream to prevent foreign particles from entering the pipe.
They must also be mounted in regions where there is little or no turbulence. That is they should be installed away from bends or elbows.
With advancement of technology,there those flow switches have incorporated thermal technology.In such flow switches,a no flow indication condition is indicated by high temperature condition while the presence of flow is indicated by low temperatures.
Flow switches with thermal dispersion technology
Flow monitoring is an essential part of any industrial processes.For this reason most industries have been doing all that it takes to adopt some of the most reliable and efficient ways to control these processes.
For instances,most flow switches in the market today tend to feature the thermal dispersion technology.
Thermal dispersion technology is presently being used to monitor the flow of gases and liquids in many pipelines.
This technology is based on the fact that the amount of heat carried away from the heated probe increases as the velocity of the fluid increases.
In these switches,the existence of a greater difference in temperature indicates no-flow condition.
This temperature differences decreases with an increase in the rate of flow.
The rate at which it dissipates heat is directly proportional to the rate of fluid flow.The signal obtained from the RTD is converted to an electrical signal by the electronic conditioning circuit.
Most of these devices are rugged and reliable as compared to the traditional switches.
They are also durable and other problem such as clogging are completely eliminated.
Switches which features this technology can monitor all types of fluid and have a fast response to change in the flow velocity.