A basic flow switch is a simple device used to detect the presence or absence of fluid flow (in this case, gas flow) within a pipe or duct. It operates based on the principle of differential pressure, utilizing a paddle or vane to sense the flow rate.
Here's how a basic flow switch detects gas flow in pipes:
Physical Configuration: The flow switch typically consists of a housing that is connected to the pipe or duct carrying the gas. Inside the housing, there is a movable paddle or vane mounted on a pivot.
Flow Direction: The flow switch is designed to be installed in a specific orientation to ensure proper functioning. It is essential to align the flow switch according to the direction of gas flow.
Differential Pressure: As the gas flows through the pipe or duct, it exerts pressure on the paddle or vane. The pressure on one side of the paddle is higher than on the other side, creating a differential pressure across the paddle.
Paddle Movement: The differential pressure causes the paddle or vane to move. When there is no flow or very low flow, the paddle remains in a neutral position.
Switch Mechanism: Inside the flow switch housing, there is a mechanical switch connected to the paddle. When the paddle moves due to the gas flow, it actuates the switch. The switch either opens or closes an electrical circuit, depending on the design of the flow switch.
Electrical Signal: The change in the switch state generates an electrical signal. For example, if the switch is normally open, gas flow will close the switch and complete the electrical circuit. If it's normally closed, gas flow will open the switch, breaking the circuit.
Flow Detection: The electrical signal generated by the flow switch can be used for various purposes, such as activating alarms, triggering other devices or equipment, or providing feedback to a control system.
Flow switches are widely used in various applications, including HVAC systems, industrial processes, gas supply lines, and more. They are relatively simple and cost-effective devices for detecting fluid flow in pipes and ensuring proper operation of systems that rely on the flow of gas or other fluids.