A basic flow switch is a simple device used to detect the flow of gas or liquid in pipes. It is commonly employed in various industrial applications and systems to monitor the flow of gases, liquids, or other fluids. The mechanism used in a flow switch to detect gas flow in pipes may vary, but here's a general overview of how it works:
Flow Sensing Element: At the core of a flow switch is a flow sensing element. This element is designed to respond to the movement of gas within the pipe. There are different types of sensing elements used in flow switches, including:
a. Paddle or Vane Type: In some flow switches, a paddle or vane is positioned inside the pipe. When the gas flows through the pipe, it exerts force on the paddle or vane, causing it to move. The movement of the paddle or vane is then detected by the switch, triggering the switching action.
b. Differential Pressure Sensor: In other flow switches, a differential pressure sensor is used. This sensor measures the pressure difference between two points in the pipe, typically before and after an obstruction in the flow path. When the gas flow changes, the pressure difference alters, and the sensor detects this change, causing the switch to activate.
c. Thermal Sensor: Some flow switches use a thermal sensing element. As gas flows through the pipe, it carries away heat from a heated element in the switch. The temperature change caused by the gas flow is measured by the thermal sensor, and if it reaches a certain threshold, the switch is triggered.
Switching Mechanism: The flow sensing element is connected to a switching mechanism within the flow switch. The switching mechanism is responsible for making or breaking an electrical circuit based on the input from the flow sensing element.
Adjustable Set Point: Flow switches often have an adjustable set point. This means the sensitivity of the flow switch can be adjusted to detect different flow rates. By adjusting the set point, the flow switch can be configured to activate the switch at a specific flow rate, allowing for flexibility in various applications.
Electrical Output: When the flow switch detects sufficient gas flow (based on the set point), it triggers the switching mechanism to change its state. This can result in closing or opening electrical contacts, signaling the presence or absence of gas flow. The output can be used to control other devices, such as pumps, valves, or alarms, depending on the application.
In summary, a basic flow switch detects gas flow in pipes by utilizing a flow sensing element that responds to the movement or pressure changes caused by the gas flow. The sensing element's output is connected to a switching mechanism that activates when the flow rate meets or exceeds the set point, leading to the desired electrical output for further control or monitoring purposes.