A basic flow switch is a simple device used to detect the presence or absence of fluid flow (including gas) in a pipe or conduit. It is commonly used in various applications, including gas pipelines, industrial processes, and heating, ventilation, and air conditioning (HVAC) systems. The flow switch typically operates on a mechanical principle and consists of a few essential components. Let's explore how it works:
Paddle or vane: The flow switch contains a paddle or vane that is designed to move or pivot in response to the fluid (gas) flow. The paddle is positioned within the pipe or conduit, and its orientation changes based on the direction and force of the flow.
Spring or counterbalance: The paddle is connected to a spring or counterbalance, which provides resistance against the flow. This resistance determines the minimum flow rate required to activate the switch.
Switch mechanism: The flow switch incorporates a switch mechanism, which is typically a microswitch or a reed switch. This switch has two states: open and closed. When the flow rate is below the minimum required, the switch remains in the open state, and no signal is sent. However, when the flow rate exceeds the threshold, the force of the flow overcomes the resistance of the spring or counterbalance, causing the paddle to move, and the switch changes to the closed state, completing an electrical circuit.
Electrical connections: The switch is connected to an electrical circuit that controls the gas flow system or activates an alarm or monitoring system. When the switch is closed due to sufficient flow, it allows current to pass through, triggering the connected system accordingly.
When there is no flow or the flow rate falls below the minimum required, the switch returns to the open state, breaking the electrical circuit. This indicates that there is no flow or inadequate flow, and appropriate actions can be taken based on the system's requirements, such as shutting off the gas supply or triggering a warning alarm.
It's important to note that the sensitivity and minimum flow rate required to activate the flow switch can often be adjusted or calibrated to suit the specific application and flow conditions. Additionally, flow switches come in different designs and configurations to accommodate various pipe sizes, flow rates, and fluid types.