A basic flow switch detects gas flow in pipes using a simple mechanical principle. It is typically designed to activate or deactivate an electrical circuit when there is a certain amount of gas flow in the pipe. Here's how it works:
Construction: A flow switch consists of a housing that contains a flow-sensing element and an electrical switch mechanism. The flow-sensing element is a vane or paddle that can move freely inside the housing.
Installation: The flow switch is installed in the gas pipe, and the direction of gas flow is important for proper functioning. The gas flow needs to pass over the flow-sensing element.
Gas Flow: When there is gas flowing in the pipe, it will exert force on the flow-sensing element (vane or paddle), causing it to move. The magnitude of the movement depends on the gas flow rate.
Activation Threshold: The flow switch is designed with a specific activation threshold. Once the gas flow reaches or exceeds this threshold, the movement of the flow-sensing element is sufficient to actuate the switch mechanism.
Switch Mechanism: When the flow-sensing element moves past the activation threshold, it triggers the electrical switch mechanism inside the housing. This switch can be either Normally Open (NO) or Normally Closed (NC) depending on the application.
Electrical Circuit: The flow switch is connected to an electrical circuit, usually a control system or an alarm system. When the switch is triggered, it either opens or closes the electrical circuit, depending on its configuration (NO or NC).
Result: The activation of the electrical circuit can be used to signal the gas flow status to a control panel, indicating that gas flow is present or absent. It can also be used for safety purposes, like shutting off the gas supply in case of a significant decrease or increase in flow rate.
It's important to note that basic flow switches are simple and commonly used for industrial and commercial applications where the flow rate is relatively steady. For more precise and sophisticated gas flow measurement, other devices like mass flow meters or thermal flow meters might be employed.