A basic flow switch is a simple device used to detect the presence or absence of fluid flow in pipes or conduits. It operates on the principle of mechanical activation, where the flow of fluid triggers a physical mechanism that signals the flow switch to change its state. The switch can be used to monitor various types of fluids, such as water, gases, or other liquids.
The basic components of a flow switch include:
Flow Sensing Element: The flow sensing element is the critical part of the flow switch that directly interacts with the fluid flow. It is typically a vane, paddle, or turbine located within the pipe. When the fluid flows through the pipe, it imparts force on the sensing element, causing it to move or rotate.
Actuator: The flow sensing element is connected to an actuator, which is responsible for converting the mechanical motion of the sensing element into an electrical or electronic signal. The actuator can be a magnet, reed switch, microswitch, or other similar devices.
Electrical Contacts: The flow switch contains electrical contacts that are either normally open (NO) or normally closed (NC). The state of these contacts determines the output signal of the flow switch.
Here's how the basic flow switch works:
No Flow: When there is no fluid flow or the flow is below the minimum required level, the flow sensing element remains stationary or in a predefined position. In this state, the electrical contacts maintain their default state (either open or closed, depending on the switch's configuration).
Fluid Flow: When fluid flow reaches a sufficient velocity or volume, it interacts with the flow sensing element. The force exerted by the flowing fluid causes the sensing element to move or rotate.
Activation: The movement or rotation of the sensing element triggers the actuator, which, in turn, changes the state of the electrical contacts. For example, if the contacts were normally open, they close when flow is detected, and vice versa for normally closed contacts.
Signaling: The change in the state of the electrical contacts generates an electrical signal that can be used to indicate the presence or absence of fluid flow. This signal can be integrated into control systems, alarms, or other monitoring devices.
Flow switches are commonly used in various applications, such as monitoring cooling water flow in industrial processes, detecting water flow in HVAC systems, or ensuring fluid flow in firefighting systems. They provide a cost-effective and reliable way to ensure proper fluid circulation and prevent damage caused by insufficient or excessive flow.