ABSTRACT
Flow switches are used to determine if the flow rate is a certain value. This value (the setpoint) can be fixed or adjustable. When the setpoint is reached, the response can be the actuation of an electric or pneumatic circuit When the flow switch is actuated, it will stay in that condition until the flow rate moves back from the setpoint by some amount. The least expensive and therefore the most widely used are the various paddle type devices. At “no flow” the paddle hangs loosely in the pipe in which it is installed. The range and actuation point of paddle switches can be changed and adjusted by changing the length of the paddle. For any given pipe size, the actuation flow rate decreases as the paddle length increases.
