| By :
Sarah Simmons
Flow switches are a very common electrical part used in many applications in many industries, but what exactly is a flow switch? Read on to learn what a flow switch is and the many important functions that it does. In many applications, it is necessary to be able to determine whether air or fluid is flowing in a duct, pipe, or other type of line and to respond accordingly to whether it is flowing or not. Sometimes called a flow sensor, a flow switch by definition is a mechanical switch that turns on and off in response to the flow or non-flow of air, water, gas or other liquids. In most flow switches, the flow is detected with a paddle which gets displaced due to the force of air or fluid moving past it. Flow switches have three different ways of sensing the flow or non-flow of air and liquids: direct flow sensing, indirect flow sensing and venturi meter sensing. Direct Flow Sensing The simplest installation of a flow switch in the flow stream allows for direct flow sensing. This will detect if liquid or gas is flowing through the switch (within the limits of the product's flow rate capacity and differential pressure sensitivity). Indirect Flow Sensing Installing a flow switch in a bypass line so that only a portion of the system's flow passes through it is called indirect flow sensing. By detecting any flow rate within the unit's pressure rating (when the required pressure differential is present), indirect flow sensing dramatically expands the range of possible applications for a flow switch. Venturi Meter Sensing Venturi meter sensing is based on the concept that different flow velocities create different amounts of suction. The meter consists of a pipe incorporating a constriction or "waist," and the suction (lower pressure) and velocity in the pipe just past the waist are both greater than the upstream area. Since the difference in pressure depends upon flow velocity, it must also depend upon the quantity of fluid passing through the pipe per unit of time. Therefore, the pressure differential provides a measure for the flow rate. Flow Switch Applications Flow switches have many different applications, the most basic of which is to send an electrical signal to control switching units. An example of flow switch's most simple function is it might be used to turn off a pump when the flow rate falls below a predetermined minimum between reservoirs. Flow switches also provide a great solution for activating equipment at flow turn-on, detecting flow in spray/sprinkler systems and monitoring coolant flow. In addition, a flow switch might be used to protect the electric heating element from a central heating system from being energized before the air flow from the blower is established or detect if a ventilation fan in a hazardous location fails and air flow has stopped. The best way to get acquainted with a flow switch is to try one out for yourself. Find the best flow switch products online now, and discover the benefits of flow switches today!
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