This rugged inline FLS flow sensor offers superior performance. The fixed set point and simple design make it extremely dependable. The FLS is an ideal choice for applications requiring reliable flow detection. These In-line Piston style Flow sensors are made from wetted materials; ABS / PP. The wetted surfaces that are exposed to or in direct contact with the medium. Below is an abbreviated list of common chemicals used which have no effect on the flow sensor.


Acetate, Benzene, Carbon Dioxide, Ammonia, Acetone, Chlorine, Cider, Butyl, Isopropyl, and Barium Sulfate

The in-line flow sensor provides an accurate yet cost-effective solution for setpoint flow monitoring (flow or no flow) they feature a simple make or break signal using reed switch technology. The device can be mounted vertically or horizontally.

Principle of Operation

In a flow switch assembly, a magnet is placed within a piston that is loaded against a spring which compresses when water flow starts. The piston and spring are within the flow path of the liquid media.  Outside the flow path, a magnetic reed switch is located such that when the piston/magnet is properly positioned near the reed switch the contacts will close, indicating that the water is flowing above the sensor’s flow limit.


Flow Switches provide a binary output function to tell the user if the flow is greater or less than a pre-determined flow limit.  This Flow Limit means the minimum physical movement (velocity) of liquid in a pipe that causes a switch to actuate.  For flow rates less than the Flow Limit, including a complete stoppage, the switch to reverts to the original position.

A flow sensor can perform specific functions based on need. For example, flow switches are used as a backup control signal.  Some fluid delivery systems have many valves used to shut off, re-direct, or mix a number of fluids.  These critical valves, if they fail, can cause problems like leaks, under or overfilled vessels, or improper mixing levels, all of which can lead to very expensive mediation.  Flow switches are used to verify if the flow is present (or not) downstream of these valves and have proven to be an important backup sensor for critical flow management systems.


Tankless Water Heaters

Tankless water heaters are becoming a widely popular solution for water heating needs. The availability of hot water on demand and the perceived limitless supply of hot water make these types of water heaters much more attractive than traditional tank water heaters. These water heaters also provide long-term energy savings since energy is used only when there is a demand for hot water. In order to effectively heat the water when there is a demand, a sensor is needed to detect the flow of water. A flow sensor is used to detect the presence of water flow and turns on the system to heat the water. Whenever there is a hot water demand, a flow switch within the tankless water heater identifies the demand and initiates the heating process. This sensor monitors the presence of water flow while two other sensors measure the incoming and outgoing water temperature. This information is transmitted continually to a microprocessor controller which determines the precise amount of power to send to the heating elements to heat the water to the desired temperature.


  • Electronic Equipment: Laser Heads, Welders, Power Supplies, High-Speed Spindles, X-Ray Tubes, Semiconductor Equipment
  • Bearings or Gears: Presses, Rotating Equipment, Conveyors, Machine Tools, Robotics
  • Processing & Dispensing Equipment: Water Purifications and Filtering, X-Ray Film Processing, Beverage Dispensing, Chemical Additives, Gas Sampling, Distilling

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