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Introduction to Limit Switches for Actuators

Series SW

Limit Switches signal the open or closed position of air actuated ball valves

signals the open or closed position of the ball valve


  • Signals open or closed; with optional Limit Stops is adjustable to any limited open position
  • Plastic construction eliminates atmospheric corrosion
  • Water and dust-tight housing
  • Light weight, dependable design
  • Manual override of ball valve

Series SW signals the open or closed valve position for computer verification or to actuate other equipment based on the valve position.

Body material is PVC, seals are BUNA-N, and the assembly fasteners are stainless steel and can be shielded from the atmosphere if necessary. Of course none of these materials in the Limit Switch are in contact with the process liquid.

signals the open or closed position of the ball valve

The Limit Switch has a camshaft and two single-pole double throw switches. A signal line is wired “through” the switch to the equipment or computer being signaled. A 1/2″ NPT conduit fitting seals the wiring connection. AC resistive load rating is 10 amps for each contact. DC loads are rated for 60W (5A at 12 VDC, 2.5A at 24 VDC).

The switches make contact when the valve is either open or closed. The open position of the True Blue ball valve is adjustable for throttling by using the optional Series LS Limit Stop. Series SW Limit Switch is also adjustable to accommodate the throttle open position.


The limit switch is simply mounted to the actuator by two screws. These screws are sealed inside the unit. The photo above left shows the Limit Switch mounted on an air by spring actuator. The illustration above right shows what the Limit Switch looks like on an air by air actuator.

components of the limit switch.


  1. Mounting screw
  2. Switch adjustment screw
  3. 1/2″ NPT conduit fitting
  4. Ball valve closed switch
  5. O-ring seal (Buna nitrile)
  6. Cam button
  7. Ball valve open switch (variable open)

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dimensions of the limit switch.