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Flow Switches

FSW300 Series

Flow Switches | FSW300 Series

Flow Switches

USD345.53 FSW301

  • Adjustable Switch Point
  • Low Pressure Drop
  • Economical
  • Field Installation for ½ to 8" Pipes
  • Instant Response
  • High Repeatability
Variable Area Flow Meters & Switches - View related products


The FSW301 flow switch comprises a paddle system with a permanent magnet attached. Above that magnet is a reed contact, located outside the flow of fluid. A second magnet with opposing poles creates the force necessary to reset the switch back to the no flow position.

When the monitored flow pushes the paddle and changes the position of the magnet in relation to the reed contact it activates the contact. As soon as the flow is interrupted, the paddle moves back to its starting position, which returns the reed contact to the initial position. The force necessary to push the magnet back is provided by the two magnets repelling each other. Using magnetic force instead of the usual leaf spring means the switch is considerably more stable in the long term and much less sensitive to pressure peaks.

The reed contact used as a sensing element consists of two ferromagnetic contact blades located in a glass bulb filled with inert gas. This practically eliminates wear resulting from contact burning. This construction allows a useful life of up to 100,000,000 switching cycles.

Maximum Switching Current: 1 A
Maximum Switching Voltage: 230 Vac, 48 Vdc
Maximum Rating: 26 VA, 20 W
Set Point Tolerance: ±15%
Plug Connector: DIN 43650 form A/ISO 4400 cable socket with terminal screws, suitable for outer cable diameter 4.57 to 6.85 mm (0.18 to 0.27")
Dimensions (Excluding Paddle or Tee): 114 x 38 x 89 mm (4.5 x 1.5 x 3.5")

Maximum Pressure: 25.165 bar (365 psi)
Maximum Process Temp: 110°C (230°F)
Maximum Ambient Temp: 80°C (176°F)
Protection Class: IP65
Connection: ½-14 NPT
Materials of Construction:
Body: Brass
Paddle System: Polypropylene, Noryl®
Shaft: Stainless steel

FSW302, 303, 304
Maximum Pressure: 25 bar (362 psi)
Maximum Process Temperature: 110°C (230°F)
Maximum Ambient Temperature: 80°C (176°F)
Materials of Construction:
Body: Brass
Pipe Section: Brass
Paddle System: Brass

FSW305, 306, 307
Maximum Pressure: 10 bar (145 psi)
Maximum Process Temperature: 60°C (140°F)
Maximum Ambient Temperature: 60°C (140°F)
Materials of Construction:
Pipe Section: PVC
Body: Polypropylene, Noryl®
Paddle System: Polypropylene, Noryl®
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What Other People Bought: When you see this icon, click on it to expand a list of products that other people have bought when they purchased this model.

Part Number/Desc.
Insertion Style Switches
Availability: 2 weeks
Flow switch, insertion ½ male NPT, setpoint adjustable from 4.0 to 132 GPM
Brass Tee Switches
Availability: 6 weeks
Flow switch inline 1/2" brass tee, 0.9 to 1.1 GPM setpoint range
Availability: 4 weeks
Flow switch, inline 3/4" brass tee, 1.8 to 2.4 GPM setpoint range
Availability: 5 weeks
Flow switch inline 1" brass tee, 3.5 to 4.4 GPM setpoint range
PVC Tee Switches
Availability: 7 weeks
Flow switch, inline 1/2" PVC tee, 1.3 to 1.8 GPM setpoint range
Availability: 7 weeks
Flow switch, inline 3/4" PVC tee, 2.5 to 3.2 GPM setpoint range
Availability: 7 weeks
Flow switch, inline 1" PVC tee, 2.8 to 3.9 GPM setpoint range
Click to expand/minimize a list of what others bought with the70A-2
Availability: 1 week
Fast pulse tone audible alarm
All amounts shown in USD
Note: Comes complete with operator’s manual.

Ordering Example: (1) 70A-2 fast pulse tone audible alarm, USD54.18  plus (1) FSW301 insertion style flow switch with 1/2 NPT fitting, USD345.53, USD54.18 + 345.53 = USD399.71
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