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Trim-to-size Paddle Type Switches for Flow/no Flow Detection

Trim-to-size Paddle Type Switches for ‘flow/no Flow’ Detection for Piping Systems 11/4" and Up


Item# FSW-21

Volume discounts available
Volume Discount Schedule
Quantity Price each
1-4 C$365.92
5-9 C$347.62
10-24 C$340.31
25-49 C$325.67
50-99 C$318.35
100+ C$311.03

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Lead Time (If not in stock): 7 Days
Trim-to-size Paddle Type Switches for ‘flow/no Flow’ Detection for Piping Systems 11/4" and Up FSW-21 FSW-21
  • Easy to Install
  • Switch Acts Bi-directionally
  • Minimum Flow Restriction
  • Less Than 3 psig Pressure Drop
  • Low Cost
  • Reed Relay for Long Life

FSW-21 Model Options

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*Highlighted options are not compatible. Please select a different combination.

Wetted Materials
Media Type
Flow Range
Max Operating Pressure
Max Process Temperature
Process Connection Type
Process Connection Size
Switch Rating and Type
Wire Length

FSW-20 series paddle-type switches easily install into pipes ranging in size from 1¼' on up using an ordinary pipe tee or threaded weld coupling. The paddle pivots to move out of the liquid’s path with increasing flow, thereby activating the switch. The paddle is easily cut for field installation for desired flow setting. Models FSW-21 and FSW-22 feature high pressure (2000 psig max.) and high temperature (to 150°C (300°F)) ratings for rugged installations.

   Housing: Brass, FSW-21; 316 SS: FSW-22
   Paddle: 302 SS
   Other Wetted: PTFE, ceramic
Body Length: 86 mm (3.4')
Paddle Length: 140 mm (5.5')
Paddle Width: 25 mm (1')
Operating Temperature: -34.4°C to 148.9°C (-30°F to 300°F)
Max Pressure: 2000 psig
Pressure Drop: 3 psig
Repeatability: ±5%
Set Point Accuracy: ±25%
NOTE: 22 mm (0.9') max. height boss from Pipe or Tee O.D. for full paddle swing
Switch: SPDT, 20 VA
Lead Wires: 18 AWG, 0.6 m (2') long, Polymeric
Max Viscosity: 200 SSU or 43 centistokes

Pipe Line Sizes
1-1/4' 1-1/2' 2' 2-1/2' 3' 4'
Approx Actuation/Deactuation Flow Rates (GPM water)
Act. De-Act Act. De-Act Act. De-Act Act. De-Act Act. De-Act Act. De-Act
1-1/4' 5 3 13 8 22 15 29 22        
1-1/2'     15 11 28 21 38 30        
2'         22 15 27 20 48 38    
2-1/2'             21 14 40 26 52 39
3'                 31 20 45 32
4'                     39 25
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Where is this part manufactured?

Asked by: jeffers
Thank you for your inquiry! The country of origin for this part is the US
Answered by: Application Engineer JM
Date published: 2021-08-31
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