Paddle flow switches, micro-switch contact, 1/2” BSPP male thread


Main uses: Water flow detection on water pipes

Functional principle: Balanced paddle, perpendicular to the main flow, actuating a micro- switch. Flexible elastomeric gasket between paddle and electric switch

Weight N/A
Flow sensing

Main housing material

Paddle material

Mounting type


Electrical rating

Ingress protection

Maximum flow detection (L/min)

Minimum flow detection (L/min)

Nominal pressure at 20°C

Liquids temperature range (°C)

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Size and pressure Flow sensing:

Cleavable paddle


1/2” BSPP thread



Electrical rating Mounting position Type



Main uses: Water flow detection on water pipes

Functional principle: Balanced paddle, perpendicular to the main flow, actuating a micro- switch. Flexible elastomeric gasket between paddle and electric switch

Main housing material: PPO, fiber glass reinforced, usable with potable water.

Paddle material: Polypropylene, resistant to ozone and water disinfection products

Paddle gasket: Santoprene, resistant to ozone and water disinfection products

Electrical rating: 5A resistive, 230V AC

Electric contact type: SPDT, open or close by flow rise

Liquids compatibility: For use with clean water and liquids without chemical incompatibility with PPO and Santoprene

Nominal pressure at 20°C: 1MPa (PN10)


Assembly on pipes:



Average Flow detection values vs pipe I.D. and paddle length (Liters/min)


Paddle length

Pipe ID (mm)***

25 32 40 50 63
*Close **Open *Close **Open *Close **Open *Close **Open *Close **Open
1 34 32 67 63 123 113 225 200 506 424
1+2 23 19 50 48 98 93 173 153 389 324
1+2+3 40 38 76 73 143 128 321 271
1+2+3+4 61 58 110 106 220 200
1~5 49 46 89 84 200 178
1~6 73 68 165 150
1~7 62 58 152 138
1~8 133 123
1~9 113 108
* Close by flow rise (L/min) of contact open at no flow position

** Open by flow decrease (L/min) of contact open at no flow position. Average values for indication only. Standard tolerances ±30%

Nominal diameter: Can be used on 32 to 63 mm internal diameter pipes

The paddle is cleavable and can be cut at various lengths upon pipe diameter. There are cutting lines numbered 1 to 9 every 5mm.

Recommended mounting position: Vertical, with paddle downside. Other positions are possible with a change in the calibration value related to the paddle weight. .

Water pipe connection: Male thread 1/2”(BSPP) and NBR gasket. Must be used on a BSPP ½”female fitting perpendicular to the main pipe.

Recommended torque: 7Nm

Liquids temperature range: 5 to 80°C

Ambient temperature range: 5 to 50°C

Ingress protection: IP65

Electrical connection: 3 x 0.75 mm² cable, PVC insulation, style H05VVF.

Installation instructions:

  • Check carefully the paddle orientation: The arrow on housing must be exactly parallel to the pipe
  • A 5 mm minimum gap must be respected between end of the paddle and tube wall opposite to the 3/4”
  • We recommend the use of nozzles of length less than or equal to 18mm between the gasket seat and the inside of the tube and with an inner diameter greater than or equal to 20mm, to avoid blocking of the

Accessories: 1/2” female PVC saddles forDN40 to DN100 (OD) PVC pipes, and other fittings: see last section of this catalogue

Options: cable with connector or terminals, other cable length, paddle type B (see type R1B)


Main references





Technical informations associated to this product

  • Flow switches historical foreword

    In antiquity, the flow measurement was one of the first means of time measurement. But it was not until the steam engines development and the need to control their water supply, that measuring devices were developed.
  • Flow switches technical foreword

    A certain force is required to actuate the electrical contact device. It can range from a few tenths of grams for systems with reed contacts with a power rating of 10 to 20VA (0.5Amp), to 50 grams for snap action micro-switches with a 5Amp 250V rating
  • Electrical contacts

    As numerous mechanisms exist, we decided not to distinguish on the basis of constructive technique, but according to their operation speed, which is the key element.