Paddle flow switches, reed switch contact, 1/2” male thread, long paddle


Main uses: The most simple flow switch with magnetic pull-back. Recommended mounting position is on horizontal pipes, but can be mounted in any position. For water flow detection on dia. 25 to 63 mm water pipes.


Weight N/A
Flow sensing

Main housing material

Paddle material

Mounting position


Electrical rating

Ingress protection

Maximum flow detection (L/min)

Minimum flow detection (L/min)

Nominal pressure at 20°C


Size and pressure Flow sensing:

Cleavable magnetic pull
back paddle


1/2” BSPP thread


Reed switch, close on
flow rise

Electrical rating Mounting position Type





R1S (1/2″ BSPP)

1: Paddle

2: Body

3: Cable


R1F (1/2″ NPT)

1: Paddle

2: Body

3: Cable

Main uses: The most simple flow switch with magnetic pull-back. Recommended mounting position is on horizontal pipes, but can be mounted in any position. For water flow detection on dia. 25 to 63 mm water pipes.

Functional principle:

Balanced magnetic paddle mounted perpendicular to the flow and activating a reed switch through the wall. The return of the paddle is by made by magnetic action, without spring. No seal or liquid can pass between the piping system and the electrical contact. Suitable for corrosive water pools and spas and salination chlo- rination and bromination systems. Must not to be used for water containing magnetic particles or high viscosity liquids, which block the movement of the paddle. Adjustment: Can be adjusted by cleaving the paddle

Main housing material: Polypropylene, resistant to ozone and water disinfection products, usable with potable water.

Paddle: Polypropylene, 13 mm width

Paddle shaft: Titanium, providing an outstanding corrosion resistance, and improved mechanical live

Electrical rating: Max 1A, Max 70W, Max 250V, resistive load. Use on inductive circuits reduces electrical rating. We recommend to protect the reed switch with contact protection device when used in inductive loads

Electric contact type: Normally open, closes by flow rise

Liquids compatibility: For use with clean water and liquids without magnetic particles and without chemical incompatibility with  polypropylene and titanium

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)


Not suitable for R1S

32 40 50 63
*Close **Open *Close **Open *Close **Open *Close **Open *Close **Open
1 26 6 38 15 79 30 127 58 172 108
1+2 28 11 63 18 83 37 143 73
1+2+3 20 7 49 10 63 27 105 53
1+2+3+4 19 7 57 22 93 47
1~5 48 15 72 31
1~6 48 9 66 23
* 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 25 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 6 every 5mm.

Recommended mounting position: On horizontal pipes. Mounting in other positions slightly modify the calibration

Water pipe connection: On female ½” fitting. On the type with BSPP thread, a NBR gasket is supplied with the product. On the type with NPT thread, thread sealant must be used.

Recommended torque: 7 Nm

Liquids temperature range: 5 to 80°C

Ambient temperature range: 5 to 50°C

Ingress protection: IP65

Electrical connection: 2 x AWG24 (0.2mm²) cable, PVC insulation, T80°, style UL2464.

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
  • 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 20 mm, to avoid blocking of the

Accessories: 1/2” PVC saddles for DN40 to DN100 (OD) PVC pipes, and other fittings: see last section of this catalogue

Options: cable with connector or terminals, other cable length

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.