SMN - Flow Switch for Liquids

Brand: KOBOLD Instruments, Inc

KOBOLD SMN variable area flow switches are used when extremely low flow switching points are required in combination with minimum pressure loss at high flow rates. 

The liquid flow switch, with all-metal wetted parts, works on the float principle. However, it does not use the standard conical metering tube or slotted measuring nozzle. Instead, a float with an integral magnet is suspended within a cylindrical measuring tube. 

The float is moved by the flow stream against the magnetic field of an opposing magnet mounted in the top of the instrument. 

The magnetic field produced by the float activates a reed contact at the switch point. The reed contact is mounted on the outside of the SMN liquid flow switch body. 

The special construction of the switch’s float and flow tube means that only a low flow is required to raise the float and thus close the contact. 

When the float reaches the top of its travel, an additional flow path opens, allowing high flow rates without a significant increase in pressure loss. 

When the flow is interrupted, the float is moved back down the flow tube by the opposing magnetic field and the contact opens.
  • Low Switch Point
  • Low Pressure Drop at High Flows
  • Brass or SS Construction
  • N/O or SPDT Reed Switch
  • Certifications/Approvals: cCSAus
  • Made in the USA
  • Quick Delivery


Switching Range

  • 0.4 to 13 GPM

Switch Point

  • 0.25 to 1 GPM Falling


  • 1” NPT Thread

Body Material

  • Ni-plated Brass
  • Stainless Steel

Maximum Pressure

  • Brass: 3600 psig
  • Stainless Steel: 5000 psig

Maximum Temperature

  • 212° F


  • N/O or SPDT Reed Contact

Media Category

  • Liquid


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