SMN - Flow Switch for Liquids


  • Low Switch Point
  • Low Pressure Drop at High Flows
  • Adjustable Reed Contact
  • Brass or SS Construction
  • Maximum Pressure: 5000 PSIG
  • Maximum Temperature: 250°F
  • 1” NPT Process Connection
  • Settable trip point from 0.4 to 13GPM


SMN flow switches are used when extremely low flow switching points are required in combination with minimum pressure loss at high flow rates. Typical applications include the control of water and cooling circuits, high pressure cleaning devices, control of contaminated media in effluent and heating systems and a wide variety of other flow control systems.

The SMN, 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 body.

The special construction of the SMN 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.



Switching Range:on: 0.4-13 GPM H2O off: 0.25-1 GPM H2O
Housing Material: Brass or SS
Max. Temperature: 250°F
Maximum Pressure: Brass: 3600 PSIG SS: 5000 PSIG
Fittings: 1" NPT
Contact: N/O or SPDT
Maximum Contact Ratings: N/O: 240 VAC, 100 VA, 1.5 A / SPDT: 240 VAC, 60 VA, 1 A
Protection: NEMA 4
Approvals: UL, CSA



SMN - Flow Switch for Liquids



SMN - Flow Switch for Liquids