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Brass flow switch with paddle, 1-1/4 inch NPT threads, SPDT contacts

ITT McDonnell Miller

ITT McDonnell Miller FS7-4W Snap Flow Switch 1-1/4" MNPT 7.7 gpm 120/240VAC

SKU CH-HFDZ-RXQAD

Monitors liquid flow in 1¼-inch NPT piping and actuates an SPDT switch at 7.7 gpm for 120/240 VAC circuits

  • Product typeIndustrial/Heavy-duty Switch
  • Reliable flow detection with 7.7 gpm paddle switch
  • Handles extreme temps from -65 °F to 300 °F
  • 1-1/4" NPT connection fits standard piping
  • SPDT contacts rated 3.7 A at 240 VAC full load
  • Class I Div 1/2 and Class II Div 1/2 hazardous-location approved

Flow switch for 1-1/4" pipe systems

The FS7-4W snap flow switch monitors liquid movement in 1-1/4 inch NPT piping. It serves industrial and heavy-duty installations where automatic flow verification is required. The paddle mechanism activates at a fixed 4.8 gpm threshold. This unit is built for new deployments in hazardous-location environments.

SPDT contacts rated for 120/240 VAC circuits

The switch provides a single-pole double-throw contact set rated at 7.4 A full-load and 44.4 A locked-rotor at 120 VAC, or 3.7 A full-load and 22.2 A locked-rotor at 240 VAC. These ratings allow direct control of motor starters, alarms or relays without an intermediate contactor. No additional accessories or software are bundled with the device.

Class I and Class II hazardous-location approval

The housing carries Class I Division 1 and 2 Groups C and D plus Class II Division 1 and 2 Groups E, F and G ratings. This certification determines whether the switch can be installed in areas with flammable gases, vapours or combustible dusts. Ambient temperature limits span -65 °F to 300 °F.

How it compares

Measured against everything we stock in AV Accessories & Components, at today’s prices. Recalculated every night.

Price $605.99
Pricier than about 90% of the 3,838 comparable items (median $41.99).

Specifications

Product
Brand nameMcdonnell & Miller
Model nameFS7-4 W
Product typeIndustrial/Heavy-duty Switch

Questions about this item

How often should the paddle mechanism be inspected or replaced on the FS7-4W flow switch?

The paddle-type switch has no specified service interval; inspect it during routine system maintenance and replace if wear or corrosion affects the 4.8 gpm actuation point.

What electrical limit is reached first when the switch runs continuously at full load on a 240 VAC circuit?

The contact rating is 3.7 A at 240 VAC full load, so sustained current above that value will be the first electrical limit encountered.

How much heat does the FS7-4W generate when operating all day at its rated 7.7 gpm flow?

The switch body is rated for ambient temperatures up to 300 °F; internal heating from the 3.7 A full-load current at 240 VAC is minimal compared with that limit.

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