ITT McDonnell Miller
ITT McDonnell Miller FS251 1" MNPT SPDT Snap Flow Switch part
A brass paddle flow switch for 1-inch NPT pipe, rated 5.8 gpm at 32–227 °F with SPDT contacts up to 22.2 A at 240 V
- Reliable flow detection with 1" NPT paddle switch
- Operates in 32 to 227 °F ambient range
- Handles 22.2 A locked rotor at 240 V AC
- Brass housing resists corrosion in water systems
- Factory-new SPDT snap switch for general-purpose use
Application scope
The ITT McDonnell Miller FS251 is a brass paddle-type flow switch with a 1 inch NPT connection. It suits hydronic and HVAC circuits where a single-pole double-throw contact must signal flow presence at a fixed 5.8 gpm set point. The SPDT switching handles both 120 V and 240 V control circuits with the listed locked-rotor and full-load ratings.
Limits
Systems that require an adjustable flow setting, a different pipe size, or a contact rating beyond 22.2 A locked-rotor at 240 V should select another device. Media temperatures above 227 °F or below 32 °F also fall outside the approved range.
Decisive spec
The paddle mechanism triggers at exactly 5.8 gpm in a 1 inch or 6 inch pipe, so that single flow rate determines whether the switch matches the design flow of the circuit.
Highlights
- Reliable flow detection with 1" NPT paddle switch
- Operates in 32 to 227 °F ambient range
- Handles 22.2 A locked rotor at 240 V AC
- Brass housing resists corrosion in water systems
- Factory-new SPDT snap switch for general-purpose use
Specifications
| Brand | MCDONNELL & MILLER |
|---|
Questions about this item
How can I verify the FS251 flow switch is operating correctly after installation?
Confirm the paddle moves freely when flow reaches 5.8 gpm and the SPDT contacts switch at the rated 3.7 A @ 240 V full-load or 7.4 A @ 120 V full-load.
What comes with the FS251 and what must I supply separately?
The switch body with 1 in NPT brass housing and paddle is included; pipe fittings, wiring, and mounting hardware are not supplied.
Which flow-rate version of the FS251 should I select for a 1 in pipe?
This model is fixed at 5.8 gpm minimum and maximum, so it suits 1 in and 6 in pipes where that exact actuation point is required.
Also in this aisle
People compared these
Same shelf, same checkout — eight coins and a 30-minute rate lock.
