McDonnell & Miller 304400 Cover

The McDonnell & Miller 304400 is a genuine replacement flow switch cover (Model FS4-3COV) engineered specifically for Xylem FS4-3 liquid flow switches and the AF-1, AF-2, and AF-3 airflow switch series. In demanding commercial boiler and process piping environments, maintaining the integrity of the switch housing is critical for protecting the single pole, double throw (SPDT) snap switch and internal sensitivity adjustments from dust, moisture, and mechanical damage. This OEM component ensures a precise fit, maintaining the NEMA enclosure rating required for safe operation in HVACR applications.

When performing field maintenance on liquid flow switches, a secure cover is non-negotiable for protecting the sealed Monel bellows and electrical connections. A cracked or missing flow switch housing can lead to terminal corrosion or erratic signals in the safety loop. Since the McDonnell & Miller 304400 cover is designed for high-vibration environments, it includes the necessary slots for the standard two-screw mounting configuration, allowing for rapid access during annual inspections or setpoint adjustments without compromising the mechanical flow switch assembly.

• Universal Compatibility: Engineered to fit the entire FS4-3 series and AF-1 / AF-2 / AF-3 air flow switch models, reducing the need for multiple SKUs in your service van.
• Internal Component Protection: Shields the sensitivity adjusting screw and electrical knock-outs from environmental contaminants that cause premature failure.
• OEM Precision: Guaranteed 304400 replacement part dimensions ensure the cover seats correctly over the internal switch mechanism for a proper seal.
• Durable Construction: Built to withstand the high ambient temperatures and humidity levels typical of boiler room and mechanical plant environments.

Does this cover include the mounting screws?
Replacement covers are typically designed to utilize the existing cover screws on the switch body; however, the cover features the correct slotted openings for standard McDonnell & Miller fasteners.

Can I use the 304400 on an FS7-4 series switch?
No, this specific cover is designated for the FS4-3 and AF air flow series only. Always verify your specific switch model number before installation to ensure the housing aligns with the internal SPDT switch orientation.

Will this cover help with electrical safety?
Yes, the FS4-3COV provides the necessary physical barrier between the technician and the live electrical terminals, maintaining the HVAC equipment safety standards required by local codes.

Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.