Honeywell FS4-3S Liquid Flow Switch

Description

Industrial fluid process monitoring requires resilient hardware, and the FS4-3S flow switch provides exceptional performance in challenging environments. This liquid flow sensor utilizes a paddle actuation mechanism to monitor fluid movement in closed piping systems. Featuring a high-durability stainless steel body and Monel bellows, the FS4-3S (Part Number 114641 / FS4-3S/U) is engineered to withstand corrosive process fluids where standard brass components would degrade.

The mechanical action of fluid flow against the paddle triggers a Single-Pole Double-Throw (SPDT) electrical switch. This simple yet highly reliable design allows operators to integrate the flow switch into automated control networks to cycle pumps, activate alarms, or signal downstream PLC or DCS platforms during critical flow fluctuations.

Features

• Corrosion-Resistant Construction: Built with a stainless steel body and Monel bellows to handle aggressive or brackish liquids safely.
• Flexible Switching: SPDT electrical contact structure supports both normally open and normally closed wiring profiles.
• Mechanical Actuation: Responds accurately to fluid velocity variations to provide immediate system protection.
• Industrial Durability: Designed for heavy-duty industrial processing environments requiring stable physical sealing.

Applications

• Industrial chemical processing lines.
• Water treatment and hydronic filtration systems.
• HVAC liquid cooling loop monitoring.
• Boiler feed water line supervision.

Technical Specifications

Connections and Interfaces

Installation Guidelines

• Orientation: Mount exclusively in horizontal pipe runs where the paddle assembly hangs vertically downward.
• Upstream/Downstream Clearances: Provide a minimum of five pipe diameters of straight, unobstructed piping upstream and downstream of the switch.
• Flow Direction: Ensure the arrow cast on the switch housing aligns with the actual fluid flow direction inside the pipe.
• Electrical Wiring: De-energize control loops prior to servicing or terminating wires to the SPDT screw terminals.