{"product_id":"honeywell-fs4-3s-liquid-flow-switch","title":"Honeywell FS4-3S Liquid Flow Switch","description":"\u003ch3\u003eDescription\u003c\/h3\u003e\n\u003cp\u003eIndustrial fluid process monitoring requires resilient hardware, and the \u003cstrong\u003eFS4-3S\u003c\/strong\u003e 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 \u003cstrong\u003eFS4-3S\u003c\/strong\u003e (Part Number \u003cstrong\u003e114641\u003c\/strong\u003e \/ \u003cstrong\u003eFS4-3S\/U\u003c\/strong\u003e) is engineered to withstand corrosive process fluids where standard brass components would degrade.\u003c\/p\u003e\n\u003cp\u003eThe 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.\u003c\/p\u003e\n\n\u003ch3\u003eFeatures\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eCorrosion-Resistant Construction:\u003c\/strong\u003e Built with a stainless steel body and Monel bellows to handle aggressive or brackish liquids safely.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eFlexible Switching:\u003c\/strong\u003e SPDT electrical contact structure supports both normally open and normally closed wiring profiles.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eMechanical Actuation:\u003c\/strong\u003e Responds accurately to fluid velocity variations to provide immediate system protection.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eIndustrial Durability:\u003c\/strong\u003e Designed for heavy-duty industrial processing environments requiring stable physical sealing.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eApplications\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003eIndustrial chemical processing lines.\u003c\/li\u003e\n  \u003cli\u003eWater treatment and hydronic filtration systems.\u003c\/li\u003e\n  \u003cli\u003eHVAC liquid cooling loop monitoring.\u003c\/li\u003e\n  \u003cli\u003eBoiler feed water line supervision.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eTechnical Specifications\u003c\/h3\u003e\n\u003ctable\u003e\n  \u003ctbody\u003e\n    \u003ctr\u003e\n      \u003ctd\u003e\u003cstrong\u003eManufacturer\u003c\/strong\u003e\u003c\/td\u003e\n      \u003ctd\u003eHoneywell\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd\u003e\u003cstrong\u003ePart Number \/ Model\u003c\/strong\u003e\u003c\/td\u003e\n      \u003ctd\u003eFS4-3S (114641 \/ FS4-3S\/U)\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd\u003e\u003cstrong\u003eBody Material\u003c\/strong\u003e\u003c\/td\u003e\n      \u003ctd\u003eStainless Steel\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd\u003e\u003cstrong\u003eBellows Material\u003c\/strong\u003e\u003c\/td\u003e\n      \u003ctd\u003eMonel\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd\u003e\u003cstrong\u003eSwitch Contact Configuration\u003c\/strong\u003e\u003c\/td\u003e\n      \u003ctd\u003eSPDT (Single Pole Double Throw)\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd\u003e\u003cstrong\u003eWeight\u003c\/strong\u003e\u003c\/td\u003e\n      \u003ctd\u003e0.9 kg\u003c\/td\u003e\n    \u003c\/tr\u003e\n  \u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003ch3\u003eConnections and Interfaces\u003c\/h3\u003e\n\u003ctable\u003e\n  \u003cthead\u003e\n    \u003ctr\u003e\n      \u003cth\u003eTerminal Designation\u003c\/th\u003e\n      \u003cth\u003eFunction\u003c\/th\u003e\n    \u003c\/tr\u003e\n  \u003c\/thead\u003e\n  \u003ctbody\u003e\n    \u003ctr\u003e\n      \u003ctd\u003eCommon (C)\u003c\/td\u003e\n      \u003ctd\u003eLine input connection\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd\u003eNormally Closed (NC)\u003c\/td\u003e\n      \u003ctd\u003eOpens contact on liquid flow increase\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd\u003eNormally Open (NO)\u003c\/td\u003e\n      \u003ctd\u003eCloses contact on liquid flow increase\u003c\/td\u003e\n    \u003c\/tr\u003e\n  \u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003ch3\u003eInstallation Guidelines\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eOrientation:\u003c\/strong\u003e Mount exclusively in horizontal pipe runs where the paddle assembly hangs vertically downward.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eUpstream\/Downstream Clearances:\u003c\/strong\u003e Provide a minimum of five pipe diameters of straight, unobstructed piping upstream and downstream of the switch.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eFlow Direction:\u003c\/strong\u003e Ensure the arrow cast on the switch housing aligns with the actual fluid flow direction inside the pipe.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eElectrical Wiring:\u003c\/strong\u003e De-energize control loops prior to servicing or terminating wires to the SPDT screw terminals.\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Honeywell","offers":[{"title":"Default Title","offer_id":52705340555627,"sku":"FS4-3S\/U","price":100.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0953\/3227\/0443\/files\/fs4-3s-5zz0celeg0h_b3e8552b-313f-44af-88e8-267c8ff4275f.jpg?v=1766640972","url":"https:\/\/www.plcprotech.com\/id\/products\/honeywell-fs4-3s-liquid-flow-switch","provider":"PLC ProTech Ltd.","version":"1.0","type":"link"}