Allen-Bradley 840-D1 Float Switch

The Allen-Bradley 840-D1 is a Style D automatic float switch rated for up to 600 VAC, 250 VDC, and 10 A, designed for tank-operation liquid level control in industrial systems. It reacts to liquid level changes by opening or closing its contacts, featuring a low operating force and standard contacts housed in a Type 1 enclosure for rugged industrial environments. The 840-D1 is positioned for switching pumps, motors, alarms, or indicators in storage tanks, water treatment, and wastewater facilities. It uses stainless steel float assemblies, rods, and cables, part of Rockwell Automation’s Bulletin 840 family of heavy‑duty level switches, and is offered with the 840 family’s range of operator assemblies and enclosure options. This Style D configuration is specifically described as a general-purpose float switch with tank operation only, suited to installations that require a compact, reliable level sensor with straightforward wiring. Certifications for many 840 products include UL Listed, CE marking, UKCA marking, and CSA certification in various markets, reflecting broad regulatory compliance. Operating sensitivity typically falls in the 2–5 inch (50.8–127 mm) range, depending on installation and fluid properties, enabling simple integration with level-control schemes in tanks and vessels. With its Type 1 enclosure and standard contacts, the 840-D1 delivers a robust, straightforward solution for level control where a rugged, reliable float switch is needed.