The DF755 Hydrostatic Head Level Switch is a diaphragm operated "hydrostatic head pressure" level switch. A pressure sensitive diaphragm operates a snap-switch that can be wired directly to electric pilot circuits to control pumps at predetermined levels. The DF755 is designed to start and stop electric driven pump(s) to maintain tank levels. It is also applicable to engine driven pumps. The nitrile sensing diaphragm is impervious to most liquids and is sensitive enough to control levels with 1/4" (6 mm) repeatability. Materials include aluminum body, nylon bottom plate and a special alloy leaf snap-switch as standard. The DF755 is suitable for atmospheric tanks in a non-hazardous area. The SPDT snap-switch for this model is preset for a 4 inch differential in liquid level. Typical applications include salt water disposal systems, cooling towers, crude oil tanks, water/flood systems, diesel day tanks and sumps. SPDT snap switch is rated 5A @ 125, 250 or 480 VAC; 1/2A @ 125 VDC; 1/4A @ 250 VDC. Maximum pressure rating: 25 psi (172kPa [1.72 bar]).