The Keckley type 27 double seated float valve is most widely used for automatic control of supply liquids where dead-end closing is not essential and valve inlet pressures are more important. Typical applications are on large and small water storage tanks, oil storage tanks, chemical storage tanks, and other industrial applications.

Available in sizes 1/2", 3/4", 1", 1-1/4", 1-1/2", 2", 2-1/2", and 3"
Maximum inlet pressures vary based upon valve size, 150 PSIG (1/2", 3/4", & 1") to 50 PSIG (3")
The valve typically opens as the float drops with the water level, in reverse operation the valve can open a a level rise to serve as a drainage controller.
Keckley Type 27 Float Valve Specification