2 1/2" Air Release Valve Double Float. VS9766Flanged PN16, Epoxy Coated Ductile Iron Body & Bonnet, ABS Float Rated PN16, Temperature 10C to 70C. Air release valves with double floats are used in water supply systems, sewage systems, irrigation systems, and other fluid applications where the presence of air can disrupt the flow or efficiency of the system. They help maintain system performance, prevent air lock, and ensure the smooth operation of pipelines and equipment.