Use a 4-inch-to-2-inch bushing to reduce the PVC pipe, then reduce it further using a 2-inch-to-1-inch reducing fitting. Make a handle from two 1-foot lengths of 1-inch-diameter PVC pipe and a 1 ...

The idea is to reduce the 3-inch (air tank) and 2-inch (barrel) pipes to fit the 1-inch solenoid valve openings. Use iron pipe nipples to connect the solenoid valve to the PVC fittings on the air ...