PC-2500Z1, 2 1/2" Expansion Plug, Concave, Zinc

These plugs seal by pressure exerted by the concave bottom against the walls of the plug, much in the same manner as a belleville washer. Concave bottom plugs should be driven on the inside bottom radius and not from the top rim of the cup. The driving arbor should be .015/.0125" smaller than the inside diameter of the plug, and have a contact radius of .062", with a flat bottom to prevent contact with the concave bottom to avoid deforming this surface.