Abstract: Valve assemblies having a valve seat with a conical surface for causing an included O-ring to roll upon and wedge against the conical surface for closing the port when a spherical valve member is forced against the O-ring.

Abstract: Valve assemblies having valve seats and/or valve members with conical surfaces which cause an included O-ring to roll upon and wedge between the valve member and the seat for reliably closing the valve.

Abstract: An automatic air pressure relief and check valve assembly which may be used in combination with a swimming pool filter or separation tank. The valve assembly includes a normally open lower valve which is responsive to the tank's being full of water for closing the lower valve, and a normally closed upper valve which is responsive to air being expelled from the tank through the normally open lower valve for opening the upper valve during times when water is filling the tank. The upper valve may be selectively opened when air is required to enter the tank so that water may be drained from the tank. Preferred embodiments of the upper and lower valves include valve seats having conical surfaces and respective valve members which cause an included O-ring to roll upon and wedge against its conical seat for reliably closing each valve.