Plug valve with flow area equal to or greater than the flow area of the connected piping

The valve apparatus, comprising:

• a valve body having an inlet port and an outlet port having a seat opening;
• and a plug valve rotatably mounted in the valve body having a cylindrically curved sealing face wherein the inlet port comprises an entry region having a change in outline shape but no change in total area.

A valve apparatus, comprising:

• housing means having an inlet port and an outlet port having a seat opening;
• and sealing means rotatably mounted in the housing means having a cylindrically curved sealing face and a substantially planar second face opposite to the curved sealing face.

A valve apparatus, comprising:

• housing means having an inlet port and an outlet port having a seat opening;
• and sealing means mounted in the housing means having a cylindrically curved sealing face, wherein the inlet port comprises an entry region having a change in outline shape but no change in total area.

A method of improving flow is a valve assembly including a valve body having an inlet port and an outlet port having a seat opening, comprising:

• rotating a plug mounted in the valve body having a cylindrically curved sealing face and a substantially planar second face opposite to the curved sealing face, wherein the plug is moveable between an open position and a closed position, so that in the open position the second face of the plug is aligned with a substantially vertical corner surface located towards the inlet port and a substantially vertical seat edge located towards the outlet port.