The check valve, also known as the cut-off valve, is a forced sealing valve. When the valve is closed, pressure must be applied to the disc to force the sealing surface not to leak. The opening and closing part of the globe valve is a plug shaped valve disc, the sealing surface is flat or conical, and the valve disc moves in a straight line along the center line of the seat. The diameter of the stem is usually larger because the force to close the valve is greater than the force to open it.