is placed but would encounter again the sealing means 76 as it attempted to travel between the counterbore 62 and that area of the valve shaft along the sealing means 76 in operation it should be noted that wafer means 76 in carrying out its primary function would be substantially stationary and would not move as the rotation of the valve stem occurs furthermore in theory the sealing mechanism of the wafer accommodates a seal from the vertical to the horizontal that is as noted in the packing material which attempts to seal between the inner wall 43 of counterbore 44 and the packing material this particular primary sealing means i e wafer 76 provides that the seal be transferred to a horizontal seal along the surface between the sealing wafer and the upper structural component that being the case it provides a more effective seal a seal which virtually eliminates any possibility of leakage that is not provided in the use of packing material only fig7 through 9 illustrate a feature of the valve for providing a means for ascertaining when the valve has been moved between open and closed positions as noted fig6 and 7 illustrate the stop member 100 which includes a substantially circular body portion 102 with a pair of flared.