tailieunhanh - GSFC X-673-64-1F ENGINEERING DRAWING STANDARDS MANUAL

Gate valves are classified as either rising stem or nonrising stem valves. For the nonrising stem gate valve, the stem is threaded on the lower end into the gate. As the hand wheel on the stem is rotated, the gate travels up or down the stem on the threads while the stem remains vertically stationary. This type valve will almost always have a pointer-type indicator threaded onto the upper end of the stem to indicate valve position. Figures 2 and 3 illustrate rising-stem gate valves and nonrising stem gate valves. The nonrising stem configuration places the stem threads within the boundary established by the valve packing. | GSFC X-673-64-1F ENGINEERING DRAWING STANDARDS MANUAL August 1994 X-673-64-1F Supersedes GSFC X-673-64-1E July 1991 ENGINEERING DRAWING STANDARDS MANUAL Mechanical Engineering Branch Goddard Space Flight Center Greenbelt Maryland August 1994 National Aeronautics and Space Administration Goddard Space Flight Center Greenbelt Maryland 20771 .

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