Rising Stem

When the Stem rises, the Valve is opened. Therefore, space is required for opening a "rising stem" valve. The position of Stem indicates whether the valve is open or close. In addition, in the opening position, the thread of stem is not in contact with the fluid, and thus, avoid corrosion.

Non-Rising Stem

For Non-Rising Stem valves, space is not required for operation. However, it would be difficult to determine the valve open/close position by visual, and the thread of the stem may be corroded since it is in contact with the fluid.