All gate valves have ______ valve stems.

Gate valves can feature both rising and non-rising stems, which allows for versatility in their application. A rising stem gate valve has a stem that moves upward as the valve opens, making it easy to visually indicate whether the valve is open or closed based on the position of the stem. This design is particularly advantageous in situations where there is enough vertical space above the valve to accommodate the upward movement of the stem.

On the other hand, non-rising stem gate valves are designed for applications where vertical space is constrained. In these valves, the stem does not rise; instead, it provides the necessary motion for opening and closing without changing its position significantly. This is achieved typically through a threaded design where the stem rotates to move up or down within the valve body.

The presence of both types of valve stems showcases the adaptability of gate valves in different environments and system configurations, making them suitable for a wide range of uses in wastewater treatment and other applications. Understanding the differences between the two types of stems is critical for selecting the appropriate valve for specific operational needs in wastewater management.