What are the 2 types of gate valves?

Rising stem gate valves: These gate valves have a stem that rises above the valve to indicate whether the valve is open or closed. When the valve is closed, the stem is fully extended and when the valve is open, the stem is fully retracted.

Non-rising stem gate valves: These gate valves have a stem that does not rise above the valve. Instead, the stem is threaded into the gate and rotates with the gate as it opens or closes. Non-rising stem gate valves are often used in applications where space is limited or where the valve is located underground.