Valves and Strainers
The gate valve is the most frequently used valve in piping systems. It is a general service valve that is used primarily for on-off, non-throttling applications.
The globe valve is used almost exclusively for throttling or flow modulation. Also, globe valves will only work in one direction.
Check valves work automatically and most are not controlled by a person or any external control; accordingly, most do not have any valve handle or stem.
Ball valves are given their name by the nature in which they operate, where an internal ball with a bored through the centre is rotated to either allow or prevent flow through the valve.