What is your opinion about the classification of the gas valve

Gas Valve widely used, a wide range of classification more. The total can be divided into two categories:
The first automatic valve: to rely on the ability of the gas itself and the action of the valve. Check valve, control valve, pressure reducing valve.
Second class driver valve: valve with manual, electric, pneumatic maneuvers. Such as gate valves, globe valves, throttle valves, butterfly valves, ball valves, plug valves.
In addition, the classification of the valve the following ways:
Characteristics of the structure, the direction of movement relative to the valve seat can be divided according to the closure of parts:
1 cut-off door-shaped: the closure member is moved along the seat center.
2 gate-shaped: the closure member to move along the vertical seat center.
3 cocks and ball: shut down parts of the plunger or ball rotation around itself centerline.
Swing shape: Close-axis rotation of pieces around the outside of the seat.
5 coned disc: Close the disc member, rotating around the axis of the valve seat.
6 slide valve shape: off pieces sliding perpendicular to the direction of the channel.gas valve China Manufacturer
By structural Category:
Plug valves, gate valve, globe valve, ball - used to turn on or off the flow of gas pipeline. Check valve (bottom valve) - used to automatically prevent backflow of gas pipe.