a) Shut-off: Used to isolate the medium in a pipeline. Examples include gate valves, globe valves, ball valves, plug valves, and butterfly valves. b) Check: Prevents backflow of the medium. Example: check valve.
c) For regulation: to adjust pressure and flow. Examples include control valves, pressure-reducing valves, throttling valves, butterfly valves, V‑port ball valves, and balancing valves, among others.
d) Distribution valves are used to change the flow direction of the medium in piping systems and to distribute the medium. Examples include distribution valves, three‑way or four‑way ball valves, and plug valves.
e) Safety applications: Used for overpressure safety protection, such as safety valves and relief valves.
f) Other special-purpose valves, such as steam traps, air vents, drain valves, vent valves, breather valves, sludge discharge valves, and temperature‑control valves.
1.2 Classified by Drive Type
a) Automatic valves: Operate by the inherent energy of the fluid itself.
b) Actuated valves: including manual, electric, pneumatic, and hydraulic types.