Functionally, pipeline shut-off valves can be classified as follows:
- Shut-off valves. These valves are used for shutting off or closing the flow of operating liquid or gas to a certain degree of seat tightness;
- Flow control valves. These valves are used to regulate the flow rate of a liquid or gas by controlling the process parameters (pressure, temperature, etc.);
- Distributing and mixing valves. They are used for the distribution of operating liquid or gas flows according to the set directions or for mixing such flows;
- Safety valves. Safety valves (or pressure relief valves -PRV) are intended for pipelines and equipment automated protection from prohibitive pressure surges by releasing the excess liquid or gas pressure;
- Shutdown valves. These valves are actuated valves designed to stop the flow of a hazardous fluid upon the detection of a dangerous event. They provide protection against possible harm to people, pipelines, equipment, or the environment that might result from an inadmissible or not provided by the process change of parameters or operating liquid or gas flow direction, and for shutting down the flow;
- Phase separator valves (condensate trap, air trap, oil separators). These valves are used for an automated separation of the operating fluid depending on its state and phase.