Classification of automatic control valves

Transferred from Baidu Baike. Classified by purpose and function: a. Two-position valves: mainly used to shut off or connect the medium； 　　b. Control valve: Mainly used for regulating the system. When selecting a valve, it is necessary to determine the flow characteristic of the control valve ； 　　c. Shunt valve: used for distributing or mixing media ； 　　d. Isolation valve: Usually refers to a valve with a leakage rate of less than one in 100,000. 　　 Classification by main parameters 　　　　1 Classification by pressure 　　(1) Vacuum valves: Operating pressure below standard atmospheric pressure ； 　　(2) Low-pressure valve: Nominal pressure PN ≤ 1.6 MPa ； 　　(3) Medium-pressure valve: PN2.5～6.4MPa ； 　　(4) High-pressure valve: PN10.0～80.0 MPa, usually PN22, PN32 ； 　　(5) Ultra-high pressure valve: PN≥1000 MPa. 　　2 Classification by operating temperature of the medium 　　(1) High-temperature valves: t＞450℃ ； 　　(2) Medium-temperature valve: 220℃≤t≤450℃ ； 　　(3) Normal-temperature valve: –40°C ≤ t ≤ 220℃ ； ④Low-temperature valve: –200°C ≤ t ≤ –40°C. 　　 Common classification method: This classification method divides items based on both principles and functions as well as structure, and it is the most widely used method at both the domestic and international levels. They are generally divided into nine major categories: Direct-acting pneumatic control valves (1) Single-seat control valves ； 　　(2) Two-seat control valve ； 　　(3) Sleeve control valve ； 　　(4) Angular control valve ； 　　(5) Three-way control valve ； 　　(6) Diaphragm valve ； 　　(7) Butterfly valve ； 　　(8) Ball valve ； 　　(9) Eccentric rotary valve. The first 6 are linear stroke, and the last 3 are angular stroke. 　　These nine products are also the most basic ones, and are also known as ordinary products, base products, or standard products. All kinds of special and dedicated products are developed as improvements and variations based on these nine categories of products. 　　 Classified by main special purposes (i.e., special and dedicated valves) 　　　(1) Soft-seal shut-off valve ； 　　(2) Hard-sealed shut-off valve ； 　　(3) Wear-resistant control valve ； 　　(4) Corrosion-resistant control valve ； 　　(5) Fully fluoroplastic corrosion-resistant control valve 　　(6) Fully corrosion-resistant alloy control valve ； 　　(7) Emergency shut-off or vent valve ； 　　(8) Anti-clogging control valve ； 　　(9) Corrosion-resistant anti-clogging shut-off valve ； 　　(10) Insulated jacket valve ； 　　(11) High-pressure drop cut-off valve ； 　　(12) Low-flow control valve ； 　　(13) Large-diameter control valve ； 　　(14) Large adjustable ratio control valve ； 　　(15) Low-S energy-saving control valve ； 　　(16) Low-noise valve ； 　　(17) Miniature control valve ； 　　(18) Linered (rubber, PTFE, ceramic) control valves ； 　　(19) Ball valve dedicated for water treatment ； 　　(20) Valves dedicated for caustic soda ； 　　(21) Special valve for phosphatic ammonia ； 　　(22) Chlorine control valve ； 　　(23) Bellows-sealed valves…… Classified by driving energy 　　　　(1) Pneumatic control valves ； 　　(2) Electric control valve ； 　　(3) Hydraulic control valve.