1. According to structure, categories of plug valves
can be classified into cylindrical plug valves and conic plug valves.
2. Materials of seal face
(1) Non metal sealed plug valves: Seal face of plug valves is made of PTFE, rubber, nylon, PPL, flexible graphite and other soft materials.
(2) Metal sealed plug valves: The material of seal face is metal.
(3) Oil Slick sealed plug valves: Utilize grease to seal.
3. Working pressure
(1) Vacuum plug valves: Working pressure is lower than standard atmospheric pressure.
(2) Low pressure plug valves: nominal pressure≤1.6MPa; Class 150LB
(3) Medium pressure plug valves: nominal pressure: 2.5~5.4MPa; Class 150-400LB
(4) High pressure plug valves: nominal pressure: 10.0~80.0MPa; Class 500-2500LB.
4. Working temperature
(1) High temperature plug valves: temperature>450℃
(2) Mesotherm plug valves: temperature=120℃
(3) Normal temperature plug valves: temperature=-40℃
(4) Low temperature plug valves: temperature=-100℃
(5) Ultralow temperature plug valves: temperature≤-100℃
5. Face to face
(1) Flanged plug valves
(2) Internal thread plug valves
(3) External thread plug valves
(4) Welded plug valves
(5) Clip plug valves
(6) Cutting ferrule plug valves
Seal principle of plug valves
Based on the different structures and materials of seal face, plug valves adopt metal seal, grease seal and non metal seal. When using metal seal, beside low surface roughness and accurate geometric tolerance, high seal specific pressure is also needed to realize seal. When using grease seal and non metal seal, accurate shape is needed. For the requirements, sealing pair has various structures and seal principle is different.
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