SHUT-OFF VALVE Russian patent published in 2001 - IPC

FIELD: metallurgical, chemical and power industries. SUBSTANCE: valve body accommodates seat and shut-off member with a seal. Control rod of shut-off member is coupled to pneumatic control cylinder and sealed by means of bellows. Optimal value of external diameters of bellows crimp space is selected from relation , where D_b is external diameter of bellows crimp space, mm; D_c is average diameter of seat contact with shut-off member seal, mm; S is width of seat contact zone with cut-off member seal, mm; P is operating pressure in valve, MPa; P_cont is control pressure in pneumatic cylinder, MPa; D_p is diameter of pneumatic cylinder piston, mm; K = K₁·K₂·K₃ is generalizing empiric coefficient; K₁ = 0.8-1.2 is coefficient taking into account parameters of coating and roughness of seat surface; K₂ = 1-2 is coefficient taking into account physical parameters of medium to be sealed (at t = 20 C), K₃ = 0.8-1.2 is coefficient taking into account physical characteristics of sealing material. Shut-off valve construction provides for seal tightness at emergency shut-off of control pressure. EFFECT: enhanced reliability and durability. 2 cl, 1 dwg