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Seal Friction Of Gate Valve

The soft seal gate and the stem nut are connected with the T-nut type and the whole embedded 2 kinds of structure. T-shaped nut type structure is simple, the nut and the brake board have adjustment clearance, can simplify the manufacturing process of the gate board, reduce the requirements, but long-term use, will appear T-shaped nut wear bad brake board rubber layer situation, exposing the iron core and lead to rust.Gate Valve

AWWA C509, AWWA C515 recommend this structure. The whole embedded structure is complex, there is no adjustment gap between the nut and the gate, the manufacturing process of the brake board is complex, and the machining and assembling precision of each part is high, but the structure is reliable and the rubber layer wear is not present. This structure is recommended by the CJ/T 216 standard.Gate Valve

AWWAC509 and AWWAC515 recommend this structure. The whole embedded structure is complex, there is no adjustment gap between the nut and the gate, the manufacturing process of the brake board is complex, and the machining and assembling precision of each part is high, but the structure is reliable and the rubber layer wear is not present. This structure is recommended by the cj/t216 standard.Gate Valve

The 3rd O-Ring reduces pressure at the gland, at the same time can realize the pipeline in the case of media pressure to replace the above 2 seals (AW WA C509 4.4.6.3.3) It is dangerous to replace the stem seals and fillers with pressure and therefore not recommended. In the water supply industry do not recommend the use of stuffing structure type, especially in the direct-buried gate valve, not allowed to use, because the stuffing structure needs to be used in the external water lubrication, stem seals can not use asbestos and other materials.Gate Valve

O-Ring sealing structure of the valve stem machining accuracy and surface roughness accuracy requirements than the packing structure is higher, otherwise there will be cutting O-ring situation. The trapezoidal thread of the stem should be extruded, with high surface hardness and small friction coefficient. The rubber material, process and performance requirements must conform to the standard, otherwise rubber aging will affect the valve life, recommended EPDM (EPDM rubber). Valve stem limit design into step type, it is necessary to consider to facilitate the third SEAL ring assembly, can also be designed as a combination.Gate Valve