Shanghai Yihuan fluid control equipment Co., Ltd.

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Leakage and solution of regulator

1.  Valve inner leakage, stem length is unwell. Gas open valve, the valve stem is too long upward (or downward) distance is not enough, there is space between causing valve spool and seat, cannot fully contact, lead to shut the lax and internal leakage. Same gas shut stem is too short, led to the space between valve core and seat, cannot fully contact, lead to lax shut and internal leakage.
    Solution: should be shortened (or extend) regulator valve stem makes regulator appropriate length, making its no longer leakage.
2.  Packing leakage. After packing load in stuffing box, through gland to exert its axial pressure. Due to packing plastic, make it produced radial force, and close contact with stem, but the contact is is not very evenly. Some parts contacted loosenly, some parts contacted tightly, even some places no contact. Regulator in use process, there exists relative movement between stem and packing, the movement called axial movement. In using process, with the influence of high temperature and high pressure and strong permeability, the regulator stuffing box is the part with more fluid leak phenomenon. The main reason of causing packing leakage is interface leak, for spinning filler, still can appear leakage (pressure medium along the tiny gaps between packing fiber to external leakage). The interfaces leakage between stem and packing is due to packing contact pressure gradual reduced, stuffing aging causes and pressure medium will along with the gap between stem and packing to external leakage.
    Solutions: to make packing into convenience, in the stuffing box top chamfering, in the stuffing box bottom placed corrosion proof clearance smaller metal protecting ring (and packing contacting surface can not be cant), in order to prevent the packing to push by medium pressure. Stuffing box parts and packing contacting metal surface to finish machining, in order to improve surface finish, reduce packing wear. Choose flexible graphite packing, due to its gas tightness, friction small, after long-term use, changes small, wear loss is small, easy maintenance, gland bolts tighten the friction does not change, pressure resistance and  heat-resistance are good, not affected by the internal medium erosion and stem and stuffing box internal contact metal will not occur corrosion. So, effectively protect the stem stuffing box sealing, guarantee the packing sealing reliability and long-term.
3.  Valve disc, seat deformation leakage. Core, seat leakage mainly because regulator production process casting or forging defects can lead to corrosion strengthening. And the corrosive medium through fluid scouring can also cause regulator leakage. Corrosion mainly in the form of cavitation erosion and existence. When the corrosive medium through the regulator, will produce erosion and shock to valve disc, seat materials and makes core, seat to an oval or other shapes, with the time pass, leading to valve disc, seat don't match, existing gap, and can not tight closed and occur leakage.
    Solution: The key is to select good valve core, seat materials type and quality. Choose corrosion resistant material, to pit, defect product firmly rejects. If the valve core, seat deformation is not very serious, cam through sand grinding, eliminate trace, improve sealing finish, in order to improve the sealing performance. If damaged, should replace the new valve.

2011-05-04

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