Pneumatic valves are used in packing at most

the pneumatic valve is most used in compression packing - a according to the different conditions of use, the combination of various materials made of rope, disc and seal ring; The second is the flexible graphite packing. Packing correct installation is the only way to ensure the sealing surface is not damaged. Packing correctly installed, should be installed in the packing parts in good condition, well forming, pneumatic valve stem packing precast artists in the open position ( Except for on-site maintenance) Under the condition of. Before installation, no graphite asbestos packing should be coated with a layer of flake graphite powder, packing should be kept clean, graphite, sealant can not be mixed with sundry. Who can fit in pneumatic valve stem top packing pneumatic valve, should try to adopt the method of directly set into the. Set into the former, first remove bracket, hand wheel, lever and other gear, with higher than that of pneumatic valve stem pipe pressure, pressure filler. Will not be used to directly into the set of, packing should be cut into overlapping forms ( This form can be used for flexible graphite packing, but to ban the herringbone packing, to avoid the o-ring. ） And will take the mouth staggered up and down. Sideways against packing set in pneumatic valve stem, and then recover from top to bottom, make the incision anastomosis, gently into the stuffing box. Device within the gland packing should be placed a circle a circle, and round by pressing pressure, pressure evenly. Packing incision lap joint position of the circle should be staggered °. In the installation of the first lap at the bottom of the packing should be carefully check whether level off, packing mat is installed. Packing during the installation process, be apart ~ circle should be pneumatic valve rod, a rotating pneumatic stem and packing lest bite dead, pneumatic valve opening and closing. Basic after filling, packing gland compaction of stuffing. The strength should be uniform, when using gland bolts on both sides to tighten, assuming sole responsibility for its profit and loss shall not put the packing gland crooked, so as to avoid the uneven of packing and pneumatic valve rod friction. Gland of pressure casing pressure into the depth of the stuffing box / ~ / for its height, also can use packing ring height as the packing gland into the depth of the stuffing box, generally leave shall not be less than mm preloaded gap, then check that the pneumatic valve stem and packing gland, packing gland and packing of clearance at four o 'clock. Rotary pneumatic valve stem, pneumatic valve stem should be flexible operation, normal force, no jam phenomenon. If the force is too large, should be appropriate to relax a little packing gland, reduce packing hold force of pneumatic valve stem. V packing and die forming of pneumatic valve stem packing ring should be the top set up slowly, set style to prevent the inner ring by pneumatic valve stem thread cut. V packing packing cushion under convex Angle upward, mounted on the underside; Packing in the concave Angle downward, convex Angle upward, placed in the middle of the stuffing box; On the packing of the concave Angle downward, plane upward, stuffing box is placed in the upper. A split ring packing should be measured in advance good stuffing box depth and the location of the split ring; Split ring to alignment and flow nozzle, allowing a little partial, not allowed to offset. Used in pneumatic valve stem o-ring for the o-ring groove; Used in pneumatic device for outer o-ring groove on the piston, they all belong to dynamic seal form. Dynamic sealing o-ring installation, for installation of chamfering, thread and groove part of the application of special tools; The o-ring tensile axis, the installation sliding surface should be smooth and the lubricant, o-ring should be quickly to groove. Shall not use rolling method, method of hand drawing will o-type trap into the slot. O-ring into the groove shall be no distortion, relaxation, defects such as scratches, generally it stop after a period of time, let the restored prototype for the o-ring can cover. Have o-ring structure of retaining ring, when installation shall not remove the retaining ring. （ O-ring compression deformation rate is % ~ %) 。 In the installation of the packing, it is strictly prohibited to small generation. In the case of improper packing width, allowing than packing instead of stuffing box slot wide mm - mm; Not allowed to use a hammer to beat, application of flat stone roller or even flattened. Installation, packing pressure and packing should be according to the medium pressure performance factors to determine. Under normal circumstances, the same conditions of rubber, ptfe and flexible graphite packing with a small compression force can be sealed, and asbestos packing with large clamping force. （ Packing pressure force should be on the premise of guarantee seal, minimize) 。