How to correctly use pneumatic valve packing

packing is dynamic seal filler material, used to fill the packing room space, in order to prevent the medium leak through pneumatic stem and packing chamber space. Packing is one of the key parts of pneumatic valve products, if you want to achieve good sealing effect, must master the correct method of packing. Not only should notice when select material packing material itself, and the installation of the packing method and from the consideration on the structure of the stuffing box and ensure reliable sealing.
one, common packing varieties
because of the information used for various operating conditions more species of pneumatic valve is the most commonly used in general but several or A dozen
,
packing type A, rubber asbestos packing: XSFXSFXSFXSF;
B, oil banned asbestos packing: YSFYSFYSF;
C, ptfe asbestos packing;
D, flexible graphite braided packing: according to the different respectively of reinforced material and heat-resistant ℃ ℃ ℃ ℃;
E, ptfe woven packing;
F, half metal braided packing, with stainless steel wire, copper wire as the core of asbestos. With a clip wire, stainless steel wire, monel wire and solid wire, nickel, asbestos yarn weaving. According to the purpose of its surface treated with graphite, mica, molybdenum disulfide lubricant. Also some asbestos as the core, with lubrication of copper coated graphite as platinum twist.

, forming filler molding packing of forming its varieties have A and rubber


C B, nylon, ptfe, filled ptfe (
D Enhanced ptfe) Reinforced material for glass fiber, generally for ~ % glass fiber.

E, flexible graphite ring,
on the packing their own requirements, reduce packing friction of pneumatic valve rod;
and prevent packing corrosion of pneumatic valve stem and gland;
and meet the needs of the working condition of medium.
3, note
type, packing, packing cut off. Incision, each lap incision when installation phase fault;
when, at high pressure using ptfe forming filler should pay attention to its cold flow properties;
, flexible graphite ring used alone sealing effect is bad, should with flexible graphite braided packing or YS ( The temperature) Combination of stuffing box in the middle of flexible graphite ring, braided packing, on both ends can be separated layer assembly or a layer of flexible graphite layer braided packing, also can put across the ring in the middle of the stuffing box, spacer ring respectively into two groups of combination of assembly packing up and down;
and graphite have corrosion on pneumatic valve rod stuffing box every use should choose a slow etchant in packing;
, flexible graphite in aqua regia, concentrated sulfuric acid and nitric acid medium shall not apply;
, the precision of the size of the stuffing box surface roughness, pneumatic valve rod size accuracy and surface roughness is the key to influence forming filler sealing;