Packing seal according to its structural characteristics can be divided into:

Soft packing seal

Hard packing seal

Molding packing seal

The packing is usually made of a softer thread, which is filled in the sealing chamber by a square strip with a cross-sectional area. The gland produces a compacting force, which compacts the packing, forcing the packing to press on the sealing surface (the outer surface of the shaft and the sealing chamber), producing a radial force of sealing effect, and thus plays a sealing role.

Occasions suitable for soft packing: the selected materials of packing filler determines the packing sealing effect, generally packing materials is restricted by PH value and the working medium temperature, pressure, and working surface roughness of the machine, eccentric and linear velocity, etc., 

Aramid root is a kind of high strength organic fiber woven into the root and then impregnated with polytetrafluoroethylene emulsion and lubricant. Polytetrafluoroethylene (ptfe) packing root is made of pure PTFE dispersion resin as raw material, then twisted, woven into the packing root. It can be widely used in food, pharmaceutical, paper chemical fiber and other high cleanliness requirements, and a strong corrosive medium valves, pumps.

Hard packing seal hard packing seal has two kinds of open ring and split ring.

Machine seal is always composed of rotating parts (yellow part) and stationary parts (orange part), two relative motion of the moving, static torus as the main sealing surface.

Mechanical seal also known as end seal, according to the relevant national standards defined as: by at least a pair of end face perpendicular to the axis of rotation in the fluid pressure and compensation mechanism of the elastic (or magnetic force) action and auxiliary seal under the cooperation to keep the stick while combining with relative sliding, and preventing fluid leakage device.

Dry gas seal "dry running gas seal" is a new type of shaft end seal which uses slotted seal technology for gas seal and belongs to non-contact seal. Features: good sealing performance, long life, no need for sealing oil system, low power consumption, simple operation and low maintenance cost. Dry gas seal is the main-body seal of high speed centrifugal compressor in petrochemical industry, which does not need any seal end cooling and lubrication oil. Application: high speed and high speed fluid machinery such as centrifugal compressor, suitable for a small amount of process gas leakage into the atmosphere without harm, such as air compressor, nitrogen compressor, etc.

Labyrinth seal is to set a number of successively arranged circular sealing teeth around the rotating shaft, and a series of closure gaps and expansion cavities are formed between the teeth. The sealed medium can produce throttling effect and achieve the purpose of preventing leakage through the gap of tortuous labyrinth.

Honeycomb labyrinth seal’s  seal tooth welded into a honeycomb shape, to form a complex shape of the expansion chamber, its sealing performance better than the general seal form, suitable for the occasions with big pressure difference, such as centrifugal compressor balance disk seal. The manufacturing technology of honeycomb labyrinth seal is complicated, the sealing strength is high and the sealing effect is good.

Oil seal is a self-tightening type with lip shape, its simple structure, small size, low cost, easy maintenance, resistance torque small, can not only prevent medium leakage, also can prevent external dust and other harmful substances entry, and have certain compensation ability to wear, but not resistant to high pressure, so commonly used in the chemical pump on occasion.

Helical seal is also a form of dynamic seal, it is in the rotating shaft or in the shaft on the housing processing spiral groove, between the shaft and the housing filled with sealing medium. The rotation of the shaft causes the spiral groove to act like a pump, thus preventing the leakage of the sealing fluid. The size of its sealing capacity and screw Angle, pitch, tooth width, tooth height, tooth length and the size of the clearance between the shaft and sleeve. Due to the lack of friction between the seals, the service life is long, but due to the limitation of structure space, the screw length is generally shorter, so its sealing capacity is also limited. In the use of pump speed, its sealing effect will be greatly reduced.