The purpose of sealing is to prevent the objects from being damaged, and to have the effect of shock proof, pressure reduction and sound insulation. According to the understanding of this small edition, there are many sealing methods, each of which is different. Today, this small edition will explain the difference between packing seal and mechanical seal and the comparison between them. If you want to know about children’s shoes, hurry up and follow the pace of this small edition. Let’s have a look!
The packing seal is to compress the packing through the packing gland to make the packing deform and contact the outer surface of the shaft to prevent the liquid from flowing out and the air from being sucked into the pump. The tightness of the packing seal can be controlled by adjusting the tightness of the packing gland. The reasonable tightness should make the liquid leak out from the stuffing box in drops, which should be controlled at about 15 to 20 drops per minute. When the delivery temperature of low-pressure centrifugal pump is less than 40 ℃, graphite packing or butter infiltrated cotton packing is commonly used; When conveying liquid with temperature less than 250 ℃ and pressure less than 1.8MPa, use graphite impregnated asbestos filler; When transporting petroleum products with temperature less than 400 ℃ and allowable working pressure of 2.5MPa, asbestos core packing shall be wrapped with metal foil.
Structure and working principle of mechanical seal: the sealing device composed of the end faces of the static ring and the moving ring which are bonded to each other and make relative rotation is called mechanical seal, also known as end face seal.
The mechanical seal is a device for preventing fluid leakage, which is composed of at least one pair of end faces perpendicular to the rotation axis, which are kept in contact and relatively slide under the action of the fluid pressure and the elastic force (or magnetic force) of the compensation mechanism and the cooperation of the auxiliary seal. The auxiliary seal of the compensation ring is a metal bellows mechanical seal. Mechanical seals are mainly used in various series of centrifugal pumps and pumps.
Composition of mechanical seal: it mainly includes the following four types of components. a. Main seals: moving ring and stationary ring. b. Auxiliary seal: sealing ring. c. Pressing parts: spring and push ring. d. Transmission parts: skip seat and key or fixing screw.
Classification of mechanical seals:
According to the rotation or static of the spring element, it can be divided into: rotary internal flow non-equilibrium single end seal, referred to as rotary type; Static external and internal flow balance type single face seal, referred to as static type. According to the fact that the stationary ring is located inside or outside of the sealing end face, it can be divided into internal type and external type. According to the leakage direction of sealing medium, it can be divided into internal loss and external flow.
According to the unloading caused by the medium at the end face, it can be divided into balanced type and non-equilibrium type. According to the logarithm of sealing end face, it can be divided into single end face and double end face.
According to the number of springs, it can be divided into single spring type and multi spring type. Classified by elastic elements: spring compression type and bellows type. According to the structure of non-contact mechanical seal, it is classified as hydrostatic seal, hydrodynamic seal and dry gas seal. According to the temperature classification of the sealing chamber: high, medium, ordinary and low temperature sealing. Separation according to the pressure of the sealing chamber: ultra high, high, medium and low pressure mechanical seals.