Why do mechanical seals for centrifugal pumps leak?Mechanical seals, also known as face seals, which is a pair or more pairs of perpendicular to the shaft of the dynamic and static ring contact surface, in the pump under the joint action of the medium pressure and compensating spring force, to keep close to the relative rotation, to prevent liquid leakage from the contact surface of the sealing device. Mainly used in pumps, compressors, hydraulic transmissions and other similar equipment for the sealing of the rotating shaft. Its main function is to change the easy leakage of axial seal to the more difficult leakage of end face mechanical seal. During the working process, a layer of very thin liquid film is formed between the dynamic and static rings, on the one hand, to realize the role of sealing medium, on the other hand, to play a lubrication, reduce the effect of friction vice wear.
The dynamic ring of the mechanical seal consists of O-ring, spring, drive seat and fixed bolts, which is fixed on the drive shaft and rotates with it. The static ring is mainly composed of O-ring and anti-rotation fixing bolt, which is fixed on the seal gland, and it is static with the pump casing as a whole. Mechanical seal installation is completed, mainly by the pressure of the medium in the pump and the spring force of the spring on the moving ring mechanism under the joint action of the moving ring tightly pressed on the static ring. When the pump is running, the dynamic and static ring by the media or flushing liquid between the formation of a very thin liquid film, to realize the seal without leakage, which is the main seal of the mechanical seal. In addition, the seal static ring and seal gland, seal gland and pump casing, shaft sleeve and pump shaft, shaft sleeve and dynamic ring seal between the main O-ring to achieve.
From the above mentioned mechanical seal of the main leakage points are five:
(1) the seal between the shaft sleeve and the shaft, belongs to the static sealing point; (2) the seal between the shaft sleeve and the shaft, belongs to the static sealing point.
(2) the seal between the dynamic ring and the sleeve, belongs to the static sealing point; (3) the seal between the dynamic ring and the sleeve, belongs to the static sealing point.
(3) The seal on the contact surface between the dynamic ring and the static ring, which belongs to the dynamic sealing point; and
(4) The seal between the static ring and the mechanical seal gland, belonging to the static sealing point.
(5) The seal between the mechanical seal gland and the pump body is a static sealing point.