1.The axial force is too large. Mechanical seal in the use of the process is not able to bear the axial force, if there is axial force, the impact of mechanical seals is serious. Sometimes the axial force is not balanced due to the unreasonable design of the pump's axial force balance mechanism and the reason of its manufacture, installation, use and so on. Mechanical seal under an axial force, running gland temperature will be high, the polypropylene medium at high temperature will be melting, so the pump start soon after losing the sealing effect, the sealing face discontinuous spray leakage phenomenon of stationary pump.
2.Pump shaft deflection is too large. Mechanical end face seal, contact a rotating axial seal, it is in the fluid medium and the function of the elastic element, two perpendicular to the axis line of the seal tightly, the relative rotation, so as to achieve the sealing effect, thus requiring two to seal between the uniform stress. However, due to the design of pump product is not reasonable, pump shaft running, in the mechanical seal installation of large deflection, so that the force between the sealing surface is not uniform, resulting in poor sealing effect.
3.There is no auxiliary flushing system or auxiliary flushing system is not reasonable. Mechanical seal auxiliary flushing system is very important, it can effectively protect the sealing surface, to play the role of cooling, lubrication, washed away debris, etc.. Sometimes the designer not reasonable allocation of auxiliary flushing system, not up to the sealing effect; although sometimes has designed auxiliary system, but because of the impurity washing liquid, washing fluid flow, the pressure is not enough, rinse mouth position design unreasonable, also did not reach the sealing effect.
4.The vibration is too large. Mechanical seal vibration is too large, resulting in the loss of sealing effect. But the mechanical seal excessive vibration causes are often not the mechanical seal itself and other parts of the pump are the origin of the vibration, such as submersible sewage pump shaft design is not reasonable, the processing precision is not enough reason, bearing and coupling parallel to the difference, radial force and other reasons.
5.Pump cavitation causes. Because of the unreasonable operation system and an inlet of the pump cavitation performance is not good, the pump speed is high, the local occurrence of cavitation in the pump inlet, cavitation, water bubbles will, on the one hand it will impact the mechanical sealing surface of the outer surface, so that the surface is damaged; on the other hand will make the flow dynamic membrane anastomosis the ring also contain bubbles, can not form a stable film flow, caused by dynamic and static ring anastomosis surface dry friction, mechanical seal device damage.
6.Mechanical processing accuracy is not enough. Machining accuracy is not enough, there are many reasons, some mechanical seal itself is not enough processing accuracy, this reason is easy to cause people's attention, it is easy to find. But sometimes the pump parts of the processing accuracy is not enough, this is the reason, not easy to cause people's attention. For example: a pump shaft, a shaft sleeve, a pump body, sealing cavity to increase the accuracy and other reasons. The existence of these reasons for the mechanical seal of the sealing effect is very unfavorable.
