External factors affecting the mechanical seal of self-priming centrifugal pump are as follows:1. The deflection of the pump shaft is too large - when the shaft is bent and deformed, the linear displacement of the cross-section centroid in the direction perpendicular to the axis is called deflection, and the mechanical seal requires a uniform force between the two seal faces. However, due to the unreasonable planning of self-priming centrifugal pump products, the deflection at the mechanical seal device is too large, resulting in uneven force at the seal, which will cause the self-priming centrifugal pump to lose its sealing function.2. Too large vibration - the large vibration of the mechanical seal is often not caused by the mechanical seal itself, but by the unreasonable design of the pump shaft, poor machining accuracy, large rear wheel parallelism, large radial force, etc. So we should set the time, strictly check and eliminate the oscillation source.3. There is no auxiliary scouring system or the planning of auxiliary scouring system is unreasonable - the auxiliary scouring system of mechanical seal is very important. It can effectively protect the sealing surface and play the role of cooling, smoothing and flushing sundries. Sometimes the planner's plan is unreasonable, and the sealing effect cannot be achieved. Some plan auxiliary systems, but because there are impurities in the flushing fluid, flushing. The brush fluid flow is large, the pressure is not good, and the brush position planning is unreasonable, which also can not achieve the effect.4. Axial displacement of pump shaft - the specific pressure of mechanical seal surface achieves the purpose of sealing, and the sealing degree at both ends can be adjusted through bandage spring. In order to ensure this specific pressure, the pump shaft does not need to have too many grooves.The above are the external factors that affect the mechanical seal of self-priming centrifugal pump. I hope it can help you.