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The causes of centrifugal pump mechanical seal leakage
The causes of centrifugal pump mechanical seal leakage are analyzed as follows:

1.Leakage during static pressure test
(1) The sealing end face is damaged, deformed or damaged during installation.
(2) When the sealing end face is installed, not clean it up and contain granular impurities.
(3) The sealing end face is not tightened due to loose or untightened positioning screws, and the gland (the static ring component of the stationary type is the pressure plate) is not tightened.
(4) The precision of the machine and equipment is not enough, so that the sealing surface is not fully fitted.
(5) The seal ring of the rotor and rotor ring is not compressed or compressed enough or damaged.
(6) The rotor and stator ring v-type seal ring is installed in the opposite direction.
(7) If the sleeve is leaking, it is because the seal ring of the sleeve was not compressed or compressed enough or damaged during assembly. Treatment method: inspection and cleaning during assembly should be strengthened, and assembly should be carried out strictly according to technical requirements.

2. Periodic or paroxysmal leakage
(1) The axial channeling momentum of the rotor component is too large. Solutions: adjust the thrust bearing so that the movement momentum of the shaft is not greater than 0.25mm.
(2) Periodic vibration of rotor components. Solutions: find out the cause and eliminate it.
(3) The pressure in the sealing cavity often varies greatly. Solutions: stable process conditions.
3. Frequent leakage

(1) Frequent leakage caused by the sealing end face defects.
A. Spring compression (mechanical seal compression) is too small.
B. The spring compression is too large, graphite moving ring crack.
C. The sealing end face width is too small, and the sealing effect is poor. Solutions: increase the width of the sealing end face and increase the spring force accordingly.
D. The floating performance of the compensation sealing ring is too poor (the sealing ring is too hard or the amount of hardening or compression is too small, and the clearance of the compensation sealing ring is too small). Solutions: if the gap of compensation ring is too small, increase the gap of compensation ring.
E. Leakage of joints of mounting or bonding and static rings (poor mounting process and residual deformation; Uneven material; Adhesive uneven, deformation).
F. Dynamic and static rings are damaged or cracked.
G. The sealing end face is severely worn, and the compensation ability disappears.
H. Deformation of the sealing end face of the dynamic and static rings (the spring force on the end face is too large, and the friction increases, resulting in thermal deformation or partial wear; The structure of sealing parts is not reasonable, strength is not enough, deformation after stress; Due to improper processing technology and other reasons, sealing parts have residual deformation; Uneven force during installation causes deformation. Solutions: replace defective or damaged seal rings.
I. The verticality deviation between the end face of dynamic and static ring seal and the axis centerline is too large, and the relative parallelism deviation between the end face of dynamic and static ring seal is too large. Solutions: adjust the sealing end face.

(2) Frequent leakage caused by auxiliary sealing ring.
A. The sealing ring material is wrong, wear-resisting, corrosion-resisting, temperature-resisting, anti-aging performance is too bad, resulting in premature deformation, hardening, cracking, dissolution, etc..
B. The compression amount of the O-ring is not correct. When it is too large, it is easy to install; the sealing effect is too small.
C. Install the shaft (or bushing) of the seal, the seal end cap and the seal cavity. The surface of the O-ring is burred, the chamfer is not smooth or the corner is not round enough. Solutions: The burr and the non-smooth chamfer should be properly smoothed, the arc and chamfer should be properly increased, and the smoothing should be smoothed.
D. O-ring block, break, damage, edge or distortion. Solutions: clean rubber ring, do not use gasoline, kerosene; straighten when assembling the sealing ring.

(3) Leakage due to spring defects.
a. The spring end face is skewed.
b. Multi-spring type mechanical seal, the free height difference between the springs is too large.
(4) Frequent leakage due to other parts, such as poor quality or looseness of the transmission, tightening and thrust parts.
(5) Frequent leakage due to the rotor, such as leakage caused by rotor vibration.
(6) Frequent leakage due to mechanical seal auxiliary mechanism, such as flushing coolant flow rate is too small or too large; pressure is too small or too large; liquid injection direction or position is wrong; poor injection quality, impurities.
(7) Frequent leakage due to problems with the medium.
a. The medium contains suspended particles or crystals. Due to accumulation for a long time, it is blocked between the moving ring and the shaft, between the springs, between the spring and the spring seat, so that the compensation seal ring can not float and lose the compensation buffering effect.
b. The suspended particles or crystals in the medium are blocked between the sealing end faces, so that the sealing end faces are not well fitted and wear quickly. Solutions: Before starting the vehicle, first open the flushing and cooling valve, then drive and drive the vehicle after a period of time, and then open the large flushing coolant; properly increase the inlet temperature of the medium; improve the effect of medium filtration and separation.