1. What are the requirements for the inspection of the auxiliary sealing ring of the mechanical seal?
1) The surface of the auxiliary sealing ring is smooth and flat, without defects such as bubbles, cracks, and gaps; the size of the end face should be uniform; the burrs of the “o”-shaped sealing ring should be at an angle of 45 degrees to the working surface;
2) The hardness of the auxiliary sealing ring should be selected according to the pressure. The higher the sealing pressure, the higher the hardness; the lower the sealing pressure, the lower the hardness. Synthetic rubber is commonly used for auxiliary sealing rings;
3) The inner diameter of the “o”-shaped sealing ring that seals the cylindrical surface should be 0.5-1mm smaller than the outer diameter of the sealing point. The inner diameter of the “o”-shaped sealing ring of the moving ring is relatively small, and the inner diameter of the “o”-shaped sealing ring of the static ring is smaller than that of the static ring;
4) The compression amount of the auxiliary seal should be appropriate.
If the compression amount is too large, the sealing effect is good, but the friction resistance is large, the assembly is difficult, and the swimming compensation ability during work is poor.
If the amount of compression is too small, the frictional resistance is small, the assembly is easy but the sealing effect is poor. The “O” rings of the dynamic and static rings of the mechanical seal are all cylindrical seals, and their compression is about 8% – 23% of the diameter of the transverse smooth surface. If the diameter is small, take a percentage; if the diameter is large, take a small percentage.
5) The compression amount of the “o”-shaped sealing ring should consider its other functions.
For example, for a static ring without an anti-rotation pin, the “O”-shaped sealing ring of the static ring plays a dual role of sealing and anti-rotation. The compression of the “O”-shaped sealing ring should be larger to prevent the static ring from rotating and seal failure.
On the premise of ensuring the sealing effect, the “O”-shaped sealing ring of the moving ring should have a smaller compression amount to avoid excessive compression and excessive resistance that cannot be compensated for floating.
2. What is included in the inspection of the mechanical seal spring?
The inspection of the spring includes the total number of turns, the number of effective turns, the free height, whether the shaft center is perpendicular to the end face, and the direction of rotation of the spring.
Single springs must check the handedness, multiple springs do not need to check the handedness.
Check the original free height of the new spring, measure the free height, and compare it with the original record, and replace it if the residual deformation is too large.
After the old spring is cleaned, measure its elasticity, and replace it if the elasticity is reduced by 20%.
Multi-spring mechanical seal, the free height difference of each spring shall not be less than 0.5mm.
