Correct installation and use of mechanical seals1

The correct installation and use of the mechanical seal is the key to ensuring long-term stability, safety and reliability. Improper installation and use will result in poor sealing performance, shortened life or seal failure. The following briefly introduces the installation and use precautions for reference:

I. Check: Whether the dimensional accuracy, geometric accuracy and mutual relationship of the relevant parts of the mechanical seal installation meet the requirements.

1. The dimensional tolerance, surface roughness and chamfer transition shape of the shaft and static ring seat matched with the mechanical seal are shown in the following figure;

2. The radial runout of the shaft should be ≤0.04mm, and the axial movement should be ≤0.3mm;

3. The verticality of the joint positioning end of the sealing cavity and the gland facing the axis centerline is less than or equal to 0.04mm;

4. Check whether the axial and radial dimensions of the assembly position of the sealing chamber and the gland are correct.

Second, installation:

1. The assembly size must be guaranteed as required;

2. During the entire installation process, the mechanical seal and the equipment sealing cavity should be kept clean, and it is strictly forbidden to hit or knock, so as to avoid deformation and damage of the friction pair of the mechanical seal and seal failure;

3. The sealing part can be coated with a layer of clean lubricating fluid for smooth installation. It is recommended to use soapy water or silicone ester for ethylene-propylene rubber;

4. When installing the static ring gland, the tightening bolts must be evenly stressed to ensure that the end face of the static ring is perpendicular to the center line of the end cover. Note that the anti-rotation groove on the back of the static ring should be aligned with the anti-rotation pin, but not in the same direction. conflict;

5. When installing the seal related to the rotation direction (such as the coil spring transmission and the hook spring transmission), pay attention to whether the spring rotation direction is correct, and the spring should be tightened as it is rotated;

6. When installing the rotating ring part, when relying on the retaining ring or the impeller or the spring seat to be fixed with the shaft, the working length of the rotating ring part should be ensured. After installation, the rotating ring should be compressed by hand to make the rotating ring flexible in the axial direction. move, and can restore the bit;

7. After installation, turn the shaft by hand to check whether there is a sense of weight. If so, check whether the installation is correct.

Three, use:

1. Before the normal start-up, a static pressure test is required to check the sealing effect of the mechanical seal end face, the sealing ring and the sealing end. If there are any problems, check and solve them one by one.

2. Before normal use, run at normal pressure and temperature for a period of time to make the end face fit more evenly, and then run it under normal working conditions;

3. During work, the sealing chamber should be filled with liquid or sealed medium, keep the end face lubricated, and avoid the phenomenon of evacuation and dry friction.

4. When the temperature of the conveying medium is too high, too low, easy to crystallize or contains impurities, particles, flammable, explosive or toxic, the corresponding flushing and Cooling, filtering, blocking and other measures to ensure the normal operation of the mechanical seal.