Avoid installation errors and improve mechanical seal performance and service life

Mechanical seal is a shaft seal device that relies on a pair or several pairs of end faces that are perpendicular to the shaft for relative sliding under the effect of fluid pressure and the elastic force (or magnetic force) of the compensation arrangement, and is equipped with auxiliary seals to prevent leakage. It is a shaft sealing equipment for rotating fluid machinery, which can be used in centrifugal pumps, reactors, compressors and other equipment. Since there is a circumferential gap between the shaft and the equipment cavity, the equipment medium leaks from it, so it is necessary to set up a leakage blocking device to seal and block the leaking medium. Because the mechanical seal has the advantages of less leakage and long service life, it has become the main shaft sealing method and is also called the end face seal.u200bu200b

Mechanical seals are one of the basic mechanical components with precision and complex structure. They are the key components of various pumps, anti-chemical pumps, mechanical seals, synthetic kettles, turbo compressors, submersible motors and other equipment.

Its sealing performance and service life depend on many factors, such as model selection, machine accuracy, correct installation and use, etc. Mechanical seals are very strict in terms of manufacturing accuracy or installation accuracy. If they are installed improperly, it will affect the life and sealing performance of the seal, and in severe cases, the seal will quickly fail.u200bu200b

Installation method of mechanical seal:

1. Check the model of the mechanical seal to be installed, whether the specifications are correct, and whether the parts are missing.u200bu200b

2. Check whether the components are damaged, especially whether the sealing end faces of the moving ring and the static ring are bruised. If any damage is found, it needs to be repaired or replaced with new parts, and each sealing element needs to be cleaned with gasoline or kerosene Clean, keep the surface of each component free of dust and foreign matter.u200bu200b

3. Whether there are burrs, groove marks, etc. on the surface of the shaft or the shaft sleeve, the inner wall of the sealing cavity, and the inner surface of the sealing end cover. If burrs and grooves are found, they should be smoothed, polished, and cleaned with gasoline or kerosene to keep them clean, and no dust and debris are allowed to adhere to the surface.u200bu200b

4. Do not use unclean cloth or cotton gauze to scrub the surface of the moving ring and the static ring, but use clean and soft gauze, absorbent cotton and the like to scrub.u200bu200b

5. It should be kept clean during the assembly process to ensure that the sealing end faces of the moving ring and the static ring are not scratched or broken. Apply oil on the matching surface to avoid dry friction at the moment of startup.u200bu200b

Mechanical seals should pay great attention to avoid installation deviations during installation:

1. Tightening the gland should be carried out after the coupling is aligned. The bolts should be evenly supported to prevent the end face of the gland from being deflected. Use the plug mechanical seal to check all points with a full scale, and the error is not greater than 0.05mm.u200bu200b

2. Check that the matching clearance (ie concentricity) between the gland and the shaft or the outer diameter of the shaft sleeve should be uniform, and use a feeler gauge to check that the tolerance at each point is not greater than 0.01 mm.u200bu200b

3. The amount of spring compression should be carried out according to the regulations. It is not allowed to be too large or too small, and the error is required to be 2.00 mm. If it is too large, it will increase the specific pressure of the end face and accelerate the wear of the end face. If it is too small, the specific pressure will be insufficient and the sealing effect cannot be achieved.u200bu200b

4. After the moving ring is installed, it should be able to spring back automatically after pressing the moving ring against the spring.u200bu200b

After the mechanical seal is installed, it cannot completely guarantee its safe operation. Because its influencing factors are various, it should be paid attention to when the rotor is used due to certain reasons (such as shaft bending, bearing wear, etc.) When vibration occurs, it will cause great damage to the mechanical seal, so the rotor should be in good operating condition.u200bu200b

Whether there are shearing or extrusion problems when the auxiliary sealing ring is installed. Since the auxiliary sealing ring is usually a rubber ring and the material is relatively soft, it is often cut or scratched by burrs, steps, keyways and other parts on the shaft during installation. Therefore, attention should be paid to the cleaning of the shaft before installation. If necessary grease can be applied to the shaft before installation. During installation, attention should also be paid to make the auxiliary sealing ring stress evenly, so as not to be squeezed out and fail during installation.