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Maintenance of mechanical seals for pumps
- Jul 06, 2018 -

At present, in the production safety requirements and environmental protection requirements, the use of mechanical seals has become more and more extensive, industrial, enterprise dynamic equipment are used mechanical seals to ensure that there is no leakage between the static and dynamic sealing surface. Industrial pumps and chemical pumps with a wide range of mechanical seals, models are also different, but the leakage point is mainly five: ① sleeve and shaft between the seal; The seal between the ② movable ring and the sleeve;

Seal between the ③ and the static ring, the seal between the ④ static ring and the stationary ring seat, and the seal between the ⑤ seal end cover and the pump body. In general, the shaft sleeve extension of the axle between the seal end cover and pump body leakage is more easily found and resolved, but need to observe carefully, especially when the working medium is liquefied gas or high-pressure, toxic harmful gases, relatively difficult.

The rest of the leak intuitively difficult to identify and judge, in the long-term management, maintenance practice on the basis of the leakage symptoms of observation, analysis, research, in order to get the correct conclusion, and correct use and maintenance.

1 Installation of mechanical seals Mechanical seal operation and the length of life depends on the conditions of the equipment itself, so careful inspection of the equipment before the installation of mechanical seals will reduce the possibility of sealing failure and maintenance costs.

The equipment must be inspected from the following aspects: 1.1 Sealing cavity aperture and depth size should be the same as the size of the sealed assembly drawing, the general deviation is ±0.13mm; the dimension deviation of the shaft or sleeve is ±0.03mm or ±0.00mm-0.05. Axial channeling is checked, the total axial channeling cannot exceed 0.25mm, and the radial runout of the shaft is generally less than 0.05mm.

The radial runout is too large, it may cause: the wear of shaft or sleeve, the leakage between the sealing surface increases, the vibration of the equipment intensifies and the life of the seal is reduced. 1.2-axis Bending degree inspection. The maximum bending degree of the shaft should be less than 0.07mm. The surface of the sealing cavity is beat and the surface of the sealing cavity can not beat more than 0.13mm. The sealing cavity surface, if not perpendicular to the shaft, may cause mechanical seals a series of faults. Because the seal gland is bolted to the seal gland, the seal chamber is too big, causing the gland to install tilt, in turn, resulting in a sealed static ring tilt, resulting in the entire seal is not normal shaking, which is the main cause of micro-vibration wear, in addition to mechanical seals and shaft or sleeve auxiliary seal wear will also be intensified, Then there is the abnormal shaking of the seal will also cause metal bellows or transmission pins wear and fatigue, resulting in premature sealing failure.