WHAT ARE THE ADVANTAGES OF MECHANICAL SEALS COMPARED WITH GLAND PACKINGS

The mechanical seal is a device for preventing fluid leakage, which is consists of at least one pair of end faces perpendicular to the axis of rotation, under the joint action of fluid pressure and elastic force (or magnetic force) of the compensation mechanism, and the cooperation of the auxiliary seal ring, the pair of end faces remain attached and relatively slide.

The elastic loading mechanism and auxiliary seal are mechanical seals of metal bellows, which we call metal elastomer bellow seals. Among the light-weight seals, there are rubber bellows used as auxiliary seals. The rubber bellows has limited elasticity, and generally needs to be supplemented with springs to meet the loading elasticity. In addition to the bellow seals, there are spring seals, pump seals, etc.

Gland packings refers to a dynamic sealing device that generates a pressing force between the packing and the rotating part and the fixed part through the pre-tightening or self-tightening effect of the medium pressure. There are many structural forms, mainly composed of packing, packing box and packing fixing parts. Commonly used filler materials are asbestos fabric, carbon fiber, rubber, flexible graphite and engineering plastics, etc., and adopt multi-ring or spiral multi-layer structure. The packing box is used for packing. Packing fixing parts include gland, bolt and spring, etc., which are used to tighten the packing, preventing medium leakage when working.

In order to make you understand the advantages and disadvantages of the mechanical seal more clearly, we compared the mechanical seal with the soft packing seal. The following is the result of the comparison.

1. Higher Reliability of Mechanical Seals

The reliability of the mechanical seal is higher than that of the soft packing seal. During long-term operation, the mechanical seal will show a stable sealing state with only a small amount of leakage. According to statistical data, the leakage of the mechanical seal is only 1% of that of the soft packing seal, which shows that the reliability of the mechanical seal is better.

2. Longer Service Life of Mechanical Seals

The service life of the mechanical seal is very long. The working time in neutral liquid media can reach more than 2 years, the working time in oil media can reach more than 1 year, and it can also work long in the environment of chemical media, which is more than half a year.

3. Better Wear Resistance Performance of Mechanical Seals

The friction power of the mechanical seal is small, and the wear on the bearing and the shaft sleeve is small. Generally speaking, the friction power of the mechanical seal is less than one-half of the friction consumption of the soft packing seal, and the bearing and the shaft sleeve are basically not worn.

4. Wider Range of Application of Mechanical Seals

The material of the mechanical seal determines that the mechanical seal can adapt to the working environment of high temperature, low temperature, high pressure and high speed. The mechanical seal has anti-corrosion ability and can be used for sealing of corrosive media and media containing abrasive particles. In addition, the mechanical seal has strong anti-vibration capability and is insensitive to vibration, deflection and tilt response.

5. The Process Requirements of Mechanical Seals are Higher.

Compared with the soft packing seal, the mechanical seal has higher requirements on the manufacturing process and more complex design structure. Therefore, the installation and replacement of the mechanical seal requires the operator to have a certain technical level. This feature of the mechanical seal determines its high price, high one-time investment, and the difficulty of handling accidents.