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Comparison of soft packing and mechanical seal

15 Apr 2022Email

Water pump soft sealing packing, commonly known as soft packing, is a kind of new sealing packing made of non-asbestos polymer material. A very thin liquid film is generated between the cylindrical slider and the relative moving surface of the shaft. Due to the special material of the soft filler, the frictional heat generated is close to zero. Therefore, it is one of the fillers with the smallest frictional resistance in the world, and the action of the polymer barrier agent between the fillers ensures no leakage between the media. Therefore, this kind of filler is the only one that is plastic, low-friction and does not require cooling water to flush the water pump filler.

The mechanical seal for water pump 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 action of fluid pressure and the elastic force (or magnetic force) of the compensation mechanism, and is matched with an auxiliary seal to prevent leakage. The common mechanical seal structure is composed of static ring (static ring) 1, rotating ring (moving ring) 2, elastic element 3, spring seat 4, set screw 5, rotating ring auxiliary sealing ring 6 and stationary ring auxiliary sealing ring 8 and other components , the anti-rotation pin 7 is fixed on the gland 9 to prevent the stationary ring from rotating. Rotating rings and stationary rings are often also referred to as compensating rings or non-compensating rings depending on whether they have axial compensating capabilities.


Item Pump packing

Soft packing

Machanical Seal

1. Cheap

2. Simple installation

1. No cooling water required

2. Energy saving

3. Non-grinding shaft sleeve

4, can be repaired online

5. Easy installation and maintenance

6. Reduce wear and tear, long service life

7. Basically no leakage

8. Reusable, long-term economical

1. Basically no leakage

2. No damage to the shaft

3. Low power consumption


1. Leak

2. cooling water, consumption of water.

3. Pollution caused by leakage.

4. Damaged shaft sleeve

5. There are many varieties in stock.

6. Power consumption

7. Short service life

  1. Not suitable for high temperature and high pressure sealing.

1. The installation is difficult, the requirements are high, and it is easy to cause damage during the installation process.

2. The supply is not timely.

3. It is difficult to replace.

4. Once damaged, the leakage is difficult to control, and it is easy to cause the bearing to burn out.

5. Large size cannot be produced, and the price is expensive.

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