12 inch slurry pump maintenance

How to Choose a Suitable Type of Shaft Seal for Slurry Pump 2 - Support - MIMO Flow Control Co., Ltd

How to Choose a Suitable Type of Shaft Seal for Slurry Pump

Soft packing gland seal

Gland seals are the second most common seal used in slurry applications. The gland seal consists of multiple soft packing rings compressed in a chamber (stuffing box) against a protective wear-resistant bushing mounted on the pump shaft. This type of seal requires continuous liquid lubrication and cooling between the rotating bushing and the compressed packing to prevent overheating due to friction.

Slurry is not a suitable liquid to provide this (lubrication and cooling) function, as the particles can wear out the shaft guard very quickly. Supplemental clean flush water must be provided to flush the slurry particles away from the seal area, while providing the necessary lubrication and cooling required by the packing. The quality, quantity and pressure of this gland sealing water are critical and must be matched to the desired operating conditions as shown.

Machinery Seal

Mechanical seals are not widely used in slurry applications, but their use in special cases is increasing. Mechanical seals consist of stationary and rotating surfaces that fit together under mechanical and hydraulic pressure to prevent leakage.

Alpha grade silicon carbide or tungsten carbide is the most commonly used material for these seal faces.

At present, due to the limited reliability of mechanical seal development and application in this field, special care and attention are required when using mechanical seals in slurry applications. At the same time, the cost of sealing is relatively high and requires a good reason to be used.

Seal specialists are actively developing this type of seal, expecting higher reliability and lower production costs to facilitate increased usage. Mechanical seals are most likely to be used in applications where centrifugal seals cannot be used and where flush water is not available.

The non-flushing mechanical seal is not suitable for all conditions, it has very strict usage requirements:

1) The concentration of the slurry should not be too high, preferably less than 30%. It can work below 40%, above 40% it is not recommended.

2) The temperature of the slurry should not be too high, not higher than 80℃.

3) The particle size of the slurry should not be too large, which will easily affect the work of the mechanical seal.

4) A slurry with no crystals or less crystals is preferred. Crystals can affect the mechanical seal.

5) When the pump is running, the pump cavity should be filled with liquid.

A subtle advantage of the slurry pump design is the fixation of the anti-friction bearings on the rotor. While other manufacturers allow inboard radial bearings to "float" in the housing, slurry pumps hold the bearings in place. This feature, combined with the impeller's short cantilever and oversized shaft, results in a rotating component that is exceptionally rigid and resistant to deflection. In addition, the short shaft length between the fixed radial bearing and the mechanical seal face reduces the likelihood of encountering thermal growth issues that can overstress the seal face. This is critical to provide a mechanical environment that provides the longest lifespan for mechanical seals.