The main causes of leakage from hydraulic machines, pumping systems, sumps and gearcases are wrong choices of shaft seals, poor installation and lack of proper maintenance. The use of the o ring is also common in the shaft seals.
One of the best ways of overcoming this problem is through careful selection of high-quality shaft seals. Some factors must be considered when choosing high-quality shaft seals. Read on to find out more about these factors.
The preferred shaft speed is the function of the shaft run out, finish, shaft concentricity, housing bore, type of seal material and type of medium being sealed.
Temperature is also another factor to consider when choosing a high-quality shaft seal. The temperature range of the seal elastomer must be lower or equal to the temperature range of the medium where seal installation takes place.
Pressure is also another factor to consider when choosing a high-quality shaft seal. You must select shaft seals that withstand both very low-pressure and high-pressure applications. This kind of shaft can offer pressure relief if needed.
Shafts with a hardness of 30 RCs or more have longer seal life regardless of whether they are exposed to abrasive contamination or not.
Shaft surface finish
Most efficient and reliable sealing is achieved with maximum shaft surface finishes. The spiral lead and direction of the finish tool marks affect the sealing efficiency. The best sealing results are obtained with ground or polished shafts with concentric finish marks.
When the shaft centers and bore are not aligned properly, you will experience shorter sealing life because the wear or any form of damage will be concentrated on one side.
Shaft and Bore Tolerances
You must also consider shaft and bore tolerances when choosing a high-quality shaft seal. The best seal result is obtained when there are shaft and bore tolerances.
You must also consider run out when choosing a shaft seal. Make sure the runout is maintained at the minimum. The shaft whip and the bearing wobble cause the center of rotation to move. In addition to inappropriate alignment, this problem is worsened.
Last but not least, you must also consider lubricant medium when choosing a high-quality shaft seal. Seals present superb results when they are consistently lubricated with oils that are compatible with the seal lip material and that have correct viscosity for the application.
So the seal-oil incompatibility should not be ignored if you want to achieve the best sealing performance.