Mechanical seals and gland packing are integral parts of all pumps and shafts and used in many engineering applications. Both types of seals are used commonly and it depends upon budget, requirements and personal choice. However, there are differences in features of the two types of packing and one must make a prudent choice to have fewer maintenance costs and prevent other snags that commonly surface with the wrong selection. Let us make a quick comparison between mechanical seal and gland packing.
For starters, a gland packing, which is also called a conventional shaft seal is not commonly preferred by engineers because of the requirement of maintenance. Leakage is the most common problem that surfaces every now and then. It requires adjusting so that there is necessary lubrication of the seal. Then there is the problem of corrosion because of abrasive liquids. This often reduces the working life of the seal making one spend on new seal. However, there are circumstances when packed gland is the ideal option as when dealing with aggressive fluids. Another feature in favor of packed gland is that in case of a leakage, it can be adjusted keeping the pump in service where as this is not possible in the case of a mechanical seal as pump has to be taken out of service.
Mechanical seals are thus more popular in diverse applications. They are more common because they are virtually maintenance free and users face very few leakage problems. Life expectancy of a mechanical seal is also dependent upon liquid being pumped, duration of operation and working temperatures. Both mechanical seals and gland packing are prone to wear and tear as they are subject constant pressures and temperatures. Especially in case of mechanical seals, accidental dry running can lead to destruction of the seals.
One feature that goes in favor of mechanical seals is their low consumption of energy. Because there are very few leakages, there are rare interruptions and thus savings that can be substantial over a period of time.