Gland packing and mechanical seals both are very important components of shafts and pumps. Countless engineering applications rely on these devices to properly function.
Although seals and packings have similar functions, using either depends on budget, personal preferences, and more importantly, application requirements. For example, rotary pumps work best with seals because they are capable of collecting, treating, and filtering fluid leakage. On the other hand, there are applications where a packing is the more appropriate choice, such as settings with corrosive surrounding, which happen to cause seals to deteriorate faster. If this is the case, a packing will last longer.
There are several other pros and cons to using either seals or packing. Below is a short comparison between a gland packing and a mechanical seal.
Gland Packing - Does It Do the Job?
Gland packing is also known as the conventional shaft seal. Many engineers dont recommend packings for a lot of applications due to the requirements and costs of maintenance. Sealing off liquids or gases isnt as effective either, as a packing is prone to occasional leakage. You need to regularly adjust so that the seal is well-lubricated.
There also the problem of abrasive liquids causing corrosion. This usually takes a toll on the life span of a gland packing, thus forcing you to spend more on replacements and repairs.
On the bright side, there are cases where packings out perform seals. They good with handling aggressive fluids, for example. Packing earns another point due to its performance in case there is leakage because its easy to adjust to keep the pump fully functional. You cant do this with seals because you have to take the pump out of service.
Applications that involve ball valves, gate, globe, and valve cocks also go in favour of packing since seals need rotary motion to be able to seal off anything. It is exactly this reason that gland packings are integrated in reciprocating pumps.
Mechanical Seals - What Makes Them Any Good?
When it comes to popularity, seals win. They are implemented in a lot more applications partly because they cause very few leak problems, and they are practically maintenance free.
Sticklers for power consumption may also be inclined to use seals more because they have considerably low energy consumption. Thanks to the few leakages, seals hardly ever experience interruptions, thereby saving time and effort.
Other factors of a seals durability are the duration of the sealing operation, ambient temperatures, and the liquid being pumped. Pressure and temperatures cause gradual damage for both seals and packings, especially with mechanical seals. If seals are your choice for sealing equipment, remember that accidental dry running may make seals deteriorate faster.
The price of seals may also discourage you because they are a lot more expensive than packings.
Which to Choose
At the end of the day, the best way to approach this is choosing the sealing equipment that can get the job done with very few hassles. Whether you choose gland packing or mechanical seals, make an informed decision so that you can prevent snags in your budget and productivity.