Compression packing (gland packing) and mechanical seals are two mechanisms familiar to those in the fluid sealing industry. If you are not familiar with these two products you are not alone. A Google search of “compression packing” may initially result in hits on compact-able luggage. A search on mechanical seals may not return metal-plated robot sea mammals, but the common person may not know what they’re getting.
Compression packing is not compact-able luggage. It is a material used for sealing on mechanical devices, especially valves, pumps, and other types of rotor equipment. Motor boats, for example, have engines with a “stuffing box”, where the rotor passes through. Compression packing is used to seal sea water out of the hull of the boat as it enters the stuffing box. Without compression packing sea water would flood the hull.
Speaking of the sea, let us re-visit seals, mechanical seals. Mechanical seals are devices used to prevent leakage, contain pressure, and protect from contamination. Like compression packing, mechanical seals are a sealing device. Considered an advancement as a sealing device, mechanical seals can be seen as superior to compression packing, but that’s not always the case.
Compression packing vs. Mechanical Seals
Both compression packing and mechanical seals have their strengths and weaknesses. Choosing the appropriate device for your sealing needs really depends on the application. For example, compression packing is the preferred choice if you need a solution that has a lower up-front cost. Also, compression packing is more cost-effective for sealing equipment with larger shaft diameters. In addition, installing compression packing is easier than installing mechanical seals. And compression packing is the preferred choice when dealing with an imperfect mechanical environment, such as slight shaft misalignments.
Mechanical seals do have some advantages. First, they effectively seal more efficiently than compression packing. In other words, they leak less. Since mechanical seals leak less they are the ideal choice for applications dealing with dangerous liquids or gases. Although mechanical seals are much more difficult to install, they require little or no maintenance.
In a Nutshell
Hopefully, this brief introduction to two devices commonly used in the fluid sealing industry has shed some understanding of what these obscure items are. Like everything else in life, there isn’t just one specific solution for all of your sealing needs. Making a choice between compression packing and mechanical seals depends on the application, your resources, and a number of other factors. If you are new to the fluid sealing industry hopeful you have a better idea of what compression packing and mechanical seals are, and are not.