Packning

Packing is one of the most common and simplest seals for positive displacement pumps. Packing typically consists of braided or formed rings that are compressed in the stuffing box of a pump. As the packing is tightened, it squeezes up against the shaft and the stuffing box wall to create the seal.

When the pump is operating, process liquid cools and lubricates the packing. The pump must leak or "weep" slightly to ensure proper lubrication.

Packing is one of the oldest forms of shaft sealing. Original packing was made of materials such as leather or rope. Today, packing materials typically include PTFE or compressed graphite.

Packing is cost-effective ideal for high temperature and thick liquids.

Since a small amount of leakage is required to cool and lubricate packing, this seal type is a poor choice for thin, flammable, toxic, or other dangerous applications.