Mechanical seals are extremely common in the pumping industry - and come in a wide range of materials and options. In its simplest form, a single component mechanical seal has two faces that contact and create a seal. These seal faces are lapped to a smooth, high quality finish. One face rotates with the pump shaft - while the other is held stationary in the pump housing. Once a small amount of process liquid reaches the seal faces, a hydrodynamic liquid film is created - this is what forms the seal and lubricates the faces.

Packing is one of the most common and simplest seals for positive displacement pumps. Packing consists of braided or formed rings that are compressed inside the stuffing box of a pump. As the packing gland is tightened, the packing is compressed against the shaft and the inside of the stuffing box bore - creating a 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.