What Is Pump Packing?
Pump packing refers to packing used in pumps and mainly corresponds to gland packing. A pump consists of a casing, motor, shaft, bearings, blades (including gears and vanes), and a shaft seal. Among these, the pump packing corresponds to the shaft seal.
A shaft runs through the pump casing, and rotating parts such as vanes and gears are attached to the end of the shaft. As the shaft rotates, the liquid is pumped through. Pump packings are used to fill the gap between the casing and the shaft.
Uses of Pump Packing
Pump packings are used in all pumps that have a shaft in the casing. However, some pumps do not have a shaft in the casing. These are magnet pumps.
Magnet pumps have a magnet attached to the end of the shaft and a magnet attached to the rotating element inside the casing. The shaft is not connected to the casing, but instead is magnetically bonded to the casing to create rotation, eliminating the need for a pump packing.
Principle of Pump Packing
When using a rotating device, a gap created by passing a shaft through the casing becomes a problem. Gland packing seals this gap. Gland packing is stuffed into the stuffing box of each device. The stuffed gland packing is tightened with bolts using a packing holder. The force with which the packing presses against the shaft surface provides sealing force, preventing leakage.
If leakage is eliminated, the packing will seize due to friction with the rotating shaft surface. Therefore, the packing is tightened to a certain degree to allow a certain amount of liquid to leak out. In other words, the liquid used is the lubricant. Because of this principle, the gland packing is generally used in water-based pumps and cannot be used with ignitable or toxic liquids.
Mechanical seals are used in environments where the problem of using gland packing cannot be solved. A mechanical seal consists of a rotating ring and a fixed ring that slide against each other and are held in place by a spring. The allowable leakage is as low as 5.6 g/h.