Packings are the traditional method of stopping leakage around the drive shaft of an end-suction centrifugal pump. Rings of braided, fibrous material such as graphite or non-graphitized acrylic, PTFE (polytetrafluoroethylene or Teflon), or other materials are filled into a pump stuffing box (or gland) located on the outside of the pump backplate. However, the gland packing does not stop all leaks. The packing rings are kept loose enough to allow some trickle of liquid to leak out during operation; this provides the necessary lubrication between the inside of the seal face and the outside diameter of the drive shaft to prevent overheating and excessive wear.
The advantages of using packing normally include lower upfront cost, availability, simple installation and minimal downtime. The disadvantages of packing are that it needs to be monitored and adjusted as needed to provide a slow trickle (40-60 drops/minute) to cool and lubricate the area. In addition, the area surrounding the pump must be suitable for a small amount of constant and necessary leakage from the stuffing box, such as removing fluid from the area, or this leak must be constantly drained.
