Figure 6-19. - Packing installation procedures-Continued.

prevent leakage but must also do this without causing excessive friction and undue wear of the moving part. Although most packing has definite lubricating qualities of its own, lubrication is enhanced by permitting small amounts of liquid or steam to leak past or through the packing. If the pump is used for corrosive or abrasive fluids, then some other form of lubricant, such as grease or oil, must be fed to the packing through external means.

Packing usually takes the form of coils, rings, or spirals. The packing is inserted into a stuffing box fitted around the sliding or rotating joint. The compression of the packing around the joint is controlled by hand-adjusted gland nuts.

The selection of the proper type of packing for a pump is important. There is no general-purpose or all- purpose packing. The specific type of packing that must be used depends on several factors, such as whether the packing seals a rotating or sliding joint and the type of liquid handled by the pump. In any event, you do not have to select the packing. Locally prepared guides and manufacturer's instructions specify what type of packing material to use. Upon receipt of the packing, note its condition and the use