Installing The Seal And Identifying Causes Of Seal Leakage

A successful seal installation requires operation of the pump within the manufacturer's specification. Relative movement between the seal parts or shaft sleeve usually indicates that mechanical motion has been transmitted to the seal parts from misalignment (angular or parallel), endplay, or radial runout of the pump (see Figure 46).

Angular misalignment results when the mating ring is not square with the shaft and will cause excessive movement of internal seal parts as the primary ring follows the out-of-square mating ring. This movement will fret the sleeve or seal hardware on pusher type seal designs. Angular misalignment may also occur from a seal chamber that has been distorted by piping strain developed at operating temperatures. Damage in the wearing rings can also be found here if the pump seal chamber has been distorted.

Parallel misalignment results when the seal chamber is not properly aligned with the rest of the pump. No seal problems will occur unless the shaft strikes the inside diameter of the mating ring. If damage has occurred, there will also be damage to the bushing at the bottom of the seal chamber at the same location as the mating ring.

Excessive axial endplay can damage the seal surfaces and cause fretting. If the seal is continually being loaded and unloaded, abrasives can penetrate the seal faces and cause premature wear of the primary and mating rings. Thermal damage in the form of heat checking in the seal faces because of excessive endplay can occur if the seal is operated below working height.

Radial runout in excess of limits established by the pump manufacturer could cause excessive vibration at the seal. This vibration, coupled with small amounts of the other types of motion that have been defined, will shorten seal life.

Instructions and seal drawings should be reviewed to determine the installation dimension or spacing required to ensure that the seal is at its proper working height (see Figure 47). The installation reference can be determined by locating the face of the seal chamber on the surface of the sleeve and then measuring along the sleeve after it has been

TABLE 4 Typical properties of common seal face material
Survival Treasure

Survival Treasure

This is a collection of 3 guides all about survival. Within this collection you find the following titles: Outdoor Survival Skills, Survival Basics and The Wilderness Survival Guide.

Get My Free Ebook

Post a comment