Recognizing this length as a problem the manufacturer did not leave enough room between the face of the stuffing box and the first obstruction, to accommodate some of the modern cartridge double seals or the newest split mechanical seals. This means that the wet end is left on the piping and the power end along with the adapter are brought back to the shop for seal replacement and repair. Unless you have a seal cartridge mounted, or you are using a split seal design, you will have trouble making an initial impeller adjustment with most of the open impeller designs in use today. The direction of adjustment varies with manufacturers. In either case the seal setting is disturbed and short seal life follows.
Most plants have both types of designs that causes confusion with the mechanics.
Although not available for every pump, these adapters can be used to eliminate the need for time consuming and costly alignment procedures. None of the popular pumps are equipped with jack bolts to facilitate the manual alignment and this just compounds the problem. The result is poor seal and bearing performance. All pump manufacturers recognize the short life problem and they install a small rubber ring outboard of the lip seal to try to deflect the water or chemical away from the bearings. Water ingestion is a major cause of bearing failure.