questions in recip comp,taper pins,dozing pump,

All interesting questions....

1) Knocking sounds in recip compressors can be due to: liquid carryover, loose piston nut, loose or cracked crosshead, loose valves.

2) Taper pins or dowel pins are steel pins that are used to positivly locate a machine or machine component. Taper pins are often used in the support feet of a machine to locate the machine relative to others, and to make sure it goes back to the same spot if removed. It also can be used to fix a foot so that thermal growth happens relative to that fixed point.

3) Diaphragm condition, and hydraulics, including the hydraulic return valves.

4) Interstage sealing in a centrifugal compressor or turbine is accomplished with labyrinths, very close clearances between a knife edge laby and the shaft. In compressors it is also common to use a knife edge laby on the shaft, and an abraidable (thermoplastic) material insert in the case so that the laby cuts grooves in the abraidable material to improve sealing.

Steve you did miss one other point. Not to knock your reply as it was very good but ther is also carbon build up from burnt oil.