Seal life is very difficult to determine on equipment in the field because operating conditions are unknown, and they vary considerably. It’s hard to define a “typical” application. Furthermore, the applications are usually not ideal (defined as clean lab type environments, fully lubricated, low speed, ambient temps, no pressure, no misalignment or runout, no exposure to chemicals or solids, everything is sized correctly, etc), and the reality is that these factors change seal life considerably.