Pfeiffer Balzers Oil Fluid Lubricant Felt Reservoir with O-Ring for Turbomolecular High Vacuum Pumps TPH/U 180H, 190, 240, 450H and 520. The lubricant reservoir should be replaced at least every three years. Where extreme operating conditions or unclean processes are involved, the replacement should occur more frequently. See AVAILABLE DOWNLOADS PDF below for replacing Oil Fluid Lubricant Reservoir. Pfeiffer Part Number PM 063 265 T.