and discharge cannot be over emphasized. ! ATTENTION ! NOISY VALVES, DUE TO IMPROPER FILLING, CAN LEAD TO SHORT LIFE AND RAPID MECHANICAL WEAR OF THE POWER END PARTS. B. VALVE COVERS A CAUTION A THE VALVE COVERS, AS USED WITH THE NATIONAL OILWELL VARCO PLUNGER PUMPS, MUST BE KEPT TIGHT AT ALL TIMES. DUE TO THE