Triplex Mud Pumps 32 P SERIES PUMPS. National Oilwell offers a full line of triplex mud pumps to handle any drilling requirement.  These tough field-proven models cover input horsepower ratings in the 500 to 2,200 range. The 14-P-220 is the largest member of the P Series of pumps.  It is rated for 2,200 input horsepower at 105 strokes per minute and can accommodate liners and pistons up to 9-inch in diameter. It can deliver as much as 1,215 gallons per minute at a pressure of 2,795 psi, or up to 375 GPM at 7,500 psi.*  The six, P Series models offer a broad selection of fluid end combinations, drive options and other accessories to tailor pumping requirements to your exact needs. ADDITIONAL POWER AND FLUID END FEATURES OF THE P SERIES PUMPS INCLUDE: • One-piece construction of crankshaft, connecting rods and pinion shaft. • Roller bearings throughout. • Two-piece piston rod allows removal of piston without disturbing liner. • Clamps lock liners and piston rod assemblies in place. • Full-circle spray cools and lubricates liners regardless of pump speed. • Metal-to-metal liner retention. • Herringbone gears. SELECT THE FLUID END MODULES THAT EXACTLY MATCH YOUR DRILLING REQUIREMENTS. National Oilwell offers a choice of fluid end modules and valve covers for every P Series pump model. All pump models can be equipped with either the standard or premium forged, two-piece interchangeable fluid modules. HIGH PRESSURE MODULES TO 7,500 PSI. Also available for the 12-P-160 and 14-P-220 mud pumps are high- pressure modules.  These are designed for working pressures up to 7,500 psi (527.4 kg/cm2).  The 12-P-160 modules have smaller internal bores than the standard or premium modules in order to withstand the higher pressures.  The bores for both the 12-P-160 and 14-P-220 high pressure modules, along with premium modules, are autofrettaged to provide improved fatigue life at the higher pres- sures. DURABLE POWER END. P Series power end features include: • Fabricated steel frame construction. • Accepts a variety of drive arrangements, on either or both sides. • Splash lubrication system (dual type on 14-P-220). EASY-TO-SERVICE-FLUID END. Fluid end features include: • Two-piece cylinder modules with complete interchangeability between modules. • Variety of valve covers are offered including a FAST CHANGE screw-type arrangement for quicker removal and installation. • Versatility in suction and discharge piping. FAST-CHANGE. For quicker removal and installation, the FAST-CHANGE valve cover has a simpler screw-type arrangement with no locking wedges. The FAST-CHANGE valve cover can be installed in the field on existing pumps.  No modifications to the module are required for conversion from TAPR-LOK to FAST-CHANGE. Information on OILWELL^® PT series mud pumps can be found on page 37.  National Oilwell’s line of CE mud pumps can be found on pages 38 and 39. TAPR-LOK^TM valve cover FAST-CHANGE valve cover