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Triplex Pumps: What are They and What are Their Uses?

Updated on February 22, 2010

A triplex pump is a type of positive displacement pump used in a number of high-pressure applications. Positive displacement pumps work on the principle of gradually reducing the volume of the working fluid and forcing it into a discharge opening, thereby increasing pressure, which results in providing a flow. This pump is a reciprocating pump that uses three plungers or pistons to pump the working fluid, hence the name triplex pump. Pistons are typically used in triplex pumps that are suitable for systems with working pressure of up to 1000 psi, whereas plungers are generally used when the working pressure exceed 1000 psi.

The construction of these triplex pumps is similar to that of a three-cylinder internal combustion engine, with three plungers, or pistons, in three corresponding cylinders. The pumping action is facilitated by the reciprocating nature of the single acting plungers in the cylinders, which work by taking suction of the working fluid on the downwards stroke, while pressurizing as well as discharging on the upstroke.

A single prime mover drives the three plungers, and in many cases, the prime mover is an electric motor. Some other common prime movers used to drive a triplex pump are hydraulic motors and diesel engines. The reciprocating movement of the pistons is achieved through a camshaft. The prime mover drives the camshaft, which in turn causes the three plungers to reciprocate in a specific order so that one plunger discharges for every 120 degrees rotation of the prime mover. Unlike a simplex, single plunger pump that produces an intermittent discharge, the triplex pump provides a smoother flow. In addition, the average flow rate of a triplex pump is significantly higher than that of a simplex or a duplex pump. The volume and pressure achieved by the pump is directly proportional to the prime mover RPM, such that an increase in prime mover RPM causes an increase in the pressure and volume output of the pump.

This type of pump is ideal for applications that require high pressure, and are commonly found in water jet cutting systems as well as adopted in the mud pump role, for both drilling and well-operation industries. A mud pump is a high-pressure pump that is used to circulate drill fluid for cooling the drill.

To locate and contact a triplex pump manufacturer, check out a comprehensive list at


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      robert 16 months ago

      The article provides an understanding of the basic workings and applications of a triplex pump...very good. I was hoping for a cutaway f the fluid end.

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      Chris 5 years ago

      Mud pumps primary purpose is to carrry cuttings out of the hole it is drilling not a cooling system