The two share the same basic pumping principal: a plunger is pushed into a closed chamber to raise pressure and expel fluid through an outlet check valve; as the direction of the plunger is reversed, low pressure fluid enters the chamber through an inlet check valve. The difference between them is only how the plunger is moved. The crank or direct drive pump uses a crank similar to the one in an automobile engine.
The intensifier drives the plunger with a hydraulic cylinder usually with oil.
The intensifier pump is not as efficient and is more costly to operate than the direct drive pump. It has pressure ripples and is noisy, but it does have a longer seal life and is more suited to 24-hour operations using multiple independent nozzles. The crank drive pump is quieter, uses less water and power and is more straight forward to maintain. It is the better option for environments where operating costs and profitability are important.
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