Fluid Power Journal

Calculating Intensifier Ratio for Given Pressure and Flow

Intensifiers boost pressure by pumping hydraulic fluid with a larger bore piston into a smaller bore cylinder to extend the rod. The intensifier can be powered using either air or hydraulics.

Air over oil hydraulic intensifiers convert a high volume, low-pressure air input source to a low volume, high-pressure source of hydraulic fluid. Intensifiers are used for hydraulic presses, hose crimpers, and flaring tools in shops where the cost of a hydraulic pressure source would be prohibitive. Where an intensifier is used to intensify the pressure, the degree of intensification is equal to the ratio of the larger area to the smaller area.

The flow rate at the output of the intensifier will be the inverse ratio of the areas of the pistons. An input piston with an area of 4 units and an output piston area of 0.5 units would have a ratio of 8:1. The output flow would be 1/8 that of the input flow. 

The circuit shown in Fig. 3-36 illustrates a two pressure booster system with oil returns for low and high-pressure oil sources. Valve A is actuated to extend and retract the press cylinder at the bottom of the circuit, while Valve B is used to actuate the high-pressure booster piston. The degree of intensification equals the ratio of the areas of the larger booster piston to the area of the smaller booster piston.

Fig. 3-36 Intensifier System with an Air-Oil Return Tank

Fig. 3-36 Intensifier System with an Air-Oil Return Tank

To determine the intensified pressure use:


To calculate the reduced output flow from an intensifier, it is necessary to multiply the input flow by the area ratio of the small piston to large piston, as described in the text above.

Test Your Skills

1. A 250 mm bore hydraulic cylinder operates a press and develops a force of 900 kN. The fixed displacement hydraulic pump advances the cylinder. At 1.4 MPa a sequence valve opens to provide flow to a hydraulically powered intensifier which boosts the pressure to the cylinder. The bore size of the intensifier output piston is 12 mm and the bore size of the intensifier’s input piston is 40 mm. At what pressure should the hydraulic pressure relief valve be set in order to achieve the correct output pressure from the intensifier?

A. 0.02 MPa.
B. 0.54 MPa.
C. 1.6 MPa.
D. 14.4 MPa.
E. 18.3 MPa.

See Solution

C. 1.6 MPa.

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