What is a Hydraulic Intensifier or Pressure Booster?
A pressure intensifier is a device that is used to increase the pressure in a hydraulic circuit to a higher value, than that of provided by pump.
Principle of operation of Hydraulic Intensifier:
It takes the high volume, low-pressure flow from the pump and converts a portion of this flow to a required value of high pressure. A pressure intensifier is analogous to a step-up transformer in electrical power transmission, which receives, low voltage and high current and converts it into high voltage and low current.
|Principle of Hydraulic Intensifier
It should be in mind that pressure intensifier does not change the power, but changes the form of the power i.e. from low-pressure high volume to high-pressure low volume. Neglecting the losses, the pressure-flow product at the inlet to intensifier is the same as the pressure-flow product at the outlet.
The principle of operation of an intensifier is illustrated in the above sketch. As shown in the sketch, besides on larger side piston,
F = P1 X A1
And on smaller side piston this force gets applied to the fluid present in the chamber. Hence pressure developed in that chamber is,
P2 = F/A2
From these two equations, we can say
P2 = P1 X A1 / A2
And thus, P2 = (A1/A2) X P1
In other words, the output pressure is multiplied by the ratio of areas. Thus higher the ratio of the bigger piston area to the smaller piston area, the higher the pressure intensification will be.
Intensifiers often have pressure ratios ranging up to 50, so they find most useful applications where the pressure required is much higher than are obtainable from a pump, as in high-pressure presses, testing machines, etc.
Types of Intensifiers
Depending upon the construction and working medium the following types of intensifiers are used.
- Single-acting intensifier
- Double-acting intensifier
- Air Oil intensifier
Let us discuss all these three types of intensifiers in detail.
Single Acting Intensifier
A single-acting intensifier is shown in the figure below.
|Single Acting Intensifier
Construction and Working of Single Acting Intensifier
Single Acting Intensifier consists of a low-pressure chamber of a comparatively bigger area and a high-pressure chamber of a smaller cross-sectional area. It has a piston with two active areas.
The larger end of the on is in the low-pressure chamber and the smaller end of the piston is in the high-pressure area.
The low-pressure fluid exerts a force on the piston equal to Pp X A i.e. pump pressure into a bigger piston area. The same force is transmitted to the smaller side piston. However, since the area in the high-pressure side is smaller, higher pressure is developed in this chamber by the same force.
Double Acting Hydraulic Intensifier
A double-acting intensifier is shown in the figure below.
|Double Acting Intensifier
Construction and Working of Double Acting Hydraulic Intensifier
The double-acting intensifier consists of a large piston with a piston rod extending to both sides of the piston. The larger area of the piston is exposed to the low-pressure fluid, and the piston rod is connected to the high-pressure side, on both sides of the piston.
When low-pressure fluid enters either side of the big piston, it causes the movement of the piston. The movement of the piston results in the movement of the piston rod, forcing the fluid out at intensified high pressure.
A double-acting intensifier is symmetrical, about the vertical centerline. Thus, the movement of the on in either direction results in an intensified fluid output from any of the two outlet ends.
Thus, a double-acting intensifier simulates the operation of the two single-acting intensifiers.
An Air-Oil intensifier is shown in the figure.
Construction and Working of Air Oil Intensifier
In an air oil intensifier, the low-pressure oil is replaced by pressurized air. The air exerts its pressure on the bigger area piston, causing it to move.
The movement of the cylinder causes the fluid in the booster chamber to get forced out due to the motion of the piston rod. Some types of air-oil intensifiers are capable of producing an output hydraulic pressure of 200 bar.
As shown in the figure Air-Oil intensifier consists of an air cylinder and a booster cylinder.
It is noteworthy that the construction on the airside is lighter, whereas the construction of the hydraulic fluid side is more sturdy. Heavy-duty V-type sealing is used to seal between air and oil chambers.
Air oil intensifiers are mainly used for clamping devices, since air is readily available from a common source, in industries; other applications include press
operations and punching machines
The air-oil intensifier can be used conveniently in explosive atmospheres, as there is no need for electrical equipment.