Hydraulic accumulator


As the name implies, this device is capable of storing energy of liquid in form of pressure. This pressure energy is utilized suddenly or in intermittent manner in machine parts like hydraulic cranes or lifts. 


It consists of of large vertical hollow cylinder in which ram can slide through. The ram can slide in up - down direction. The ram is fitted with bulk load at its top end. A pressurized water inlet at the bottom end of cylinder is provided. Through this inlet high pressure water enters the cylinder which forces the ram to move upward against the bulk weight. 

On the other side of cylinder, there is outlet pipe which is connected to machine like hydraulic lift or cranes. when the machine does not require water pressure, the ram keeps on moving upward because of inlet liquid pressure. At the topmost point of ram, enough pressure energy is accumulated in the accumulator.

When machine requires large energy, the accumulator supplies the liquid under high pressure and ram starts moving downward.

There is a expression to determine the maximum capacity of hydraulic accumulator. This is nothing but the maximum amount of hydraulic energy that can be stored in accumulator. This is simply known as capacity of accumulator.

The work done in lifting the ram = Capacity of accumulator

A = area of sliding ram
W = bulk load on the ram and also weight of ram
P = Pressure of liquid from inlet
L = Lift of the ram by pressure "P"

Now,                        W = P X A   ---------------------- (1)

Work done to lift the ram = W X L  --------------------(2)
There fore on substituting equation (1) in equation (2) we get,

                                 work done = P x A x L

Also we know that Area x Length = Volume 

CAPACITY OF ACCUMULATOR = P x ( A x L ) = P x Volume

This relation will be helpful in solving numerical problems. One of such type is provided below for your practice.

Q > The water is supplied at pressure of 18 N/Cm^2 to an accumulator. The ram has diameter of 2 meter. If the total ram lift is 6 meter, the find:

1 ) Accumulator capacity
2 ) Total weight on the ram

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