A Guide to Hydraulic Accumulator Maintenance and Operation

Blog | February 6th, 2023

Almost every industrial facility contains hydraulic accumulators. Most facilities have multiple of them, although they often are misinterpreted. Accumulators can be the most hazardous hydraulic components in the mill, not because they are intrinsically harmful but due to a lack of comprehension. Regardless of their function, all hydraulic accumulators store energy and must thus be treated with respect.

Accumulator Functions

A hydraulic accumulator is used for one of two purposes: to increase the system’s volume at a very high pace or to absorb stress. Its precharge determines the function it will carry out. If the accumulator is utilised to add volume to the system, its precharge must be slightly below the maximum system pressure to allow oil to enter. If the accumulator is to be utilised to absorb stress, it must be pre-charged to a pressure near the maximum system pressure, with little or no oil.

Precharging an Accumulator

Dry nitrogen is generally used to precharge an accumulator. Nitrogen does not react negatively with hydraulic oil under pressure, and because it makes up roughly 78% of the earth’s atmosphere, it is the safest and least cheap gas to utilise. The next most prevalent inert gas is argon, which makes up less than 1 per cent of the earth’s atmosphere.

Under no circumstances should oxygen or air be used to precharge a battery. If compressed oxygen or air comes into contact with even a small quantity of hydrocarbon, severe reactions can occur, leading to explosions, fires, employee injuries, and property damage. An accumulator should display a safety sticker that advises against pre-charging with any gas but nitrogen. These stickers are included with brand-new accumulators, although they are frequently removed or painted over.

Utilise a charging system to precharge an accumulator. The precharge should be completed with no oil in the accumulator. Release any pressure at the accumulator inlet. The dump valve on most accumulators may be opened to empty oil into the tank. Screw the charging apparatus onto the Schrader valve of the accumulator and rotate the gas chuck handle clockwise to depress the pin. On the charging device, the current precharge may then be read.

Adding Volume

Volume accumulators feature a pressure dump line when the system is turned off. Without the charging equipment, the precharge may be determined by observing the lowering of the gauge when the system is shut down, and the dump line is opened. The gauge will fall gradually since the dump line is often reduced in size to prevent reservoir disturbance. When the gauge hits the accumulator’s current precharge, it will immediately drop to 0 psi.

This is also useful for determining whether an automated dump valve has opened properly. When the system is shut off, if the gauge goes to 0 psi without a steady decrease, it is probably disconnected from the accumulator, and it will be uncertain if the accumulator has been dumped.

Shock Absorbency

When an accumulator is used for shock absorption, it is undesirable for there to be a significant amount of oil in the accumulator while it is operating. If the compression process has already begun, the accumulator will react more quickly to pressure surges. For this reason, it is generally advised that shock accumulators be pre-charged to almost 100 psi below the actuator’s maximum load pressure.

It is not advised to absorb stress using a piston accumulator. Bladder and diaphragm accumulators are more sensitive since they do not need to overcome the static friction of the piston seal, nor do they need to accelerate or decelerate the mass of the piston.

Mobile Hydraulic Specialties Pty Ltd

Factory 89, 38-40 Popes Road
Keysborough, Victoria, 3173

Phone: (03) 9798-6511

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Mobile Hydraulic Specialties Pty Ltd

Phone: (03) 9798-6511
Address: Factory 89, 38-40 Popes Road, Keysborough, Victoria, 3173