What is a Hydraulic Accumulator and How Do They Work?

Hydraulic accumulators are energy storage devices. Similar to how rechargeable batteries work in electrical equipment, accumulators discharge energy from the pressurised fluid they store and are often used to improve efficiency in hydraulic systems. 

How does a hydraulic accumulator work?

A hydraulic accumulator is classed as a pressure vessel which holds hydraulic fluid and a compressible gas. Usually, the piston or rubber bladder inside the accumulator is responsible for separating the oil from the gas. The volume of gas in a hydraulic accumulator is precharged to around 80/90% of the minimum system working pressure. Once the system is in operation, the hydraulic pump is responsible for increasing system pressure which forces fluid into the accumulator. This in turn causes the piston or bladder to move which compresses the gas volume because fluid pressure exceeds the precharge pressure.

What gas is used in hydraulic accumulators?

The compressible gas in hydraulic accumulators is typically nitrogen. The gas keeps the hydraulic fluid pressurised.

What are the different types of hydraulic accumulators?

At BSP Hydraulics, we supply accumulators from manufacturers such as Hydro Leduc and Parker. The most common types of hydraulic accumulators are piston, diaphragm and bladder types.

Bladder accumulators

Bladder type accumulators are a popular choice for general-purpose use in medium and high pressure applications with a rubber bladder separating the oil and gas sections. They come in a variety of standard sizes, typically with large ports for quick fluid discharge and to help protect the device from contamination and damage. 

Piston accumulators

Piston accumulators use moveable pistons to separate the two sections. They are often used for heavy-duty applications with high flow rates. The design does make them more sensitive to contamination which can cause damage, but most types of piston accumulators can be repaired by replacing the piston seals.

Diaphragm accumulators

A diaphragm accumulator operates much the same as a bladder accumulator, only using an elastic diaphragm to separate the oil and gas sections instead. This type of accumulator can typically handle higher compression ratios than bladder accumulators because the diaphragm doesn’t distort as much as a rubber bladder. 

There are many advantages of using a hydraulic accumulator but they typically offer the most benefits for hydraulic applications that require high power for short periods of time. They store energy that can be used to supplement pump flow or serve as a backup. Accumulators are also pretty simple to install and require little maintenance.