Fluids are practically incompressible and cannot therefore store pressure energy. The compressibility of a gas (nitrogen) is utilized in hydro-pnuematic accumulators for storing fluids. HYDAC bladder accumulators are designed on this principle, using nitrogen as the compressible medium.

The bladder accumulator consists of a fluid section and a gas section, with the bladder acting as a gas-proof screen. The fluid around the bladder is connected with the hydraulic circuit, so that the bladder accumulator draws in fluid when the pressure increases thus compressing the gas. When the pressure drops, the compressed gas expands and forces the stored fluid into the circuit.

Bladder Materials

Not all fluids are compatible with every elastomer at all temperatures. HYDAC offers the foilowing choice of elastomers:

• NBR (standard nitrile)
• LT-NBR (low temperature nitrile)
• ECO (epichlorohydrin)
• IIR (butyl)
• EPR (ehtylene propylene)
• FPM (fluorelastomer)

Construction

HYDAC bladder accumulators consist of a welded or forged pressure vessel (shell), a bladder and ports for gas and fluid inlet. The gas and fluid sides are separated by the bladder.

Corrosion Protection
HYDAC offers internal and/or external protective coatings. If this is insufficient, stainless steel is also available.