Pressure accumulator failure generally occurs when the gas chamber section deteriorates, allowing pre-charge gases to infiltrate the fluid portion. This results in insufficient back-pressure for the system to function optimally.
Accumulator failure is frequently caused by:
- Foreign matter in the fluid, leading to undue wear on o-rings or the bladder.
- Mismatch between fluid type and seal material. It is essential that the material used is compatible with the fluid and temperature requirements of the system. Changing fluid types without understanding their composition can accelerate seal degradation and increase the accumulator’s cycle time.
- System design issues. If the accumulator is incorrectly sized or has the wrong back pressure, the bladder or piston o-rings may need to cycle more often than they should, speeding up seal wear and leading to early failure.
Bladder accumulators are generally more prone to failure than piston types, often due to the flexing of the bladder diaphragm. Over time, this can alter the material’s molecular structure, creating weak points.
Signs of accumulator failure include:
- The hydraulic pump runs longer to maintain system pressure. When the pump switches off and the system relies on the accumulator’s reserve pressure, the pressure drops below the threshold, causing the pump to reactivate early and potentially fail prematurely.
- The hydraulic system fails to reach the desired spike pressure. This may suggest that the nitrogen providing the system’s back pressure has leaked past the o-ring or bladder, leading to premature pump or relay failure.
Failure to identify and replace a faulty accumulator can result in excessive wear on the pump section and premature failure of pump section components.
The accumulator should have sufficient capacity to enable multiple system activations before needing to be re-primed, allowing the pump section and motor adequate rest periods.
Testing the accumulator requires a specific test procedure to accurately determine its backpressure.
