Pressure Accumulator Failure

Typical accumulator breakdown occurs when gas chamber section has been compromised.

This causes pre-charge gasses to escape into fluid section and eventually fail to provide enough accumulator back-pressure for system to function properly.

The common causes of accumulator failure are as follows:

  1. Foreign matter in fluid. This will lead to excessive abrasion on o-rings and/or bladder
  2. Incompatible fluid and seal material. The material used must meet the fluid and temperature requirements of system. Without knowing material it is not recommended to change fluid types other than what was suggested by manufacturer. Doing so could speed the deterioration of accumulator seals and increased cycle time.
  3. System Design. If the accumulator is not sized correctly or the incorrect back pressure is added to the system the bladder or piston o-rings will be put in a position where they are required to run a full travel cycle too frequently. This will will cause seals abrasion to happen faster than normal and lead to premature failure.

In general, bladder accumulators tend to have a higher failure rate than piston types. In a lot of cases this is due to bladder diaphragm flexing. Over time molecular structure of material changes and creates a weak-point. 

Typical symptoms of accumulator failure are:

  1. The hydraulic pump stays on longer to maintain system pressure. When pump shuts off and system tries to utilize accumulator reserve pressure there is sudden drop to bellow pressure threshold and pump will be reactivated prematurely to increase pressure. This will result in premature failure of the pump. 
  2. The hydraulic system cannot reach the desired spike pressure. In this instance the nitrogen providing the back pressure in the system has likely leaked past the o-ring or bladder. The hydraulic pump will continue to turn on resulting in premature failure of the pump or failure of the relay.

Failure to diagnose and remove a bad accumulator will lead to abuse of pump section and premature failure of pump section components.

The accumulator should have enough capacity to provide multiple system activation's before it needs to be re-primed. This allows pump section and motor to have a good resting period before it is called upon to re-pressurize system.

Testing of accumulator should be done by specific test procedure to determine accumulator backpressure. 

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