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By Scott Davidson, ManagerSafety News

Hydraulic Accumulator Hazards

A variety of Hydraulic AccumulatorsHydraulics are a key component in many of our operations. It is a valuable and efficient component that enables the equipment in our sawmill, planer mills, logging equipment and aircraft to accomplish an enormous amount of work with very small amounts of physical energy. Just like all other types of machinery, there are specific precautions that must be taken to safely use and maintain hydraulic systems. Ensuring that the equipment is de-energized includes following the appropriate lock-out procedures that have been designed to control the accidental or inadvertent movement of machinery by electricity, pneumatics (air), gravity or hydraulics.

Accumulators are an all to often overlooked potential hazard of a hydraulic system that can be the source of enough energy to move equipment or machinery when it is least expected. An accumulator is a pressurized storage device in a hydraulic circuit that helps maintain a constant pressure of hydraulic oil. It is normally filled with pressurized nitrogen or another inert gas, and will fill to the system pressure when the hydraulics are turned on and operated. When the pump is turned off, the pressurized fluid in the accumulator must be released back to the tank. This is done either by an automatic or manual dump valve. If this valve fails to open and the fluid is not bled back to the tank, then the accumulator remains a pressurized source of energy and a potential hazard.

If the valve were to inadvertently open after the fact, then the fluid would be directed to operate the cylinder or hydraulic motor within the system. This could have devastating results for operators or mechanics. In order to ensure system pressure has been released from an accumulator, the pressure gauge located on the accumulator side of the dump valve must read zero before any work is to be started on the system.

Hydraulic accumulator safety needs to be part of the lockout procedure component of the Job Safety Breakdowns for those using and servicing equipment and machinery that involves hydraulics. It is the responsibility of the supervisors to make aware the hazards of any job site to the workers. Awareness and knowledge of accumulators can eliminate one of those hazards.