DGUV Information 209-071 - Safe maintenance of hydraulic systems (DGUV Informati...

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Abschnitt 4.7, 4.7 Accumulator systems
Abschnitt 4.7
Safe maintenance of hydraulic systems (DGUV Information 209-071)
Titel: Safe maintenance of hydraulic systems (DGUV Information 209-071)
Normgeber: Bund
Amtliche Abkürzung: DGUV Information 209-071
Gliederungs-Nr.: [keine Angabe]
Normtyp: Satzung

Abschnitt 4.7 – 4.7 Accumulator systems

Accumulators are devices the manufacturer has to meet special safety provisions for. Furthermore, the operator of work equipment has to observe the provisions for the tests in accordance with the Ordinance on Industrial Safety and Health (see section 7).

As maintaining and filling accumulators with gas, measuring pressures, and testing upon commissioning require special knowledge, work on accumulator systems must only be conducted by especially trained maintenance technicians or by the manufacturer. It is imperative to observe the provisions of the manufacturer in the operating instructions.

Before working on the accumulator the pressure in the accumulator has to be reduced, along with the pressure of the system hydraulics. This is implemented either automatically or via a manual pressure reduction feature at the accumulator safety block. A pressure indicator, e. g. pressure gauge, has to be used to check the efficiency of the depressurization procedure. It has to be observed that the accumulator may be under high pressure on the gas side. It may be required to reduce this pressure as well. Before the accumulator is removed from the system, both, the fluid and the gas side must be fully unloaded.

New or repaired accumulators on oil-hydraulic systems may be delivered precharged with nitrogen (at low pressure of, e. g.. 2 bar) on the gas side in order to protect the accumulator bladder against in-transit damage.

Before commissioning, these accumulators have to be charged to the charging pressure specified in the hydraulic circuit diagram using nitrogen.

Note
Due to risk of explosion, in no case may oxygen or air be used to fill accumulators.

When replacing the gas-side filling valve in the accumulator, valves specified by the manufacturer (only genuine spare parts) may be used only.

Fig. 21 Warning note on accumulator system

It is im perative to observe the notices in the operating instructions for filling the accumulator with nitrogen. The accumulator filling device comprises

  • pressure reducing valve, connection line from the gas bottle/central gas supply to the accumulator with corresponding connections,

  • accumulator-side port with pressure gauge,

  • appropriate tools.

Neither welding nor soldering works and no mechanic processing may be implemented on accumulators.

On the basis of the special safety-relevance, accumulators have to be checked for mechanical damage.

After installation of the accumulator, the accumulator safety block has to be attached correctly and the accumulator (see figure 22) and possibly existing protective guards against external damage have to be re-installed properly.