HYDAC International SK Serie Instrucciones De Servicio página 45

5. Maintenance of the
accumulator
5.1 Basic maintenance
instructions
In order to ensure long and trouble-free
operation, the following maintenance
procedures must be carried out regularly:
– Test the accumulator pre-charge pressure,
– Check that connections are tight and
leak-free,
– Check the valves and safety equipment for
correct operation,
– Check the fastening elements.
– If the accumulator is operated fast and
continuously, check for oil transfer into the
gas side after a few months.
NOTE
The current regulations for repeat testing in
the country concerned must be observed.
5.2 Pre-charge pressure testing
frequency
It is recommended that the following testing
frequencies be maintained:
– after each installation,
– one week after installation,
– eight weeks after installation.
If no significant gas loss is detected, the test
frequency can be:
– once per year.
NOTE
Continuous operation at high operating
temperatures requires more frequent testing.
5.3 Testing the pre-charge
pressure
The pre-charge pressure can be tested with or
without the FPU charging and testing unit.
On small accumulators, and wherever possible,
the pre-charge pressure should be tested
without the charging and testing unit to avoid
any nitrogen loss during the test.
NOTE
For drawings referred to in the text, see
fold-out page.
The following steps relate to use of the FPU-1
(p = 350 bar). FPU-2 must be used for
0, max
higher pressures. For more information, see:
"Instruction Manual for Charging and Testing
Unit FPU", no. 3.501.BA
Testing re-chargeable piston
accumulators with the FPU-1 charging
and testing unit
The following steps should be followed for
testing and charging using the FPU-1 charging
and testing unit:
– Piston accumulators, as well as all lines
connected on the fluid-side of the
accumulator, must be released of pressure
and must remain open.
– Unscrew the protection cap (230) from the
piston accumulator.
– Slightly loosen the allen screw (210) by the
piston accumulator with allen key SW 6,
DIN 911 (roughly 1/2 a rotation).
To avoid leakages on the gas side, the seal
ring (200) must be lubricated with a suitable
fluid before re-assembly.
– Screw the FPU-1 onto the gas charging
connection of the piston accumulator
(M28 x 1.5) by hand.
– Close the unloading valve (B).
The following step is only necessary if the
accumulator must also be charged.
– Connect the nitrogen bottle (N2) with
pressure reducer (D) and adapter (G), if
required, with charging hose (F) to the
FPU-1 at the non-return valve (N).
Testing
– Turn the spindle (H) anti-clockwise to open
the gas valve. Once the pressure gauge (M)
indicator begins to move, turn the spindle
one more full rotation.
– Check the actual pre-charge pressure on the
pressure gauge (M).
GB
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