HYDAC International SK Serie Notice D'utilisation page 34

5.3 Testing the pre-charge
pressure
The pre-charge pressure (p
with or without the FPU charging and testing
unit.
On small hydraulic accumulators, and wherever
possible, the pre-charge pressure (p
be tested without the charging and testing unit
to avoid any nitrogen loss during the test.
NOTICE
For drawings referred to in the text, see fold-
out page.
Testing without the FPU-1 charging
and testing unit
If the hydraulic accumulator is set up as per
the fold-out page or by using the safety and
shut-off block (SAF or SAB), the pre-charge
pressure (p ) can also be checked via the fluid
0
side.
EN – Isolate hydraulically charged piston
accumulator with shut-off valve  from the
system.
– Use pressure relief spindle  to slowly drain
the piston accumulator on the fluid side.
– Watch the pressure gauge .
– The pressure will initially fall slowly. It will
drop suddenly only after the hydraulic
accumulator has drained completely. This
pressure is the same as the pre-charge
pressure (p
0
– If the indicated pre-charge pressure (p
differs from the nominal pressure, it must be
corrected where possible, see section 4.3.
Testing with the FPU-1 charging and
testing unit
To test and charge using the FPU-1 charging
and testing unit, see section 4.3.
34
) can be tested
0
0
) of the piston accumulator.
5.4 Checking for oil leakage on
the gas side
When the hydraulic accumulator is operated
fast and continuously, oil can leak through the
piston seals into the gas side.
This can be detected as follows:
– A loss of power of the machine or system
) should
– A higher gas pre-charge pressure than
before
– Escape of oil or oil mist when loosening the
locking screw (210)
NOTICE
The oil must only be removed by
appropriately qualified persons.
6. Service life
Like all pressure vessels, piston accumulators
have a finite service life. The service life is
dependent on the amplitude of pressure
fluctuations and on the number of load
reversals.
The permitted load reversals are specified
in the documentation. The authorised
representative can use this data to determine
the operating life of the piston accumulator
(housing strength) depending on the operating
conditions of the hydraulic system.
)
0