HYDAC International SB330 Instrucciones De Servicio página 34

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 future
test intervals can be carried out once per year.
once per year.
NOTICE
Continuous operation at high operating
temperatures requires more frequent testing.
The nominal values of the pre-charge
pressure (p ) are based on a charging
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temperature of 20 °C.
5.3 Testing the pre-charge
pressure
EN
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.
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Testing without the charging and
testing unit FPU-1
If the 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
also be checked via the fluid side.
– Isolate the hydraulically-charged bladder
accumulator with shut-off valve  from the
system.
– Use pressure relief valve  to slowly drain
the bladder 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 ) of the bladder accumulator.
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– If the indicated pre-charge pressure (p
differs from the nominal pressure, it must be
corrected as described above, see section
4.3.
Testing with the charging and testing
unit FPU-1
To test and charge using the charging and
testing unit FPU-1 see section 4.3.
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