Hydac FPU Serie Instrucciones De Servicio página 44

7.1 Preparation
NOTICE
Adapter A3H must only be used with the
FPU‑2.
– On bladder accumulators, unscrew valve
protective cap (S) and seal cap (H) and
remove O‑ring (O). Slightly unscrew the
adjusting screw of adapter A3H and screw
adapter A3H on to the accumulator gas
valve.
– On piston, diaphragm and metal bellows
accumulators loosen the allen screw (P) with
the spindle (A).
– Manually screw FPU‑2 cap nut (D) on to
adapter A3H on the bladder accumulator
or on to the accumulator gas valve of
the piston, diaphragm or metal bellows
accumulator.
– Rotate charging device so that the pressure
gauge is in a good position for taking
readings.
7.2 Testing
EN
NOTICE
Before inspection, the charge hose must be
connected gas‑tight with the FPU‑2 and the
pressure-increase system.
– Connect the charging hose to the pressure
increase system with the high‑pressure
connection 9/16‑18UNF.
– Firmly close the unloading valve (B) on
FPU‑2.
– On bladder accumulators, open the gas
valve insert (E) in the accumulator by
rotating the spindle (A) clockwise until the
indicator on the pressure gauges moves.
– On piston, diaphragm or metal bellows
accumulators, open the allen screw (P) in the
accumulator by rotating the spindle (A) anti-
clockwise until the indicator of the pressure
gauge moves.
– The pressure gauge now displays the
pre‑charge pressure (p
accumulator.
The gas‑tight connection between FPU‑2
and the pressure increase system prevents
nitrogen from escaping.
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) in the hydraulic
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7.3 Pressure increase
(charging/recharging)
NOTICE
To recharge a hydro accumulator, always
follow the work steps in section 7.2.
An accumulator is also recharged in steps.
For bladder, piston and diaphragm
accumulators:
Step 1 1 ‑ 2 bar
Step 2 2 ‑ 3 bar
Step 3 desired pre‑charge pressure (p
For metal bellows accumulators:
0.2 bar per second until desired pre‑charge
pressure (p ) is reached. This must not be
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exceeded at any point during the charging
process.
CAUTIOUSLY OPEN the shut‑off valve on the
intensifier. The outlet pressure at the intensifier
is displayed. This corresponds to the display of
the pressure gauge at the FPU‑2
(outlet pressure = current pressure in the
hydraulic accumulator).
NOTICE
We recommend selecting a 10 % higher
accumulator pre‑charge pressure (p
order to compensate for the influence in
temperatures.
This does not apply for metal bellows
accumulators.
– Interrupt the charging process from time
to time by means of the pressure‑increase
system in order to read the achieved pre‑
charge pressure (p ).
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– Repeat this process until the required pre-
charge (p ) pressure is reached. Once the
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temperature has equalised, re-check the pre-
charge pressure (p ) and adjust if necessary.
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