HYDAC International FPU-1 Instrucciones De Servicio página 33

5. Working with the FPU-1
NOTICE
Safety precautions according to section 4.2
must be observed.
The following works refer to the testing and
setting of the accumulator pre‑charge pressure
(p ) with the FPU‑1.
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5.1 Preparation
NOTICE
Adapter A3 must only be used with the FPU1.
– On bladder accumulators, unscrew
protection cap (S) and seal cap (H) and
remove O‑ring (O). Slightly unscrew the
adjusting screw of adapter A3 and screw
adapter A3 on to the accumulator gas valve.
– On piston and membrane accumulators,
loosen the allen screw (P) with an allen key
SW6, DIN ISO 2936 by approx. 1/2 a turn.
– Manually screw FPU‑1 cap nut (D) on to
adapter A3 on the bladder accumulator or on
to the accumulator gas valve of the piston or
diaphragm accumulators.
– Rotate charging device so that the pressure
gauge is in a good position for taking
readings.
5.2 Testing
– Firmly close the release valve (B) on FPU‑1.
– On bladder accumulators, open the gas
valve insert (E) in the hydraulic accumulator
by rotating the spindle (A) clockwise until
the indicator on the pressure gauges moves.
– On piston and diaphragm accumulators,
open the allen screw (P) in the hydraulic
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 unloading valve (C) prevents nitrogen
from escaping.
) in the hydraulic
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5.3 Pressure increase
(charging/initial charging)
NOTICE
To recharge a hydro accumulator, always
follow the work steps in section 5.2.
An accumulator is also recharged in steps:
1. Step 1 ‑ 2 bar
2. Step 2 ‑ 3 bar
3. Step desired pre‑charge pressure (p
– Connect the pressure‑reducing valve with
the nitrogen bottle.
For nitrogen bottles from other countries, use
a G adapter (see fold‑out page, Drawing 5 I).
– Connect the charging hose to the pressure
reducing valve with the cap nut G1 (GM1,
GW1) on the charging hose.
– Connect the cap nut (M) of the charging
hose to the check valve (C) of the FPU‑1.
– Close the pressure reducing valve.
– Open the shut‑off valve on the nitrogen
bottle. The pressure gauge at the pressure
reducing valve shows the starting pressure
(starting pressure = nitrogen bottle pressure).
NOTICE
We recommend selecting a 10 % higher
accumulator pre‑charge (p
compensate for the influence in temperature.
– SLOWLY ADJUST the back pressure at the
pressure reducing valve. The pressure
gauge at the FPU‑1 also indicates the back
pressure (back pressure = desired pre‑charge
pressure (p )).
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– The accumulator is charged to the selected
pre‑charge pressure (p
– Once the temperature has equalised,
re‑check the pre‑charge pressure (p
adjust if necessary.
5.4 Pressure reduction
(pressure relieve)
– The release valve (B) is opened slowly.
The nitrogen is released into the
atmosphere.
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