Hydac FPU Serie Instrucciones De Servicio página 43

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.
– 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.
6.4 Pressure reduction
(downward adjustment)
– The release valve (B) is opened slowly.
The nitrogen is released into the
atmosphere.
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6.5 Finishing
– On bladder accumulators, close the gas
valve insert (E) in the hydraulic accumulator
by rotating the spindle (A) anti-clockwise.
– On piston, diaphragm or metal bellows
accumulators, close the allen screw (P) in
the hydraulic accumulator by rotating the
spindle (A) clockwise.
– Close the nitrogen bottle.
– Reduce pressure in the pressure reducing
valve, charging hose and FPU‑1 via the
release valve (B) of the FPU‑1.
– Remove the charging hose from the FPU‑1.
– Loosen the cap nut (D) and remove the
FPU‑1 from the accumulator.
– On bladder accumulators, unscrew adapter
A3 and insert the O‑ring (O) again. Check
the tightness of the gas valve using leak
detection spray.
Screw and firmly tighten the seal cap (H)
onto the accumulator gas valve (30 Nm).
Manually screw on protective cap (S).
– On piston, diaphragm or metal bellows
accumulators, firmly tighten (20 Nm) the
screw plug (P) with an allen key AF width 6,
DIN ISO 2936. Check the screw plug (P) for
leaks using leak detector spray.
Screw and firmly tighten (20 Nm) the seal
cap (S) onto the screw plug (P).
7. Working with the FPU-2
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‑2.
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