Operating Data - HYDAC International FPU Instrucciones De Servicio

5.1 Pre-charge pressures
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When working with the FPU, take into
account the influence of the charging temper-
ature on the pre-charge pressure. For values,
see fold-out page: Correction of the pre-
charge pressure [I-1]
T [°C] = reference temperature
0
The reference temperature is the temperature
for which HYDAC specifies/calculates the
corresponding reference pre-charge pressure
(p ). It is generally 20 °C (room temperature).
0
T [°C] = accumulator temperature
The accumulator temperature is the surface
temperature measured on the gas side of the
hydraulic accumulator.
p [bar] = reference pre-charge pressure
0
The reference pre-charge pressure is the pre-
charge pressure of the hydraulic accumulator
at 20 °C. It is specified on the hydraulic accu-
mulator (adhesive label on the accumulator
shell, stamped on the accumulator shell,
engraved on the name plate) – see hydraulic
accumulator operating instructions.
Incremental recharging
The hydraulic accumulator must be
recharged in incremental steps.
● SB, SK, SBO:
1. Intermediate step: 1–2 bar
2. Intermediate step: 2–3 bar
3. Final step: desired pre-charge pressure
● SM:
0.2 bar per second until desired pre-
charge pressure is reached. The desired
pre-charge pressure must not be
exceeded at any point.
Limits in accordance with the overview
brochure must be observed – see other
relevant documents: 3.000 [Sec. 1]

5.2 Operating data

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Operating temperature FPU:
-10 °C to +80 °C
Operating temperature pressure-reducing
valve:
-20 °C to +60 °C
Operating pressure:
FPU-1: max. 350 bar
FPU-2: max. 800 bar
INT 3.501.BA14/03.23
6. Working with the FPU-1
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The following work relates to checking and
setting the pre-charge pressure in the
hydraulic accumulator.
6.1 Preparation
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Adapter A3 [III-1] must only be used with
the FPU‑1.
1. Check FPU for damage. A damaged FPU
must never be put into operation.
2. SB: Unscrew protective cap S [III-3] and
seal cap H [III-3] and remove O-ring O
[III-3]. Slightly unscrew the adjusting screw
of adapter A3 [III-1] and screw adapter A3
[III-1] onto the accumulator gas valve.
SK, SBO, SM: Loosen the allen screw P
[III-4] with an allen key (AF width 6, DIN
ISO 2936) WZ2 [III-4] by approx. 1/2 a
turn.
3. Screw on cap nut D [II-1] of the FPU by
hand.
SB: onto the adapter A3 [III-1]
SK, SBO, SM: onto the accumulator gas
valve
4. Rotate FPU so that the pressure gauge is in
a good position for taking readings.
6.2 Testing
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1. Close the release valve B [II-1] on the
FPU.
2. SB: Rotate the spindle A [II-1] clockwise to
open the gas valve insert E [III-3] in the
hydraulic accumulator until the indicator on
the pressure gauges moves.
SK, SBO, SM: Rotate the spindle A
[II-1] counterclockwise to open the allen
screw P [III-4] until the indicator of the
pressure gauge moves.
3. The pressure gauge now displays the pre-
charge pressure in the hydraulic accumu-
lator. The check valve C [II-1] prevents
nitrogen from escaping.
6.3 Pressure increase (charging/
recharging)
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If you have not yet done so, prepare the
hydraulic accumulator and check pre-charge
pressure – see Preparation [Sec. 6.1] and
Testing [Sec. 6.2].
Charging, and in particular recharging,
hydraulic accumulators must be done incre-
mentally – see Incremental recharging
[Sec. 5.1].
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EN