HYDAC SK 600 - Manual (Page 3)

Maintenance
INNOVATIVE FLUID POWER 51
PN#02068195 / 04.13 / ACU1102-1326
6.2. Charging Procedure with the Charging
and Gauging Unit
Using the charging and gauging units, hydraulic accumulators can
be charged with nitrogen or tested to the precharge pressure P
0
.
First, isolate the piston accumulator from the hydraulic system by
closing the shut off valve A and discharge it on the fluid side. Then
remove the valve seal cap of the piston accumulator.
When using accumulators with gas valves version 1 the gas valve
insert must first be unscrewed slightly (approx. 1/2 turn) using a 6mm
allen wrench.
The T-handle of the FPU-1 must not be used for this. Now the
charging and gauging unit can be connected.
When using accumulators with gas valve version 4, the valve seal
cap must first be unscrewed. Only then can the charging and
gauging unit and the nitrogen bottle be connected in accordance
with the operating instructions (with adapter A3) . Ensure that the
pressure release valve of the charging and gauging unit is closed.
Turn the spindle in a counter-clockwise direction to unscrew the
internal hex screw of the gas valve. Then slowly open the valve of the
nitrogen bottle so that the nitrogen is released into the accumulator.
Wait until approximately 1 bar precharge pressure has been reached
and the piston is at the fluid side before opening the shut off valve of
the nitrogen bottle further to enable faster charging.
Gas Valve Version 1 Gas Valve Version 4
valve
protection
cap
(where applicable)
Valve
seal cap
O-ring
Allen Wrench 6 mm
(to be used to crack open M8 SHCS.
T handle on FPK Charging is not robust
enough to overcome recommended torque)
Valve protection cap
(where applicable)
O-ring (where applicable)
Socket Head
Cap Screw (M8)
Seal ring
Interrupt the charging procedure from time to time and check
the precharge pressure reached. When the required precharge
pressure has been reached, close the shut-off valve of the nitrogen
bottle. Wait for approx. five minutes until temperature equalization
is reached (a longer period must be allowed for larger systems quantities) ,
then recheck the precharge pressure and adjust if necessary. If the
pressure is too high, it can be lowered via the pressure release valve
of the charging and gauging unit.
Turn the spindle clockwise to securely tighten the internal hex screw.
Then discharge the charging and gauging unit via the pressure
release valve and remove it by loosening the cap nuts. On piston
accumulators with gas valve version 1, the internal hex screw must
be tightened to a torque rating of 20 Nm and with version 4 the valve
seal cap must be tightened to a torque rating of 30 Nm. Finally check
for leaks on the accumulator gas valve using a leak detector spray.
Screw on valve protection cap.
Further details can be found in the operating instructions for part
number 02068202.
6.3. Pressure Testing
For piston accumulators with a permissible operating pressure p
greater than 1 bar and a pressure capacity p*V > 1000, for non-
corrosive fluids, a pressure test must be carried out by an approval
authority every 10 years, otherwise every 5 years.
An internal inspection must be carried out every five years and an
external inspection every two years.
7. Storage and Preservation
If the period of storage until commissioning is no longer than three
months, it is sufficient for the precharged accumulator to be stored
in a cool, dry place, protected from direct sunlight, providing that
the inside of the accumulator has first been coated with the intended
hydraulic fluid. The accumulator can be stored in any position. To
prevent contamination from entering the accumulator, ensure that
the hydraulic connection is plugged.
If the accumulator is to be stored for longer than three months,
check the required precharge pressure of the accumulator before
commissioning.
If the accumulator has not been precharged, it must be plugged
on the gas side and conserved with the intended operating fluid or
another suitable conservation fluid.