MTS Series 248 Actuators - Manual (Page 41)

How to Precharge the Static Support
Series 248 Actuator Product Information Operation 41
5. To increase pressure in the static support pressure vessel:
A. Close the locknut.
B. Open the bleed valve on the accumulator charger two turns.
C. Connect the nitrogen supply hose from the pressure regulator output to
the input of the accumulator charger.
D. Open the nitrogen bottle output valve.
E. Check the nitrogen bottle pressure gage to ensure that it contains
sufficient pressure to provide adequate gas volume.
F. Using the regulator output pressure valve, set the reading of the
regulator output pressure gage to the desired level.
G. Slowly open the regulator shut-off valve until gas is heard escaping
from the bleed valve. Allow gas to bleed for approximately 10 seconds
and close the bleed valve fully counterclockwise. Immediately close
the regulator shut-off valve before the pressure reading on the high
pressure gage exceeds the pressure level of the static support pressure
vessel.
6. To reduce pressure in the static support pressure vessel, slowly open the
bleed valve on the accumulator charger until gas begins to escape. When the
pressure reading on the appropriate pressure gage drops to the level desired,
close the bleed valve. Go to Step 7.
7. Open the locknut. Slowly open the regulator shut-off valve until the pressure
indication on the appropriate pressure gage begins to rise. When the
indicated pressure is at the desired level, close the regulator shut-off valve.
To reduce a pressure reading, return to Step 6.
8. Apply high system hydraulic pressure.
9. Monitor the output of the ΔP signal.
10. Increase or decrease the N
2
pressure to obtain a small negative voltage
(between 0.00 and -0.05 V DC). If the system is equipped with a static
support box or static lift panel for N
2
pressure control, see the applicable
documentation for operation of N
2
pressure control.
11. When you have the correct N
2
pressure:
A. Observe the static support N
2
pressure and if it differs substantially
from the calculated value, record the actual pressure for future
reference.
B. Close the locknut. Close the bleed valve.
C. Remove the chuck valve from the pressure vessel valve stem.
D. Replace the protective cover on the valve stem.
E. Open the bleed valve.
F. If used, disconnect the nitrogen supply hose from the pressure
regulator.