MTS Systems SilentFlo 505G2 Series, Manual

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Accessories
76 Series 505G2 SilentFlo™ Hydraulic Power Unit
Changing the precharge pressure
The nitrogen precharge should be within the range of 10.3–12.5 MPa (1500–1800 psi) which is 50–
60% of the output pressure (21 MPa or 3000 psi). Perform one of the following procedures to change
the precharge pressure.
Decreasing pressure
To decrease the precharge pressure:
1. Slowly open the bleed valve on the charging kit until gas begins to escape. When the pressure
reading on the appropriate pressure gage drops to the level required, close the bleed valve.
2. Close the locknut. Open the bleed valve on the accumulator charging kit and remove the
chuck valve from the accumulator.
3. Install the valve stem cap and protective cover.
Increasing pressure
To increase the precharge pressure:
1. Close the locknut on the surge suppressor.
2. Open the bleed valve two turns.
Warning:
Mixing gases can produce unpredictable results.
Do not use another gas to precharge a surge suppressor.
Use only dry nitrogen gas to precharge surge suppressors.
3. Connect the nitrogen supply hose from the supply bottle pressure regulator output to the input
check valve on the charging kit.
4. Open the nitrogen bottle valve. Check the nitrogen bottle pressure gage on the regulator. (The
bottle must contain sufficient pressure to provide an adequate gas volume.)
5. Monitor the regulator output pressure gage and adjust the regulator output pressure valve to
the required level.
Caution:
Avoid rapid and extreme pressure transitions.
Rapid flow rates with pressure differentials of more than 2.1 MPa (300 psi) across the
input check valve can damage the valve seal(s).
Do not allow rapid flow rates. Open the regulator shut-off valve only far enough to
permit a gradual transfer of gas.