MTS Series 505 SilentFlo Hydraulic Power Unit Model 505-180 - Manual (Page 61)

Precharging the Optional Surge Suppressor
Model 505.60 - 505.180 SilentFlo™ HPU Installation 61
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 accumulator.
2. Open the bleed valve two turns.
Precharging with a gas other than dry nitrogen will cause the existing
nitrogen within the surge suppressor to be mixed with the new gas.
Mixing gases can produce unpredictable results.
Use only dry nitrogen gas to precharge the 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.
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.
WARNING
CAUTION