MTS Series 505 SilentFlo Hydraulic Power Unit Model 505-30 - Manual (Page 35)

Precharging the Surge Suppressor Accumulator
Model 505.20 - 505.30 SilentFlo™ HPU Installation 35
B. If the output pressure gage shows no pressure, press the Stop button to
shut down the unit (do not run more than 10 seconds in the wrong
direction). Have a qualified electrician make a change in the electrical
phase to the motor.
6. Check for unusual noises or leaks. If a problem is found, press the Stop
button. You must correct the problem before you continue.
7. Turn the High/Low/Start switch to the High position.
8. Verify the correct output pressure, as shown on the pressure gage.
A. Adjust the pressure if necessary.
B. If the pressure is adjusted, the auto-cooling function may need to be
adjusted.
9. Press the Stop button to shut down the unit.
Precharging the Surge Suppressor Accumulator
The surge suppressor smooths out the ripple caused by the pulsing action of the
pump as it pressurizes the hydraulic fluid. The surge suppressor is a cylinder that
has an outer sleeve that is pressurized with nitrogen. The gas pressurized sleeve
dampens the pressure pulses.
The surge suppressor is mounted to the output of the hydraulic pump inside the
reservoir.
It is normal for a small amount of surge suppressor precharge loss to occur during
operation. Because of this gradual reduction in precharge pressure, the pressure
should be checked and recharged (if necessary) at regular intervals.
Determining a
pressure check
interval
The precharge pressure checking intervals of your surge suppressor depends on
how your system is used. Vigorous use causes more rapid pressure loss and thus
requires checking and recharging more often.
Initially, check the surge suppressor precharge pressure every month or 160
operating hours. If the precharge pressure changes more than 1.4 MPa (200 psi)
during this time period, recharge the surge suppressor and check the pressure
twice as often in the future. If the precharge pressure changes less than 1.4 MPa
(200 psi), check the pressure half as often.
When you have established a regular interval for checking the precharge
pressure, note the amount of pressure loss that occurs each time the pressure is
checked. An increase in pressure loss during the period between checks might
indicate that the surge suppressor seals or bladder require replacement.
Checking the
precharge pressure
The nitrogen precharge should be about 50–60% of the output pressure. To check
the accumulator precharge:
1. Turn off the HPU and ensure that the hydraulic pressure is zero before
proceeding.
2. Connect the charging kit chuck valve to the valve stem on the accumulator,
or to the remote charge valve on the reservoir top, if supplied.