MTS Hydraulic Service Manifold Model 293-12B - Manual (Page 50)

Checking the Accumulators
The accumulators have a pressure charge of compressed gas. The accumulator’s correct precharge
pressures are recorded on their labels. The precharge pressure should be checked once a month.
Warning :
Do not charge the accumulators with gases other than pure (commercial grade, dry) nitrogen
gas.
Using unacceptable gasses can cause personal injury, damage to equipment, or both.
Refer to the accumulator manual for information about charging the accumulator.
The recommended accumulator precharge levels for an HPU output of 21 MPa (3000 psi) are as follows:
Precharge Accumulator
7 MPa (1000 psi) 3 Main pressure
0.35 MPa (50 psi) 4 Return
7 MPa (1000 psi) Pilot pressure
1.4 MPa (200 psi) Slow turn-on
Record both the pressure and the room temperature in a log book. Use these readings as a basis for
changing the interval between pressure checks. Initially, check the precharge after two weeks or 100
operating hours:
• If there is a change of ±1.4 MPa (±200 psi) or more in the pressure line accumulator, check the precharge
every week or 50 operating hours.
• If there is a change of less than ±1.4 MPa (±200 psi) in the pressure line accumulator, check the
precharge every four weeks or 200 operating hours.
• If there is a ±50% or more change in the return, pilot pressure, or slow turn-on accumulators, check
the precharge every week or 50 operating hours.
• If there is a change of less than ±50% in the return, pilot pressure, or slow turn-on accumulators, check
the precharge every four weeks or 200 operating hours.
See the Series 111 Accumulator Product Information manual (MTS part number 011-553-304) for
maintenance procedures.
3 May be varied according to system performance.
4 For optimum performance, set the precharge within this range as close as possible to the low-pressure
setting (2.8 MPa; 400 psi minimum).
50 | Series 293 Hydraulic Service Manifold Product Information
Maintenance