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Precharging Procedure
General Information
14
Accumulators and Accessories
• Prior to commissioning a hydraulic system, any accumulators in the system should have their pre-charge
pressure checked and adjusted.
• The condition of the accumulator is primarily determined by periodic checking of the pre-charge pressure.
• Hydraulic Accumulators are pressure vessels and only qualifi ed personnel should perform maintenance.
• Drain all fl uid completely from accumulator before performing any maintenance.
• DO NOT weld or braze directly on accumulator shell.
• DO NOT use automotive type valve cores as high pressure accumulator gas valves.
• The most accurate pre-charge readings can only be taken when fl uid pressure is at zero.
• Always observe the maximum working pressure and operating temperature ranges.
Pre-charging Bladder Accumulators
A Isolate the accumulator from the system, open the drain valve and make sure hydraulic fl uid pressure is zero.
B Remove gas valve protection cap and valve cap from the accumulator.
C To charge the accumulator, use a charging hose and gauge assembly from the Stauff Charging Kit # STA-CK-1
rated for 250 bar maximum.
D Before using the charging assembly (Figure 1.) make sure that valve A is completely open (counter-clockwise),
and that bleed valve B (Figure 1.) is closed.
E Connect the charging unit to the gas fi ll valve on the accumulator by means of knurled cap D (Figure 1.).
F Fit the gas bottle adaptor (included in Stauff charging kit) to the nitrogen bottle, make sure that the gas valve on
the nitrogen bottle is closed (see Figure 2.) then attach gas hose to the gas bottle adaptor on the nitrogen bottle.
G Connect the other end of gas hose to the Stauff test coupling C (Figure 1.), after taking off its cap.
H Turn valve A (Figure 1.) clockwise to the point where resistance is felt or pressure is registered on the
gauge(only if there is an existing pre-charge).
I SLOWLY open valve on nitrogen bottle (Figure 2.) and allow the gas to fl ow to the accumulator.
J When the pressure in the accumulator is slightly higher than is required, close the valve on the nitrogen bottle.
K Open valve A (Figure 1.) (counter-clockwise) and reduce the pressure in the gas hose and charging assembly to
zero by means of bleed valve B (Figure 1.).
L Remove hose from non-return Stauff test coupling C (Figure 1.) and replace cap.
M Close the bleed valve B (Figure 1.) and wait a few minutes for pressure to stabilise.
N Screw valve A (Figure 1.) clockwise until pressure can be read on gauge. This should be slightly higher than the
required pressure.
O Adjust pressure by means of bleed valve B (Figure 1.), then unscrew valve A (Figure 1.), counterclockwise.
Open valve B (fi gure 1) then remove charging unit.
P Replace gas valve cap and protective cap on accumulator. Accumulator is now ready for use.
B
A
D
C
- Safety pattern gauge.
Figure 1 Figure 2
NOTE: Allow accumulator to rest about 10-15 minutes after gas pre-charging. This will allow gas temperature to adjust
and equalize. Recheck gas pre-charge pressure and adjust if necessary. Check accumulator gas valve for any leaks
with soapy water. Always wear safety glasses.