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Support / Pre-Charging
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For correct operation and performance of all accumulators on any system it is essential that the accumulator nitrogen precharge is set correctly for the system . QHP offer this facility as part of our sales support package, however in many applications it is not possible to precharge accumulators until they are in situ. Under these circumstances the following procedure should be carried out.
Pre-charging Instructions:
Note: Only Oxygen Free Nitrogen is to be used for this purpose.
Remove protective cap and sealing cap from gas valve assembly.
Ensure that handwheel is fully retracted (Anti-Clockwise) and that bleed screw is open.
Connect charging hose to charging assembly and Nitrogen supply (Nē Cylinder).
Fit charging assembly (QCS 33-1400/-) to gas valve (do not over tighten).
Open Nitrogen supply gently and allow gas in a controlled manner (low flow) to pass through vent in charging set. Close vent valve and this will let gas enter the accumulator until a pressure slightly in excess of final pressure is obtained. Close Nitrogen supply. (Note: Excess fluid and air will be expelled through the fluid port).
Allow Nitrogen pressure to stabilise (approx 5 minutes).
Follow Pre-Charge Check Procedure.
Pre-Charge Checks
For correct operation and performance of all accumulators on any system it is essential that the accumulator nitrogen precharge is set correctly for the system. QHP can provide any technical advise or assitance in advising the best precharge for each application however it is imperative that the customer /end user checks and maintains this precharge throughout the units working life. The following basic stem should be undertaken when checking the accumulator precharge.
Procedure
Isolate the accumulator from the system and reduce fluid pressure to zero.
Remove the protective cap and sealing cap from gas valve assembly.
Fit charging assembly (QCS 33-1400) having ensured that handwheel is fully retracted (Anti-Clockwise) and bleed screw is closed.
Rotate (Clockwise) handwheel until a pressure is registered.
If the pressure is high it can be reduced by opening the bleed screw until the correct pressure is registered on the gauge. If the pressure is low please refer to pre-charging procedure. If the pressure is correct remove the charging assembly as follows:
Retract Handwheel (Anti-Clockwise).
Open bleed screw.
Remove charging assembly.
Replace sealing and protective caps.
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