Maintenance Instructions
for
Hydraulic Accumulators

Bookmarks

• Preparation of accumulator for maintenance
  • ..with safety block
  • ..with bleed facility
• Instructions for dissembling hydraulic accumulators
  • ..removal of precharge
  • ..removal of bladder
    • ..preparing the gas end
    • ..preparing the fluid end
• Cleaning and inspection
• Re-assembly of bladder accumulator

Diagram of Accumulator Parts

Preparation of Accumulator for Maintenance

Isolation & Drain

(a) WITH SAFETY BLOCK

Close Isolating Valve. ( 1 )

Open the Manual Relief/Drain Valve ( 2 ) until Pressure Gauge ( 3 ) registers zero.

Remove the Accumulator from Safety Block.

(b) WITH BLEED FACILITY

Isolate the Accumulator from the System.

Open Bleed facility, draining system fluid into a suitable receptacle, until all fluid and pressure have been removed.

Remove the Accumulator from System Pipework.

THE ACCUMULATOR CAN ONLY BE REMOVED FROM THE SYSTEM PIPEWORK ONCE THE HYDRAULIC PRESSURE HAS BEEN REMOVED FROM THE ACCUMULATOR

Instructions for Disassembling Hydraulic Accumulators

Removal of Precharge

Remove Protective Cap (Item D4 +) from the Bladder

Stem by unscrewing anti-clockwise.

Remove Sealing Cap from the Gas Valve Assembly (Item D2 +).

Connect Charging Set to the Gas Valve Assembly

Release all the gas pressure by opening the Vent Valve. (1)

Disconnect the Charging Set from the Accumulator.

Removal of Bladder

Preparing the Gas End

Unscrew the Gas Valve Assembly (Item D2 +) from the Bladder Stem by turning anti-clockwise.

Remove the Locknut (2) and Nameplate (3) from the Bladder Stem by turning the Locknut anti-clockwise.

Preparing the Fluid End

Remove the Bleed Adaptor (Item B8 +) by unscrewing anti-clockwise.

Unscrew the Locking Ring (Item B7 +) 2 or 3 turns anti-clockwise and then push the Fluid Port Body (Item B1 +) into the Accumulator Shell to check that the Bladder precharge has been fully released.

Remove the Locking Ring (Item B7 +) and the Flanged Washer (Item B6 +)

Push the Fluid Port Assembly (Item B1 +) into the Accumulator Shell.

Remove the 'O'Ring (Item E2 +) and the Backup Ring (Item E4 +)

Slide the Anti-Extrusion Ring (Item E1 +) off the Fluid Port Assembly

Fold the Anti-Extrusion Ring (Item E1 +) until removal from the Accumulator Shell is possible.

Remove the Fluid Port Assembly (Item B1 +) from the Accumulator Shell.

Squeeze the Bladder (Item D1 +) by hand to deflate as much as possible, then slowly remove through the Fluid Port opening in the Accumulator Shell.

Cleaning and Inspection

Clean all Metallic Components with an Organic Solvent.

Inspect the condition of all components within the Fluid Port. (Item B +)

Check the Fluid Port Poppet Valve to ensure free movement.

Inspect the Bladder (Item D1 +) for any visible signs of damage.

(Cracking or Surface Abrasion etc.)

Inspect the Shell (Item C1 +), both Inside and Outside for signs of corrosion.

Replace any parts found or considered to be defective.

Replace the following parts irrespective of condition:

1) Anti-Extrusion Ring (Item E1 +)

2) 'O'Ring (Item E2 +)

3) Back Up Ring (Item E4 +)

4) 'O'Ring (Item D5 +)

PLEASE NOTE:

IT IS POLICY OF FAWCETT CHRISTIE HYDRAULICS TO REPLCAE ALL RUBBER COMPONENTS (INCLUDING THE BLADDER) WHEN  REPAIRING OR RE-CERTIFYING BLADDER ACCUMULATORS

Re-assembly of Bladder Accumulator

Expel all air from the Bladder (Item D1 +) by rolling up from the opposite end to the Stem.

Whilst the Bladder is rolled up, fit the Stem 'O' Ring (Item D5 +) and Gas Valve Assembly (Item D2 +).

Unroll the Bladder (Item D1 +) and lubricate both the Bladder and the Inside of the Shell (Item C1 +) with System Fluid.

Attach Pull Rod to Gas Valve Assembly. (Item D2+)

Feed Pull Rod through Fluid End Opening and out of Gas End Opening.

Begin pulling Bladder into the Shell using the Pull Rod. Do not twist the Bladder during this operation.

Pull the Bladder Stem through the Gas End Opening and fit the Nameplate and Locknut (Item D3 +) by turning clockwise.

Insert the Fluid Port Assembly (Item B +) and Anti-Extrusion Ring (Item E1 +) into the Shell Fluid End Opening.

Slide the Anti-Extrusion Ring over the Fluid Port Body and then pull the Fluid Port through the Shell Fluid End Opening.

Remove Pull Rod from the Gas Valve. (Item D2 +)

Fit Charging Set onto Gas Valve (Item D2 +) and Inflate the Bladder with a low  Pre-Charge of 2 Bar to seat the Fluid Port Assembly and Anti-Extrusion Ring.

Using a Rubber or Nylon Hammer tap the Fluid Port Assembly at various angles to ensure that the Fluid Port is correctly seated within the shell.

Fit 'O' Ring (Item E2 +) and PTFE Back Up Ring (Item E4 +) onto the Fluid Port Assembly Body (Item B +) and position inside the gap left between the Shell and the Fluid Port Body.

Slide the Flanged Washer (Item B6 +) over the Fluid Port Body until it comes into contact with the PTFE Back Up Ring. (Item E4 +)

Fit Locking ring (Item B7 +) onto Fluid Port Body and screw clockwise until hand tight and then tighten with the correct spanner.

Replace Bleed Valve and Bleed Adaptor (Items B8 & B9 +) into Fluid port Assembly (Item B +) by screwing clockwise and tighten with spanner.

Precharge Bladder to predetermined pressure using dry Nitrogen Gas only.

Remove the Charging Set and refit the Dust Cap to the Gas Valve. (Item D2 +)

Check Locking Ring (Item B7 +) and Locknut (Item D3 +) for tightness.

The Re-Assembly is now complete and the Accumulator is ready to be returned to service.