In the fire-resistant oil hydraulic system, the NXQ bladder accumulator realizes energy storage and pressure buffering functions through a bladder pre-filled with nitrogen. Its internal structure consists of a shell, a bladder, a gas valve assembly and an oil channel. As a key energy storage medium, the bladder is prone to aging, bulging or rupture under high-pressure alternating loads for a long time. According to industrial site statistics, about 65% of accumulator failures are caused by bladder failure, and the replacement operation requires the simultaneous completion of nitrogen pressure testing, removal of the old bladder and installation of new components, which places strict requirements on the matching of special tools.

I. Technical characteristics and functional realization of CQJ-40 pressure measurement and nitrogen charging tool

1. Tool parameters and fire-resistant oil system adaptability

CQJ-40 nitrogen charging tool is specially designed for NXQ series high-pressure accumulators, with a rated pressure bearing capacity of 31.5MPa, stainless steel body and carbon steel reinforced structure, compatible with petroleum-based hydraulic oil, water-ethylene glycol and fire-resistant oil and other media. Its interface configuration includes M28×1.5 thread (national standard NXQ model) and 5/8-18UNF (adapted to imported accumulators), and seamless connection with the accumulator gas valve is achieved through quick-change connectors.

2 Integrated operation process of nitrogen filling and pressure measurement

Pre-charge detection: Connect the CQJ-40 pressure gauge module to read the residual nitrogen pressure value of the bladder (the standard pre-charge pressure of the fire-resistant oil system is 9.0±0.5MPa).

Nitrogen supply: When the detection pressure is lower than the threshold, nitrogen is supplemented through a pressure reducing valve or a nitrogen filling vehicle to avoid over-expansion of the bladder due to overpressure.

Pipeline pressure relief: After the operation is completed, the vent valve needs to be opened to empty the residual gas in the hose to prevent high-pressure gas impact during disassembly.

II. Matching design points of special disassembly tools for bladder replacement

The special disassembly tools for NXQ accumulators need to match the following key interfaces:

Valve locking mechanism: Use a reverse thread clamp to prevent the valve assembly from rotating and damaging the sealing surface during disassembly.

Bladder grabbing device: The mechanical arm structure with elastic claws can adapt to the diameter changes of bladders of different volumes.

Fire-resistant oil media are sensitive to impurities, and the tool contact surface must meet the following requirements: surface roughness Ra≤0.8μm to avoid scratching the bladder nitrile rubber layer.

III. Standardized bladder replacement operation process

1 Preparation before operation

System pressure relief: Close the inlet and outlet stop valves of the accumulator block and drain the oil to a dedicated recovery device.

Nitrogen release: Use CQJ-40 to slowly discharge the residual gas in the bladder, and the pressure reduction rate is ≤0.5MPa/s.

2 Key steps for bladder removal

Valve removal: Insert the special wrench into the hexagonal surface of the valve and unscrew the assembly with the torque limiter (set value 35N·m).

Old bladder extraction: Start the vacuum adsorption device to fix the edge of the bladder to avoid pulling and causing debris residue.

Cavity cleaning: Use non-woven cloth to wipe the inner wall of the shell, and prohibit the use of organic solvents to prevent rubber swelling.

3 Installation and testing of new bladder

Preforming treatment: let the new bladder stand for 24 hours at 25℃ to eliminate packaging deformation.

Air tightness test: fill 5MPa nitrogen through CQJ-40, maintain pressure for 30 minutes, and the pressure drop is ≤0.2MPa to pass.

By accurately matching CQJ-40 nitrogen charging tools and special disassembly devices, the maintenance efficiency and reliability of NXQ accumulators can be significantly improved, providing a solid guarantee for the safe operation of fire-resistant fuel systems. It is recommended that users establish a tool usage ledger, regularly calibrate the pressure gauge accuracy, and carry out special training for operators to give full play to the synergy of tools.

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E-mail: sales@yoyik.com
Tel: +86-838-2226655
Whatsapp: +86-13618105229

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