What is the maintenance interval for superimposed hydraulic control check valves?

The maintenance cycle and content of the superimposed hydraulic control check valve are as follows:

Daily/weekly maintenance:

Appearance inspection: Check whether the valve body has cracks, deformation or leakage, and whether the connection parts are tight.

Temperature monitoring: The valve body temperature should be ≤70°C to avoid abnormal heating.

Pressure monitoring: record forward pressure drop and control pressure data, and observe pressure stability.

Sound check: Confirm that there are no abnormal sounds or vibrations to prevent the valve core from getting stuck or sealing failure.

Maintenance every 3 months:

Leak check: Check whether there is leakage at each connection part and whether the tightening torque meets the standards (for example, Z2S series is 15–20N·m).

Opening/unlocking pressure test: Verify whether the opening and unlocking pressure of the hydraulically controlled check valve is within the specified range.

External cleaning: remove oil and dust on the surface of the valve body and keep it clean.

Filter inspection: Check whether the system filter is blocked and clean or replace the filter element if necessary.

Maintenance every 6–12 months:

Disassembly, inspection and cleaning: Disassemble the valve core, valve seat and control piston, clean them with clean kerosene or hydraulic oil to remove attached colloid and metal particles.

Seal replacement: Replace wearing parts such as O-rings and valve seat seals. In conventional hydraulic systems, it is recommended that O-rings be replaced every 6 months or every 1,000 hours of operation; if the medium temperature exceeds 80°C or contains corrosive components, the replacement cycle is shortened to 3 months.

Spring detection: measure the free length of the spring. If it shortens by more than 5%, replace it; press the spring and release it. If it cannot reset quickly or plastic deformation occurs, it also needs to be replaced.

Minor scratch repair: grind and repair minor scratches on the sealing surface of the valve core and valve seat to ensure sealing performance.

Annual maintenance:

Oil testing: Test the cleanliness, viscosity and water content of the system oil to ensure compliance with usage requirements (such as ISO 4406 Class 20/18/15 or NAS level 7).

Filter element replacement: Replace the system filter element to prevent impurities from entering the valve body.

Oil change treatment: If the oil deteriorates due to oxidation, becomes darker in color, smells bad, or becomes milky white, it needs to be replaced with new oil in time.