Hydraulic Protection
Maintaining cleanliness targets in hydraulic circuits to protect proportional valves, servo valves, and high-pressure pumps with sub-10 µm clearance tolerances.
FAILURE MECHANISM
Particles in the 5–15 µm clearance range of proportional valve spools → spool stiction → valve position error → pressure and flow control instability → machine motion faults → unexpected movement. Hard particles >3 µm in high-pressure pump clearances → abrasive wear → pump efficiency loss → heat generation → seal failure.
5–10 µm
Proportional valve clearance
ISO 18/16/13
NFPA T2.14 minimum
Per approved application
NANOFORCE™ Beta ratio
–15–30% without control
Equipment availability impact
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Contamination Target
Hard particles in the 1–15 µm range, targeting ISO 4406 16/14/11 for proportional systems and ISO 18/16/13 minimum per NFPA T2.14.
TARGET CLEANLINESS
ISO 4406 16/14/11 for proportional valve systems; ISO 18/16/13 minimum (NFPA T2.14); ISO 15/13/10 for servo valve systems.
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Proportional Valve Protection
Proportional valves and servo valves control hydraulic flow and pressure in direct proportion to an electrical input signal. Spool-to-bore clearances of 5–10 µm make these valves highly sensitive to particle contamination. Hard particles trap between spool and bore, increasing breakout friction (stiction) and causing position hysteresis — the actual valve position lags the commanded position. NFPA T2.14 mandates ISO 18/16/13 minimum cleanliness for systems containing proportional control valves.
2–5 µm
Servo valve clearance
5–10 µm
Proportional valve clearance
10–25 µm
Gear pump clearance
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Commissioning Flush Protocol
New hydraulic systems contain manufacturing residue (machining chips, pipe scale, welding slag, sealing compound). Commissioning flush — circulating filtered oil at elevated flow rate through dedicated flush circuits before first operation — is essential to achieve target cleanliness. System cleanliness should be verified by particle counting (ISO 11171 calibrated APC) before connecting servo or proportional valves.
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Offline Kidney Loop Filtration
Offline kidney loop filters — independent filtration circuits that draw from and return to the reservoir — provide continuous particulate removal independent of system operation. Unlike pressure and return line filters that only filter during machine operation, kidney loops maintain reservoir cleanliness during standby. Recommended flow rate: 10–15% of reservoir volume per hour for steady-state maintenance filtration.
ELIMFILTERS TECHNOLOGIES FOR THIS SYSTEM