Fluid Cleanliness Management

Target cleanliness code selection

Set by the most sensitive component in the fluid circuit. Servo valves (1–3 µm clearance): ISO 14/12/9. Proportional valves (5–10 µm): ISO 16/14/11. Engine bearings (5–25 µm): ISO 16/14/11. Gear pumps (15–30 µm): ISO 19/17/14. The target establishes the Beta ratio and absolute rating required at the specified ingress rate.

New oil cleanliness

New oil from the drum is NOT clean to system specification — typical new oil is ISO 18/16/13 or worse. Filling a clean system with new oil from unfiltered containers introduces contamination. Filter transfer carts or kidney loop conditioning are required before fill.

Oil analysis program

Combines particle counting (ISO 4406 code), elemental spectroscopy (ICP — wear metals by element), and physical properties (viscosity, TAN, TBN, water content). Each data stream provides different diagnostic information. Trend analysis over consistent sampling intervals has more diagnostic value than single-point measurements.

Sampling methodology

Samples must be drawn from live zones (not stagnant lines), in representative bottles (pre-cleaned to ISO 14/12/11 or better), at consistent points in the system. Sampling from the bottom of a sump or from a drain valve captures settled contamination, not representative system fluid.

Wear metal patterns

Elemental spectroscopy maps wear sources: iron = steel components (rings, cylinders, gears); chromium = chrome-plated bores/rings; aluminum = pistons/housings; copper/tin = bearings; silicon = dirt ingress or sealant degradation. Silicon increase in lube oil typically indicates air intake breach.

Servo valve cleanliness target[NFPA T2.14]

ISO 14/12/9

Engine lube target

ISO 16/14/11

Hydraulic motor target

ISO 17/15/12

Gear pump target

ISO 19/17/14

Flush target before commissioning

ISO 17/15/12

New oil typical cleanliness

ISO 18/16/13