1. Solid Particles
Sources: Environmental dust, metal wear particles from gears/pumps, welding slag from new machines, dirt ingress during maintenance.

Damage: Particles smaller than a human hair work like lapping compound, grinding away at pump internals, valve spools, and bearing surfaces. A particle of just 5 microns can stick a servo valve with 2-5 micron clearances.

Filtration Solution: Multi-stage depth filtration using micro-glass or synthetic media that capture particles down to 1 micron absolute. This is the core of any kidney loop system.

2. Water
Sources: Humidity (especially in coastal areas), heat exchanger leaks, mould cooling water leaks, washdown processes.

Damage: Water causes rust, reduces oil lubricity, accelerates oxidation (every 10°C temperature rise doubles the oxidation rate, and water catalyses this), and leads to pump cavitation. Water exists as free, emulsified, or dissolved – all are destructive.

Filtration Solution: Vacuum dehydration. The oil is heated to ~55°C and sprayed into a vacuum chamber. At low pressure, water boils at just 50°C, turning into vapour that is extracted. This removes all three forms of water in a single process.

3. Varnish & Oxidation Products
Sources: Thermal degradation of oil at high operating temperatures (above 60°C). Common in injection moulding machines, die-casting, steel mills, and turbine EHC systems.

Damage: Varnish is a sticky, gum-like deposit that coats servo and proportional valves, causing sluggish response, sticking, and seizure. It insulates heat exchangers, raising oil temperature further and accelerating more varnish formation – a vicious cycle. Varnish starts as dissolved oxidation products that standard mechanical filters cannot capture.

Filtration Solution: Electrostatic oil cleaning. High-voltage DC electrodes attract charged varnish precursors and sub-micron particles, permanently depositing them on collector plates. Removes contaminants down to 0.01 microns – well below the range of mechanical filters.