They sound similar. Some suppliers even use them interchangeably.
But in reality, they are not the same tool, and choosing the wrong one = wasted money + your hydraulic system still stays dirty.
This blog breaks down the differences in a simple, practical way, so you can decide confidently.
TYA Series Vacuum Hydraulic Oil Filtration SystemFiltration vs. Purification — The Core Difference
Think of it this way:
Filtration = Removes solids (particles, metal debris, sludge)
Purification = Removes water + gases + fine contaminants
| Function | Filtration System | Purification Machine |
| Removes particles | Yes | Yes (but secondary) |
| Removes water (free + emulsified + dissolved) | No | Yes |
| Removes gases/air | No | Yes |
| Best for | Dirty oil, solid contamination | Milky oil, water ingress, oxidation issues |
| Technology | Filter elements | Vacuum dehydration / thermal evaporation / coalescing |
| Typical result | Particle count improvement | Moisture removal + oil restoration |
If your oil looks dirty → choose Filtration.
If your oil looks milky → choose Purification.
What Is a Hydraulic Oil Filtration System?
A filtration system is designed to remove solid contaminants using filter elements.
What it does well
Removes particles (3–10 microns depending on filter)
Controls ISO cleanliness code
Protects pumps, valves, and precision components
Simple, low cost, low maintenance
What it CANNOT do
Does NOT remove emulsified water
Does NOT break oil-in-water emulsions
Does NOT remove dissolved moisture or gases
If your oil turns milky, filtration won’t fix it — you’ll just clog filters endlessly.
Best use case
Regular maintenance filtration
Offline kidney-loop cleaning
Before filling new oil
When the system has metal debris / wear particles
What Is a Hydraulic Oil Purification Machine?
A purification machine goes beyond filtration. It can remove water, gases, and volatile contaminants, often using vacuum dehydration.
What it does well
Restores milky hydraulic oil
Removes free water + emulsified water + dissolved water
Removes entrapped air & gases
Improves oxidation stability
Recovers high-value oils
What it CANNOT do
Cannot replace normal filtration for particle control
Cannot fix mechanical wear issues upstream
Best use cases
Milky / cloudy hydraulic oil
Water contamination in press machines, marine hydraulics, injection molding machines, turbines
Systems running in humid or outdoor environments
When Should You Use Which?
| Situation | What You See | Correct Solution |
| Metal particles in oil | Dark oil, glitter, high ISO code | Filtration system |
| Oil turns milky | White/cloudy oil | Purification machine |
| Water at bottom of tank | Free water separation | Purification (centrifugal or vacuum) |
| High moisture level but oil looks normal | High ppm reading | Purification machine |
| New oil filling | Avoiding contamination | Filtration system |
| Routine maintenance | Controlling particle cleanliness | Filtration system |