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Time：2025-08-11 13:59:57 Reading volume：
The higher the filtration precision of an oil purifier, the better. The selection should be based on a comprehensive consideration of the oil type, equipment requirements, and actual operating conditions. The following is a key analysis:
1. Disadvantages of Excessive Filtration
- Loss of Oil Additives:
High-precision filter elements (e.g., <1 micron) may adsorb effective additives (such as anti-wear agents and antioxidants) in the oil, reducing oil performance.
For example, ZDDP (anti-wear agent) in hydraulic oil may be partially retained by ultrafine filter media.
- Increased Energy Consumption and Cost:
Higher filtration resistance increases filtration resistance, leading to increased energy consumption and more frequent filter element replacements (for example, nanofilter elements cost 3-5 times more than ordinary filter elements).
- Reduced Flow Rate:
High-precision filtration takes longer, impacting production efficiency.
2. Limited Applicability:
Submicron filtration is only necessary for systems containing ultrafine particles (such as silicates and colloids) or for precision systems (such as aircraft hydraulic systems and semiconductor equipment lubrication).
1. Reference Oil and Equipment Standards
| Oil Type | Recommended Filter Size | Based on Standard |
|------------------------------------------|-----------------------------|--------------------------------------------------|
| Transformer Oil | 1-3 microns | IEC 60422 (Dissipation Value Requirements) |
| Hydraulic Oil (High-Pressure System) | 3-5 microns | ISO 4406 NAS Grade 7 |
| Gear Oil | 10-25 microns | AGMA 9005 (High Viscosity Tolerance) |
| Turbine Oil | 5-10 microns | DIN 51515-2 |
2. Consider Contamination Type
- Solid Particles: ｓｅｌｅｃｔ a particle size slightly smaller than the equipment's allowable size (e.g., if the bearing clearance is 20 microns, ｓｅｌｅｃｔ a 10-micron filter element).
- Water/Colloids: Requires coalescing separation or vacuum dehydration; simply increasing the filter size is ineffective.
- Incorrect Case:
A steel mill used a 1-micron filter element for gear oil (viscosity 460 cSt). This resulted in:
- The filter element clogged within 2 hours, increasing replacement costs;
- The oil temperature rose by 10°C, accelerating oxidation.
- Correct Solution:
Switch to a 15-micron filter element + a magnetic filter, achieving a balance between cleanliness and economy.
1. Staged Filtration:
First, perform coarse filtration (20-50 microns) to remove large particles, followed by fine filtration (target accuracy) to extend filter element life.
2. Dynamically Adjust Accuracy:
- New oil/lightly contaminated: Standard accuracy.
- Severely contaminated: Initially use a lower accuracy, then gradually increase it.
3. Comprehensive Purification Solution:
For highly contaminated oil, a combination of centrifugal separation (for water removal) + electrostatic purification (for colloid removal) + moderate filtration should be used.
The following scenarios require high-precision filtration (<1 micron):
- Hydraulic systems for precision servo valves (clearance ≤3 microns).
- Nuclear power plant transformer oil (particle count requirements ISO 14/12/9).
- Food-grade lubricants (FDA requirements for no residual particles).
Filter selection should follow the principle of "sufficient for the purpose," balancing cleanliness requirements, oil performance, and economic benefits. It is recommended to prioritize equipment manufacturer requirements and verify results through oil testing (such as particle count and PQ index).
