The difference between air pressure oil filter and vacuum oil filter

Pneumatic oil filter and vacuum oil filter are two common oil purification equipment, mainly used for filtering and dehydrating industrial lubricating oil, insulating oil, hydraulic oil, etc. The core difference between them lies in the working principle and applicable scenarios, and the specific comparison is as follows:

1. Working principle

- Pneumatic oil filter (pressure oil filter)

- Push the oil through the filter element or filter membrane by pressurizing (positive pressure), and rely on mechanical extrusion and adsorption to remove impurities, moisture and particulate matter.

- Typical structure: oil pump pressurization → multi-stage filter (such as coalescing filter element, particle filter element) → output clean oil.

- The dehydration capacity is limited, and it mainly relies on the adsorption or coalescence of the filter material to remove a small amount of moisture.

- Vacuum oil filter

- Reduce the boiling point of the oil through a negative pressure (vacuum) environment, so that the water evaporates at a low temperature (vacuum dehydration), and combine mechanical filtration to remove impurities.

- Typical process: oil heating → vacuum separation tank (water evaporation) → precision filtration → output.

- Strong deep dehydration capability, especially suitable for oil with high water content (such as transformer oil).

2. Comparison of core functions

| Function | Air pressure oil filter | Vacuum oil filter |

|----------------|-----------------------------|--------------------------------|

| Impurity removal | Depends on the filter element accuracy, can remove tiny particles | Combined with mechanical filtration, equally efficient |

| Dehydration | Can only handle a small amount of free water (≤5%) | Can completely remove free water and emulsified water (≤100ppm) |

| Degassing | No degassing function | Can remove dissolved gases in oil (such as air, hydrogen) |

| Heating | Usually no heating or low temperature heating | Requires heating (50~70℃) to assist vacuum dehydration |

3. Applicable scenarios

- Air pressure oil filter

- Suitable for impurity filtration of low water content oil (such as hydraulic system maintenance, lubricating oil circulation purification).

- Advantages: simple structure, small size, low cost, easy maintenance.

- Vacuum oil filter

- Suitable for oil with high water content or deep purification (such as transformer oil regeneration, turbine oil dehydration and degassing).

- Advantages: high dehydration efficiency, can handle emulsified oil; Disadvantages: complex equipment, high energy consumption.

4. Other differences

- Energy consumption: vacuum oil filter needs to be heated and maintained in vacuum, and its energy consumption is significantly higher than that of an air pressure oil filter.

- Processing speed: air pressure oil filter usually has a larger flow rate and is suitable for rapid filtration; vacuum oil filter has a slower dehydration process.

- Oil adaptability: The vacuum oil filter is less effective for high-viscosity oil (such as gear oil) and requires additional heating.

Summary of selection suggestions

- Choose an air pressure oil filter: the water content of the oil is low, the pollution is mainly particle pollution, the budget is limited, or portability is required.

- Choose a vacuum oil filter: The oil has a high water content (or emulsification), and needs to be degassed and dehydrated at the same time, such as insulating oil treatment in the power industry.

Comprehensively ｓｅｌｅｃｔ according to the actual oil pollution type, water content and purification target, and can be used in combination if necessary (such as vacuum dehydration first and then air pressure fine filtration).