Introduction of hydraulic oil dehydration and filtration equipment

Selection and technical guide for hydraulic oil dehydration and filtration equipment

Water in hydraulic oil can lead to problems such as reduced lubrication performance, component corrosion, and cavitation damage, so professional equipment must be used for dehydration and purification. The following are the key equipment types, technical principles, and selection recommendations for hydraulic oil dehydration and filtration.

Hazards of water in hydraulic oil

| Type of water | Impact | Allowable water content (typical) |

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

| Free water | Deposit at the bottom of the oil tank, accelerate oxidation | ≤0.1% (1000ppm) |

| Emulsified water | Form a stable emulsion, block the filter element | ≤0.05% (500ppm) |

| Dissolved water | Molecular dispersion, promote acid value increase | ≤100ppm (precision system requires ≤50ppm) |

Types of hydraulic oil dehydration and filtration equipment

(1) Vacuum oil filter (best deep dehydration solution)

- Principle: Heating in a vacuum environment (60-70℃), the water evaporates and condenses out.

- Dehydration capacity:

- Free water → ≤50ppm

- Dissolved water → ≤30ppm (high vacuum type)

- Applicable scenarios:

- High-pressure hydraulic system (such as injection molding machine, construction machinery)

- Servo hydraulic oil purification

(2) Coalescing separation oil filter (emulsification + dehydration)

- Principle:

1. Coalescing filter element: Tiny water droplets merge into large water droplets

2. Separation filter element: hydrophobic material blocks oil from passing through, and free water settles

- Dehydration capacity:

- Emulsified water → ≤100ppm

- Advantage: No heating required, suitable for flammable environments (such as coal mine hydraulic supports)

(3) Centrifugal oil filter (high-pollution oil pretreatment)

- Principle: high-speed rotation (5000- 8000 rpm) to separate water and oil.

- Dehydration capacity:

- Free water → ≤0.05%

- Disadvantages: Unable to remove dissolved water, must be used with vacuum equipment.

(4) Adsorption dehydration device (trace water polishing)

- Principle: Molecular sieve/silica gel adsorbs residual dissolved water.

- Dehydration capacity:

- Dissolved water → ≤20ppm (ultra-precision system)

- Typical applications:

- Wind power hydraulic pitch system

- Aviation hydraulic oil maintenance

Maintenance recommendations

1. Regular inspection:

- Use Karl Fischer titrator (ASTM D6304) to monitor water content

- Check the filter pressure difference every month (＞0.3MPa needs to be replaced)

2. System coordination:

- Install air air-dry respirator on the oil tank (to prevent water inhalation)

- Online dehydration device (continuously controls water ≤100ppm)

The selection of hydraulic oil dehydration equipment requires comprehensive consideration of water type, system accuracy requirements and operation and maintenance costs. For key equipment (such as a servo hydraulic system), a vacuum + coalescence combination solution is recommended, equipped with an online monitoring function. Free oil sample testing and solution design services are provided. Welcome to consult specific needs!