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Time：2025-04-14 13:48:24 Reading volume：
In hydraulic systems, water contamination can lead to oil oxidation, metal parts rust, and reduced lubrication performance, and must be separated and removed in time. The following are professional methods and operating steps for separating water from hydraulic oil:
Depending on the water content and system requirements, the following 5 mainstream technologies can be selected:
1. Vacuum dehydration (efficient removal of dissolved water)
- Principle: Use vacuum negative pressure to lower the boiling point of water and evaporate the water at a low temperature.
- Equipment: Vacuum oil filter (with condensation device).
- Applicable: dissolved water (<500ppm) or emulsified water.
- Operation:
- Heat the oil temperature to 50~60℃ (avoid exceeding 65℃).
- Vacuum to below -0.095MPa, and circulate until the water content is ≤100ppm.
2. Centrifugal separation (rapid removal of free water)
- Principle: Use centrifugal force to separate water (density> oil) and solid particles.
- Equipment: Centrifugal oil filter.
- Applicable: high water content (>1000ppm) or free water.
- Advantages: no heating required, fast processing speed.
3. Coalescing filtration (for emulsified water)
- Principle: small water droplets are merged into large water droplets through the coalescing filter element, and then discharged through the separation layer.
- Equipment: Coalescing dehydration oil filter.
- Applicable: stubborn emulsified water (oil and water are evenly mixed).
4. Adsorption drying (deep dehydration)
- Material: molecular sieve, silica gel, or super absorbent resin.
- Method:
- Load the adsorbent into the bypass circulation system of the oil filter.
- Or directly add the adsorption bag (need to be replaced regularly).
- Note: The adsorbent needs to be replaced in time after saturation, otherwise it will release water in reverse.
5. Standing drainage (simple emergency)
- Operation:
- Open the drain valve at the bottom of the oil tank after shutdown to release free water.
- Only applicable to situations where water stratification is obvious (limited effect).
1. Detect water content:
- Use a Karl Fischer titrator or rapid test paper to confirm water content.
2. Equipment connection:
- Connect the inlet and outlet of the oil filter to the circulation pipeline of the hydraulic system (bypass mode).
3. Dehydration process:
- Start the vacuum pump → heat the oil → circulate and filter (detect water content every hour).
4. Verification results:
- Water content ≤100ppm (ISO 4406 standard) is qualified.
1. Safety regulations:
- It is strictly forbidden to exceed 65℃ during heating to prevent oil oxidation.
- The vacuum equipment needs to be grounded to avoid static electricity igniting oil vapor.
2. System protection:
- After dehydration, check whether the hydraulic pump and valve block are rusted.
- ｒｅｐｌａｃｅ damaged seals (water will accelerate aging).
3. Preventive measures:
- Install an air dryer on the oil tank to prevent moisture from entering.
- Check the cooler regularly for leaks (internal leaks will introduce moisture).
Q: Can hydraulic oil with severe emulsification be restored?
A: You can try vacuum dehydration + coalescence filtration combined treatment. If it still doesn't work, you need to change the oil.
Q: Do I need to change the filter after the moisture content reaches the standard?
A: It must be changed! Moisture will reduce the life of the filter element and may leave colloid residue.
Q: Can an edible oil dehydrating agent be used to treat hydraulic oil?
A: No! A special dehydrating agent for hydraulic oil (such as Tri-Dry™) is required.
- ISO 4406: Hydraulic oil particle and water contamination levels.
- NAS 1638: Military-grade hydraulic oil cleanliness standard.
By properly selecting separation technology, water can be removed efficiently and the life of the hydraulic system can be extended. For large equipment, it is recommended to equip an online moisture monitor for real-time warning!
