How to Remove Water From Hydraulic Oil

Water and oil do not mix. This rings true especially when it comes to hydraulic oil. If you’ve noticed hazy or cloudy oil, water contamination is the likely culprit. Water contamination can heavily impact hydraulic system performance, causing unnecessary wear and tear and shortening the life expectancy of your machinery.

You can preserve the life of your machinery by catching water contamination early, taking fast action to remove water from hydraulic oil and preventing further contamination. Choosing the right filter can also help eliminate contamination.

Learn how to test for water in hydraulic oil and some effective removal methods.

Water Contamination in Hydraulic Systems

A common cause of hydraulic system failure, water degrades the existing lubricant and increases the risk of rust. By chemically reacting with the fluid and its additives, water can cause hydrogen embrittlement and catalyze oxidation, leading to accelerated oil degradation.

Water in hydraulic fluid leads to machinery issues like:

• Oxidization and freeze damage.
• Rust and wear.
• Oil degradation.
• Cavitation in machine pumps.
• Reduced fluid efficiency and elasticity.
• Internal corrosion.

Common Causes of Water Contamination

Water contamination occurs when moisture finds its way into the system. Some common causes include:

• Leaks in the seal.
• Condensation due to temperature changes.
• Rain leakage.
• Improper handling.

Identify the Type of Water Contamination

The first step in removing water contaminants from hydraulic systems is identifying the type of water present. Depending on the type and amount of water contamination in the hydraulic oil, you can choose the most effective removal technique.

1. Dissolved Water

Dissolved water is typically brought in by moist air absorbed by the oil. Water in this stage is allowable up to the saturation point, after which the fluid cannot hold any more. Any water above this saturation point can lead to rust and decreased lubrication. Typically, machinery like hydraulics and gears allows 100 to 600 parts per million (ppm) of water, depending on the oil’s saturation point and the specific system.

Since this stage is difficult to detect visually, the Karl Fischer laboratory test can best determine if water is present. A sample is sent to a lab, and the hydraulic fluid is tested to detect the amount of water present.

2. Emulsified Water

Once the saturation point is reached, the water appears in an emulsified state. These microscopic water droplets cause the oil to look cloudy or hazy. This type of contamination is more detrimental to the system than dissolved water, so it is more important to catch it early.

Emulsified water is typically easy to detect visually due to the hazy oil color. However, if there is doubt about the presence of emulsified water, performing the crackle test can provide a better answer.

The crackle test involves three main steps:

1. Heat a hot plate up to 320 degrees Fahrenheit.
2. Take a sample of the oil, making sure to mix it well to integrate any water.
3. Using a syringe, place a drop of the oil onto the hot plate.

If there is no reaction, your oil is free from emulsified water. If you see any bubbles forming, this could indicate the presence of water contamination. Sending the sample to a lab to perform a Karl Fischer test can determine the amount of water present.

3. Free Water

Free water is the most detrimental water contamination for hydraulic oil, and the most easily identifiable. This water has separated from the oil, forming a layer at the bottom of the oil.

Draining this layer is the most inexpensive way to remove this contamination. Most systems allow for easy drainage, and automatic drain valves can maximize time efficiency.

Best Ways to Remove Water From Hydraulic Oil

Once you have determined the type of water contaminant, you can choose the best removal process.

Vacuum Dehydration

Vacuum dehydration can remove all three types of water contamination but is especially helpful with dissolved water. Exposing water to a vacuum lowers its boiling point, allowing it to evaporate from the system.

The steps to vacuum dehydration are as follows:

1. Transfer the oil to a vacuum dehydration unit, sealing the chamber.
2. Activate the vacuum pump, removing the air from the chamber and reducing the atmospheric pressure.
3. This pressure reduction lowers the water’s boiling point, causing it to evaporate.
4. Use spray nozzles or a spinning disk to spread the oil into a thin film to enhance evaporation.
5. The water vapor is passed through a condenser, where it is cooled and returned to its liquid state.
6. When the desired level of water removal is achieved, the decontaminated oil can return to its system and the removed water is disposed of.

To perform a vacuum dehydration, you can purchase a vacuum dehydration unit or hire a fluid management service to perform the removal. Organizations that encounter this problem frequently may find it more cost-effective to purchase a unit for in-house use.

This removal method is highly effective and safe for most oil types. However, it may cost more than other methods, and installing a vacuum dehydrator requires professional help.

Centrifugal Separation

Centrifugal force can separate water from the hydraulic fluid. Spinning the fluid in a centrifuge separates its makeup based on density, pushing water and other contaminants to the edge of the bowl. The centrifugal machine drains the water out, leaving clean oil behind.

Centrifugal separation:

• Removes free water and most emulsified water.
• Removes sludge and solid particles in addition to water.
• Provides an option for batch or continuous operation that allows for ongoing cleaning.

Similar to vacuum dehydrators, these centrifugal machines usually have a high initial cost and require regular maintenance. In addition, centrifugal separation is not effective at fully eliminating emulsified water. This method works best for free water and emulsified water.

Filtration Methods

Hydraulic filters are installed within the system, separating water from the fluid by passing the liquids through a filter.

There are two main types of filters:

1. Absorption filters: These filters are made of materials that absorb water, like polymer fibers. Catching free water in the filter, the clean oil passes through. A cost-effective option for smaller machines, these filters must be replaced once they reach saturation.
2. Coalescing filters: This filter coalesces the water contaminant, combining water droplets into larger ones that separate from the oil. This water is then removed from the oil through the filtration system. Typically used for emulsified and free water, these filters can be used in larger hydraulic systems.

The lowest-cost option, hydraulic filters are easy to install and maintain. They also take up less space than centrifuges and vacuum machinery.

Preventing Hydraulic Oil Contamination

In addition to these removal practices, taking care of the hydraulic system can help prevent water contamination. Some preventive measures include:

• Fluid replacement: Regularly check the fluid levels at least twice a year, and replace the fluid at regular intervals.
• Inspections: Visually inspect the system for leaks, hazy oil color and other indicators of contamination.
• Maintenance: Perform routine maintenance on the system, abiding by the manufacturer’s recommendations.
• Monitoring: Install online sensors that can aid in monitoring the water level or perform oil analyses.

Partner With Chase Filters & Components for Fluid Purity

As a leader in filter manufacturing, Chase Filters & Components offers a variety of products that can free your hydraulic fluid from water contamination. Our selection of filters can help prevent corrosive damage to your systems, cutting down on unnecessary repair costs.

Contact us today to learn more about our filters and find an option that works best for your needs.