Hydraulic fluids FAQ

What are some things to remember about suction filters when using water-glycol type hydraulic fluid?

• Set the suction resistance to 120 × 102 Pa (90 mmHg) or less.
• A design with a filter capability that is between 1.5 and 2 times the suction flow rate of the pump is desirable.
• The best material to use is stainless steel.

What are some things to remember about pumps when using water-glycol type hydraulic fluid?

This fluid can be used with single-stage (7 MPa) and double-stage (14 MPa) standard-type vane pumps, single-stage high-pressure vane pumps (14 MPa), inscribed gear pumps (21 MPa), and axial piston pumps (21 MPa).
For details regarding your design, contact your hydraulic equipment manufacturer.

What are some things to remember about level gauges when using water-glycol type hydraulic fluid?

• As much as possible, use inorganic materials, such as glass.
• If synthetic resin is necessary, use acrylic, vinyl chloride, or polypropylene that has been shaped through machining.
• Avoid using polycarbonate resin because this material has a tendency to crack.

What are some things to remember about painting and fluid tanks when using water-glycol type hydraulic fluid?

• Do not paint the inside surfaces of fluid tanks.
• Vinyl resin or epoxy resin types of paints are suited to the painting of the outside surfaces of hydraulic equipment, but do not expect that these paints will last for a long time.
• Except for its air breather, keep the fluid tank in an air tight condition as much as possible. • Attach a cooler to keep the fluid temperature at 50°C or lower.

What are some things to remember about the seals, hoses, and accumulators of a hydraulic system when using water-glycol type hydraulic fluid?

• Avoid using objects that absorb water such as hides, cork, and paper.
• Under normal usage conditions, nitrile rubber is the optimum material to use. If the temperature will be relatively high, EP rubber is the optimum material to use. (However, EP rubber is not well suited to use with mineral oil.)
• Avoid using urethane.
• We recommend that you use a high-pressure hose that meets the specifications of water-glycol type hydraulic fluid.

What are some things to remember about the metal materials of a hydraulic system when using water-glycol type hydraulic fluid?

Avoid using zinc, zinc-plated objects, cadmium, and cadmium-plated objects because these generate deposits.
Avoid using magnesium because it can be corroded.
Avoid using aluminum because its use for a long period of time or it coming in contact with galvanic metals can lead to pitting and electrolytic corrosion.

What can you tell me about the flushing method?

• Remove as close to all of the previously used oil as possible, and then perform sufficient flushing with a dedicated flushing fluid or with new fire resistant hydraulic fluid. After the flushing operation is finished, remove as close to all of the used fluid as possible.
• When installing new equipment or when changing from mineral-oil-type hydraulic fluid or another type of fire resistant hydraulic fluid, failing to perform flushing or failing to use flushing fluid may lead to poor performance and the generation of undissolved solids, so we recommend that you perform flushing thoroughly.
• The flushing method may vary depending on the type of oil that was previously used, so contact MORESCO for details. MORESCO provides dedicated flushing fluid for rent.

What can you tell me about the usage temperature range of water-glycol type hydraulic fluid?

Hydraulic machinery is designed under the assumption that the hydraulic fluid will be kept at a reasonable temperature (from approximately 40 to 50°C). Especially for HYDOL HAW, of which approximately 40% is water, pay close attention to the temperature of the hydraulic tank, making sure that it does not exceed 50°C.

What can you tell me about the usage standards for HYDOL HAW?

• We have set the following usage standards to ensure that the product is used in its optimum state. Outer appearance: Red Dynamic viscosity: 46.0 to 56.0 Water content (%): 37 to 43 Alkali value: 130 to 170 pH: 9.0 to 11.0 Mineral oil content: Less than 1% Foreign elements: Traces or less • To keep the hydraulic fluid within these standard values, we have set "Water content (%): 38" and "Alkali value: 135" as regulated standards. If the fluid used falls below these standard values, you will have to supplement the fluid with water and the specified alkali value regulating agent.
• The standards that have to be managed vary depending on conditions such as the design conditions and the usage conditions. However, if, even after analyzing and then regulating the fluid, the set usage standards cannot be maintained, you will have to change the fluid.

What can you tell me about the causes and effects of water content changes of water-glycol type hydraulic fluid?

Evaporation causes the water content to decrease.
If the water content is too low, problems may occur due to the deterioration of the flame retardant performance and the increase in dynamic viscosity. Examples of these problems include loss of energy, loss of pressure, decrease in mechanical efficiency, and cavitation erosion.
Supplying an excessive amount of water or mixing with water from an external source due to a problem such as cooler damage cause the water content to increase.
If the water content is too high, the dynamic viscosity will decrease, which will cause problems such as an increase in wear due to a decrease in lubricating properties, decreased efficiency due to leaks within the pump, and difficulty in performing precise control.

What can you tell me about the causes and adjustment methods of dynamic viscosity changes of water-glycol type hydraulic fluid?

We can think of two causes of dynamic viscosity changes.
1. Dynamic viscosity changes caused by water content changes
If the water content is too low, follow the instructions in the lubrication management table to supply additional water.
If the water content is too high, there is a danger of problems occurring, so contact your MORESCO sales representative.
2. Dynamic viscosity changes caused by product degradation
This is a difficult cause to make adjustments for. If the hydraulic fluid is too far from the managed standards, you will have to change it.

What can you tell me about the water to supply?

Even if the water contained in the hydraulic fluid is at room temperature, it will evaporate little by little. You have to supply water to match the usage conditions. Supply distilled water, deionized water, or water condensed from the boiler. No matter which type of water you use, ensure that all impurities have been removed from it.

What can you tell me about filter maintenance and management?

• Filters must be inspected at least once per month. Note that there might be some minor changes to this instruction depending on the usage conditions and environment.
When you inspect the filters, remove them and wash them thoroughly with hot or cold water.
• As much as possible, avoid mixing in fat and oil components such as mineral oil and grease because these react to water-glycol additive agents to produce undissolved solids in the form of sludge, which may lead to filter clogs. If you cannot avoid mixing in these components, periodically remove them to keep the concentration of fat and oil components such as mineral oil and grease to less than 1% of the entire mixture.

What can you tell me about how to inspect water-glycol type hydraulic fluid?

• After you start operations using water-glycol type hydraulic fluid, generally perform an inspection once every 2 to 4 months (1,500 to 3,000 hours). Adjust the rate of inspections to match your usage conditions.
• Regarding samples for inspections, MORESCO will perform an analysis in terms of each standard value that we use and then report the results in a "Lubricating Oil Management Test Results Report."