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8.1 Purpose of Bio Hydraulic Fluids
United Bio Lube's Bio Hydraulic Fluids are engineered to meet the physical demands of modern hydraulic systems:
(1) Efficient Power Transmission
Bio Hydraulic Fluids are incompressible fluids that flow easily and efficiciently transmit power throughout hydraulic power systems. Bio Hydraulic Fluids ensure stable and reliable operation of components, such as Servos and Control Valves.
(2) Superior Lubricity
Bio Hydraulic Fluids provide outstanding lubricating characteristics and qualities necessary to protect all hydraulic system components against Friction, Wear, Oxidation, Rust, and Corrosion. These protective qualities are achieved through the use of patented Stabilized High Oleic Base Stocks compounded with an environmentally friendly Zinc-free additive system.
(3) Anti-Leak & Non-Drip Protection
Bio Hydraulic Fluids are engineered to prevent leaks by conditioning Seals and Hoses. Proper conditioning keeps Seals and Hoses from degrading and prevents fluid from egressing into sensitive areas. Leaking fluid causes pressure changes and system overheating.
AP NOTE: Many hydraulic system components, such as Control Valves, operate with tight clearances where seals are not provided. In these applications, Bio Hydraulic Fluids provide the required seal between the low pressure and high pressure side of valve ports. The amount of leakage depends on the closeness or the tolerances between adjacent surfaces and fluid viscosity.
(4) Cooling, Heat Transfer
Circulating Bio Hydraulic Fluids are capable of removing heat generated throughout the system. Stabilized chemistry provides Cold Flow Technology for reliable pumpability at extreme sub-zero temperatures.
(5) Compatibility with Seals, Elastomers, and Existing Fluids
Bio Hydraulic Fluids are proven compatible with hydraulic system materials and components that are designed to operate on mineral oil based and synthetic based hydraulic fluids.
Bio Hydraulic Fluids have been tested and proven to be compatible with Mineral Oil based and most Synthetic fluids.
(6) Safety
Designed with safety in mind, United Bio Lube's Bio Hydraulic Fluids are 100% Ultimate Biodegradable, non-hazardous, non-toxic, and free of Heavy Metals.
The extremely Low Volatility of Stabilized HOBS increases the Flash Point and fire safety features in these biobased hydraulic formulas.
8.2 Physical Properties
The physical properties of Bio Hydraulic Fluids are similar to those physical properties already discussed for Biobased oils in Chapter 3 - Physical Properties. Only those properties requiring additional discussion are addressed below.
Viscosity Index
United Bio Lube's Bio Hydraulic Fluids provide superior lubricity in high pressure/high temperature hydraulic systems. This lubricity factor is measured by an extremely high Viscosity Index (VI), i.e. VI = 216.
Viscosity
As with lubricating oils, Viscosity is a very important property defining a Bio Hydraulic Fluid. The viscosity of a fluid has a significant impact on the operational performance of a hydraulic system; and, is the single most important factor when selecting a hydraulic fluid.
If the Viscosity is too high, then Friction, Pressure Drop, Power Consumption, and Heat Generation will increase creating sluggish operation of valves and servos.
If the Viscosity is too low, increased internal leakage may result under higher operating temperatures. In this case, the Fluid Film may be insufficient to prevent excessive wear or possible seizure of moving parts. Ultimately, pump efficiency may decrease and sluggish operation may result.
Mono-Grade (ISO Viscosity Grades)
If the hydraulic system has a narrow operating temperature range, then it is possible to maintain optimum fluid viscosity using a Mono-Grade fluid. Stabilized Bio Hydraulic Fluid formulations allow for a range of ISO Viscosity Grades, i.e. ISO 32, ISO 64, ISO 68, etc...
Multi-Grade Performance
Conversely, Multi-Grade Bio Hydraulic Fluid (i.e. Bio Ultimax™ AW 1000 Hydraulic Fluid - 10W40) is recommended for hydraulic systems operating in broad temperature ranges. Multi-Grade is required to maintain viscosity within permissible limits across a wide operating temperature range.
The super high Viscosity Index of the Stabilized High Oleic Base Stocks (HOBS) formula provides advanced Multi-Grade performance.
Use of a Multi-Grade hydraulic fluid maximizes the overall efficiency of a hydraulic system. Multi-Grade fluid can reduce the power consumption of a hydraulic system since less input power is given up to heat.
Cost Saving Feature: This Multi-Grade feature allows for a reduction, or consolidation of inventory, i.e. one Bio Hydraulic Fluid replaces two or more ISO grade petroleum based (mineral oil or synthetic) hydraulic fluids. Use of a Multi-Grade Bio Hydraulic Fluid helps eliminate on site hazardous materials storage, handling, and disposal costs.
Oxidation Stability
The Oxidation Stability of a Bio Hydraulic Fluid is perhaps the most important quality affecting fluid function and Service Life. Physical properties of a Bio Hydraulic Fluid can be expected to change with time. Factors that influence these changes include:
- Mechanical Stress and Cavitation, which can break down and reduced fluid Viscosity.
- Oxidation and Hydrolysis which cause:
- Accelerated Chemical Decomposition
- Formation of Volatile Components
- Precipitation of Insoluble Materials
- Corrosive By-products
Compressibility
Compressibility is a measure of the amount of volume reduction due to pressure. Compressibility increases with pressure and temperature and has significant effects on high-pressure fluid systems. Compressibility is sometimes expressed by the Bulk Modulus, which is the reciprocal of compressibility.
Problems directly caused by Compressibility include the following:
- Servos fail to maintain Static Rigidity.
- Loss in Power, or Energy Efficiency.
- Metal Fractures and Corrosive Fatigue caused by Cavitation.
8.3 Quality Requirements
Note: Quality Requirements for Bio Hydraulic Fluids are discussed in detail in Chapter 4 - Quality Requirements. For reference, the essense of Chapter 4 is summarized below:
The quality of a Bio Hydraulic Fluid is the length of time that the fluid's essential properties will continue to perform as expected, i.e., the fluid's resistance to change with time. The primary properties affecting quality are Oxidation Stability, Rust Prevention, Foam Resistance, Water Separation, and Anti-Wear properties.
United Bio Lube's Bio Hydraulic Fluids incorporate patented Stabilized High Oleic Base Stocks (HOBS) chemistry formulated with a performance boosting Zinc-free adititive package for superior Anti-Oxidation, Anti-Rust, Anti-Corrosion, Anti-Foam, Anti-Wear, and Water Separation properties. Additives are carefully selected to reduce any potential chemical breakdown at high temperatures and pressures.
Oxidation Stability
Oxidation, or the chemical union of oil and oxygen, is one of the primary causes for decreasing the stability of hydraulic fluids. Once the reactions begin, a catalytic effect takes place. The chemical reactions result in formation of acids that can increase the fluid viscosity and can cause corrosion.
Polymerization and condensation produce insoluble Gum, Sludge, and Varnish that cause sluggish operation, increased wear, reduced clearances, plug lines, and clogged valves.
Factors Contributing To Oxidation
The most significant contributors to oxidation include Temperature, Pressure, Contaminants, Water, Metal Surfaces, and Agitation.
(1) Temperature
The rate of chemical reactions, including oxidation, approximately doubles for every 10 °C (18 °F) increase in temperature. The reaction may start at a local area where the temperature is high. However, once started, the oxidation reaction has a catalytic effect that causes the rate of oxidation to increase.
(2) Pressure
As the pressure increases, the fluid viscosity also increases, causing an increase in friction and heat generation. As the operating temperature increases, the rate of oxidation increases. Furthermore, as the pressure increases, the amount of entrained air and associated oxygen also increases. This condition provides additional oxygen to accelerate the oxidation reaction.
(3) Contaminants
Contaminants that accelerate the rate of oxidation may be dirt, moisture, joint compounds, insoluble oxidation products, or paints.
Note: Only a 1 percent sludge concentration in a hydraulic fluid is sufficient to cause the fluid to oxidize in half the time it would take if no sludge were present. Therefore the contaminated fluid's useful life is reduced by 50 percent.
(4) Water and Metal
Certain metals, such as copper, are known to be catalysts for oxidation reactions, especially in the presence of water. Due to the production of acids during the initial stages of Oxidation, the Viscosity and Neutralization Numbers increase. The Total Acid Number (TAN) for a fluid provides a measure of the amount of acid contained in a fluid.
(5) Agitation
To reduce the potential for oxidation, Oxidation Inhibitors, namely patented Stabilized technology, are compounded to the base hydraulic fluid. Two types of inhibitors are generally used: Chain Breakers and Metal Deactivators.
Chain Breaker Inhibitors interrupt the oxidation reaction immediately after the reaction is initiated.
Metal Deactivators reduce the effects of metal catalysts.
Rust and Corrosion Prevention
Rust is a chemical reaction between water and ferrous metals.
Corrosion is a chemical reaction between chemicals (usually acids) and metals.
Water condensed from entrained air in a hydraulic system causes rust if the metal surfaces are not properly protected. In some cases water reacts with chemicals in a hydraulic fluid to produce acids that cause corrosion. The acids attack and remove particles from metal surfaces allowing the affected surfaces to leak, and in some cases to seize.
Air Containment and Foaming
Air Entrainment is a dispersion of very small air bubbles in a hydraulic fluid. When the fluid is depressurized, the air produces foam as it is released from solution.
Foam and high air entrainment in a hydraulic fluid cause erratic operation of servos and contribute to pump cavitation. Fluid oxidation is another problem caused by air entrainment. As a fluid is pressurized, the entrained air is compressed and increases in temperature. This increased air temperature can be high enough to scorch the surrounding oil and cause oxidation.
Demulsibility or Water Separation
Water that enters a hydraulic system can emulsify and promote the collection of dust, grit, and dirt, and this can adversely affect the operation of valves, servos, and pumps, increase wear and corrosion, promote fluid oxidation, deplete additives, and plug filters.
United Bio Lube's Bio Hydraulic Fluids made from Stabilized High Oleic Base Stocks permit water to separate or demulsify readily.
Anti-Wear Properties
United Bio Lube's Bio Hydraulic Fluids are engineered for high pressure (over 6900 kPa or 1000.5 lb/sq in) and high speed (over 1200 rpm) applications that use Vane or Gear pumps. These applications do not permit the formation of Full Fluid Film lubrication to protect contacting surfaces - a condition known as Boundary Lubrication.
Boundary Lubrication occurs when the fluid viscosity is insufficient to prevent surface contact. Anti-Wear additives provide a protective film at the contact surfaces to minimize wear.
At best, use of a bio hydraulic fluid without the proper Anti-Wear additives will cause premature wear of the pumps and cause inadequate system pressure. Eventually the pumps will be destroyed.
8.4 Use of Additives
Note: Various types of additives and their use are discussed in Chapter 5 - Renewable Lubricant Additives. For reference, the essense of Chapter 5 is summarized below:
The quality of United Bio Lube's full line of Biobased Lubricants is surpased by none. High quality performance is established at a state-of-the-art Biobased Lubricants refinery using advanced biobased additive technology. Biobased additives are carefully chosen to be highly effective with Stablilized™ High Oleic Base Stocks, a Premium quality Base Oil.
AP NOTE: Although the overall performance of an fluid can be improved by introducing additives, a poor quality fluid cannot be converted into a premium quality fluid by introducing additives.
An additive may function in any of the following three ways:
1) Protecting Lubricated Surfaces. Extreme Pressure (EP)Additives, Bio Corrosion Inhibitors, and Bio Rust Inhibitors are included in this category. These additives coat the lubricated surfaces and prevent wear, corrosion, and rust.
2) Improving Performance. Viscosity Index Improvers and Anti-Foaming Agents are examples. They make the fluid perform in a desired manner for specific applications.
3) Protecting Biobased Fluids. Stabilized Anti-Oxidant chemistry significantly reduces the tendency of High Oleic Base Stocks to oxidize and form Sludge and Acids.
These three types of additives are discussed individually in the following paragraphs:
1) Surface Additives
The primary purpose of a Surface Additive is to protect lubricated surfaces. Extreme Pressure Agents, Bio Rust Inhibitors, Bio Corrosion Inhibitors, Anti-Wear, and Oiliness additives are included in this category. These additives coat the lubricated surfaces to prevent wear or rust.
Extreme Pressure (EP) Agents
Extreme Pressure Agents react with the metal surfaces to form compounds that have a lower Shear Strength than the metal.
The Extreme Pressure reaction is initiated by an increased temperature caused by the pressure between asperities on wearing surfaces. The EP reaction creates a protective coating at the specific points where protection is required. This coating reduces friction, wear, scoring, seizure, and galling of wear surfaces.
Extreme Pressure additives are used in heavy loading or shock loading applications such as turbines, gears, and ball and roller bearings.
Bio Rust Inhibitors
Bio Rust Inhibitors are added to most industrial lubricants to minimize rusting of metal parts, especially during shipment, storage, and equipment shutdown.
AP NOTE: In some instances, water will remain either suspended by agitation or will rest beneath the fluid on machine surfaces when agitation is absent. Bio Rust Inhibitors work by forming a Surface Film that prevents water from making contact with metal parts.
Bio Corrosion Inhibitors
Bio Corrosion Inhibitors suppress Oxidation and prevent formation of Acids. Biobased inhibitors form a Protective Film on metal surfaces to protect alloy bearings and other metals from corrosion.
Anti-Wear (AW) Agents
Anti-Wear Agents cause a fluid to resist wear by coating metal surfaces. Molecules of the Anti-Wear compound are Polar and attach (adsorb) themselves to metal surfaces.
When Boundary Lubrication conditions occur (direct contact between metal asperities), such as in starting and stopping of machinery, Anti-Wear molecules resist removal more than ordinary oil molecules, thereby reducing friction and wear.
Bio Detergents, Bio Dispersants
Bio Detergents and Bio Dispersants are used primarily in hydraulic systems and internal combustion engines to keep metal surfaces clean by preventing deposits of oxidation by-products, i.e. Corrosion, Sludge.
2) Performance Enhancing Additives
Viscosity Index Improvers, Anti-Foaming Agents, Demulsifiers, and Pour Point Depressants are examples of additives used to improve the quality performance of Biobased Lubricants.
Viscosity Index (VI) Improvers
The Viscosity Index, or VI, is an indicator of the change in viscosity as the temperature is changed. The higher the VI, the less the viscosity of an fluid changes for a given temperature change.
Viscosity Index Improvers' are used to limit the rate of change of viscosity with temperature. These improvers have little effect on fluid viscosity at low temperatures. However, when heated, the improvers enable the fluid viscosity to increase within the limited range permitted by the type and concentration of the additive. This quality is most apparent in the application of Multi-grade Bio Hydraulic Fluids.
Anti-Foaming Agents
Anti-Foaming and Air Release properties make Bio Hydraulic Fluids highly resistant to Foaming and Air Entrapment.
Anti-Foaming additives prevent Reservoir Overflow, Overheating, and Contact between adjacent metal surfaces.
Anti-Foaming additives also eliminate Sponginess in hydraulic systems and prevent damage caused by pump Cavitation. Cavitation causes metal erosion, which damages hydraulic components and contaminates the fluid. In extreme cases, cavitation can cause mechanical failure of system components.
Abnormal Noise in hydraulic systems is often caused by Aeration or Cavitation.
Aeration
Aeration occurs when air contaminates the hydraulic fluid. Air in the hydraulic fluid makes a knocking noise when it compresses and decompresses as it circulates through the system. Symptoms of aeration include Foaming of the fluid and erratic actuator movement. Aeration accelerates degradation of the fluid and causes damage to system components through loss of lubrication, overheating, and burning of seals.
Cavitation
Cavitation is the formation of vapor cavities within the fluid. Cavitation occurs when the volume of fluid demanded by any part of a hydraulic circuit exceeds the volume of fluid being supplied. This causes the absolute pressure in that part of the circuit to fall below the vapor pressure of the hydraulic fluid. This results in the formation of vapor cavities within the fluid, which implode when compressed, causing a characteristic knocking noise.
Demulsifiers
Demulsifiers promote separation of fluid and water in hydraulic systems exposed to water.
Pour Point Depressants
A fluid's Pour Point is the temperature at which the fluid ceases to flow under the influence of gravity. In cold weather, fluid with a high Pour Point makes startup of machinery difficult or impossible.
Pour Point Depressants reduce the size and cohesiveness of the crystal structures, resulting in reduced Pour Point and increased Cold Flow at reduced temperatures
3) Fluid Protective Additives
Fluid Protective Additives are employed to protect the biobased fluid instead of the equipment. Oxidation Inhibitors and Anti-Foam Inhibitors are examples.
Oxidation Inhibitors
Oxidation of High Oleic Base Stocks (HOBS) is a major issue in industry, as HOBS tends to readily oxidize. Until the advent of Stabilized, a patented bio processing technology, Oxidation has kept most industries from broadly adopting vegetable-based fluids as their prefered factory lubricant.
A Green Chemistry breakthrough, United Bio Lube's complete line of Bio Hydraulic Fluids are formulated with patented Stabilized chemistry that effectively inhibits the breakdown of High Oleic Base Stocks (HOBS).
Oxidation Inhibitors reduce the quantity of oxygen reacting with HOBS by forming inactive soluble compounds that bond to the lubricant receptors in place of oxygen. Oxidation Inhibitors also work by passivating metal-bearing surfaces to retard the oxidation rate.
AP NOTE: Contrary to the powerful Anti-Oxidation properties of Stabilized&trade HOBS, petroleum based hydrocarbon molecules (Mineral Oils, Synthetics, Synthetic Blends) and Commercial Vegetable Oil formulations will react readily over time to incorporate oxygen atoms into their structure. This chemical reaction produces Gums, Acids, Sludge, and Varnish which foul or damage metal parts.
Anti-Foam Inhibitors
Anti-Foam Inhibitors are added to reduce foaming. In many applications, air or other gases may become entrained in oil. Unless these gases are released, a foam is produced.
Foaming can result in insufficient oil delivery to bearings, causing premature failure. Foam may also interfere with proper operation of equipment, such as lubricating pumps, and may result in false oil level readings. Under some circumstances, foam may overflow from oil reservoirs.
Anti-Leak
Anti-Leak additives prevent the leakage of fluid past seals and worn tolarances under high pressure conditions.
United Bio Lube's Bio Hydraulic Fluids (AL) provide Anti-Leak and/or Non-Drip performance. Anti-Leak fluids are formulated to provide Seal and Hose conditioning that
- Maintains Seal and Hose Flexibility
- Provides Positive Seal Seating
- Reduces Oil Leaks
- Extends Seal and Hose Life
- Prevents Blown, or Cracked, Hoses
Note: Leaks rank first in the list of most common problems with hydraulic equipment. Any component leaking in the system is increasing the heat load on the system, .i.e. A cylinder leaking high pressure fluid past its piston seal. Leaks cause the pressure in the system to drop. When pressure drops, heat is generated.
8.5 Renewable Bio Hydraulic Fluids
Stabilized High Oleic Base Stocks (HOBS)
United Bio Lube's Bio Hydraulic Fluids made from Stabilized High Oleic Base Stocks (HOBS) offer exceptional performance properties designed to improve efficiency and reliability in both production and maintenance.
Advanced Stabilized2 chemistry makes Bio Hydraulic Fluids made from HOBS suitable for the toughest applications in extreme operating environments.
There are clear performance differences measured between hydraulic fluid types formulated from Stablilized™ HOBS verses those formulated from traditional mineral oils, synthetics, or commercial vegetable oils.
The natural oily Fluid Film of these high viscosity, multi-grade products has proven in laboratory and field tests to outperform petroleum based fluids and commercial vegetable oil formulas in terms of Lubricity, Oxidation Stablility, Thermal Shear Stability, and Load Carrying Capacity.
Bio Hydraulic Fluids make obsolete the use of harmful petroleum based fluids.
Stabilized Bio Hydraulic Fluids vs. Petroleum & Commercial Vegetable Oils
Oxidation Stability clearly differentiates United Bio Lube's Bio Hydraulic Fluids from competive offering. In multiple 3rd Party comparative studies with competitive hydraulic fluids over time, United Bio Lube's Bio Hydraulic Fluids Outperformed Mineral Oils, Synthetics, Synthetic Blends, and Commercial Vegetable Oil formulations with superior ASTM D-2272 Rotary Bomb Oxidation Test (RBOT) time values (i.e. 600-613) and super low ASTM D-2893 Total Acid Number (TAN) values (i.e. 0.28 - 0.43).
The Bar Chart below shows the results of independent 3rd party Oxidation Testing performed on the 100% biodegradable Bio Ultimax™ AW Hydraulic Fluids 1000 and 2000. This testing clearly demonstrates that Ultimax™ 1000 and 2000 fluids are superior when compared to other leading commercial hydraulic fluids.
Testing data includes comparative results with all different types of hydraulic fluids, including:
- Ultimately Biodegradable and Biobased
- Readily Biodegradable and Petroleum-based
- Mineral Oil
- Synthetic Ester
- Synthetic Ester and Mineral Oil Blends
Through rigorous and demanding field testing, Bio Ultimax™ AW 1000 and 2000 Hydraulic Fluids have proven to outperform leading brands, including:
- Petroleum-based Mineral Oil Hydraulic Fluids
- Commercial Biobased Hydraulic Fluids
- Blended Biobased (Sunflower)/30% Synthetic Polyolester (Trimethylol Propane Oleate)
- Full Synthetic Polyolester based Hydraulic Fluids
ASTM D-2272 Rotary Bomb Oxidation Test (RBOT)
The Rotary Bomb Oxidation Test (RBOT) is a rapid method of comparing the oxidation life of
lubricants in similar formulations. It is used to evaluate the oxidation characteristics of turbine, hydraulic, transformer and gear oils. The results are reported as
the number of minutes to a 25 psi loss. The longer the time, the greater the stability of the fluid.
Bio Ultimax™ AW 1000 and Bio Ultimax™ AW 2000 technology outperforms all the other hydraulic fluids with a greater amount of time measured during RBOT testing.
AP NOTE: Full Synthetic Polyolester based hydraulic fluid is considered and promoted in the industry as a very stable formulation.
AP NOTE: 3rd party testing also shows that the Synthetic Polyolester based hydraulic fluid decreases in Viscosity before it starts to
increase in Viscosity. This is commonly seen in synthetic polyolester based formulas because of the chemical reactions during high temperature oxidation tests.
Superior Total Acid Number (TAN)
Hydraulic system and pump manufactures have reported acidic attack of internal metal components when hydraulic fluids reach TAN increase of 2.0 in real life hydraulic equipment applications.
Table 8.1 compares United Bio Lube's Bio Ultimax™ AW 1000 and 2000 Hydraulic Fluids to competitive petroleum and commercial vegetable oil based hydraulic fluids. Notice how both Bio Ultimax™ AW 1000 and 2000 Hydraulic Fluids demonstrate superior Oxidation Stability with the lowest TAN values.
Table 8.2 shows independent Oxidation Tests performed on the Bio Ultimax™ AW 1000 and 2000 Bio Hydraulic Fluids compared to competitive commercial hydraulic fluids. Notice how both Bio Ultimax™ AW 1000 and 2000 Hydraulic Fluids demonstrate superior Oxidation Stability with the lowest TAN values.
AP NOTE: Use of the term "Bio" in Commercial Polyolester Bio Hydraulic Fluid is intended to indicated some degree of Biodegradability, not that the product is Biobased, or Vegetable Oil based. Most Commercial "Bio" Hydraulic Fluid are made from Non-Renewable Synthetic Polyolesters. Traditionally, this type of safer environmental fluid is know in industry as an Environmentally Acceptable (EA) fluid, as opposed to a Biobased fluid.
See Chapter 13.3 Environmentally Acceptable (EA) Lubricants for a more complete discription of EA fluids.
8.6 Fluid and System Compatibility
Elastomer Compatibility
United Bio Lube's Bio Hydraulic Fluids are compatible with hydraulic system materials and components designed to operate on mineral oil based and most synthetic based hydraulic fluids.
One of the most widely used elastomers in the industry for mineral oil based hydraulic systems is Buna-N Low Nitrile Rubber (NBR-L). United Bio Lube's Bio Hydraulic Fluids are fully compatible with Buna-N Low Nitrile Rubber and other commonly used Elastomers.
Bio Hydraulic Fluids can operate in Static, Mid-Dynamic, and Dynamic areas of hydraulic systems that contain the following materials:
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ISO 1629
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Description (Trade Names)
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NBR
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- Medium to High Nitrile Rubber (Buna N, > 30% Acrylonitrile)
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NBR-L
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- Low Nitrile Rubber (Buna N, < 30% Acrylonitrile)
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FPM
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- Fluoroelastomer (Viton)
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AU
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- Polyurethane (Adiprene, Millathane)
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PTFE
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- Polytetrafluoroethylene (Teflon)
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CR
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- Polychloroprene (Neoprene)
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Mineral Oil Based Fluid Compatibility
Bio Hydraulic Fluids have been tested and have shown to be compatible with Mineral Oil based and most Synthetic based fluids.
Conversion procedures are much easier with Bio Hydraulic Fluids. No engineering design changes are necessary. Bio Hydraulic Fluids are compatible with the same filters, seals, hoses and accumulator bladders.
Bio Hydraulic Fluids have been designed to directly replace mineral oil based hydraulic fluids and improve the performance of the overall hydraulic system operation.
To convert a system, simply drain and recharge. Most of the fluid can be removed by draining the reservoir and lines. Flushing is not necessary for compatibility, but if you choose to flush, only use Bio Hydraulic Fluids as a flushing fluid.
Note: For proper biodegradability, at least 90% of the mineral oil based fluid should be removed from the system.
Bio Hydraulic Fluids may also be used as a top fill (with compatible fluids) until the existing fluid is converted in the maintenance schedule.
Synthetic Polyalphaolefins Based Fluid Compatibility
Bio Hydraulic Fluids have been designed to directly replace synthetic Polyalphaolefins (PAOs) and Semi-Synthetic PAO and mineral oil blends.
Bio Hydraulic Fluids are fully compatible with synthetic Polyalphaolefins (PAOs) and Semi-Synthetic PAO and mineral oil blends. These are the most widely used synthetic lubricants in the world lubricant market and generally are formulated to meet the same hydraulic systems compatibility requirements as mineral oil based fluids.
Converting a system would require the same procedure as mineral oil based above.
Synthetic Esters
Bio Hydraulic Fluids are highly compatible with systems designed to use Synthetic Esters.
Bio Hydraulic Fluids are compatible with most Synthetic Esters based fluids and depending on selection of esters they may be considered biodegradable. Renewable Lubricant, Inc.'s compatibility studies show Polyolesters and Diesters to be very compatible, however there can be compatibility problems when blending some complex ester fluids as shown in Renewable Lubricant, Inc.'s studies.
Note: Most synthetic ester based fluids have excessive seal swell on Butyl and Low Nitrile Rubber (NBR-L) and because of this, chemically resistant seals and components (NBR medium to high Nitrile, FPM, and PTFE) are recommended.
Phosphate Esters
Bio Hydraulic Fluids are compatible with some, but not all Phosphate Ester fluids. Testing is recommended before conversion. Seal compatibility should also be considered because Butyl rubber is the most compatible elastomer with Phosphate Esters.
Note: Butyl rubber has poor compatibility with mineral oils.
Water Glycol (HFC) and Invert Emulsions (HFB)
Bio Hydraulic Fluids are NOT compatible with water based fluids.
These fluids must be removed from the system by draining the reservoir and lines. Remove residual fluid by circulating and draining. Refill with Bio Hydraulic Fluid. Flush and repeat flushing until the residual is less than 1% of the system volume.
Standard practice for flush and purification of hydraulic systems may be found in ASTM D 4174-89.
8.7 Non-Renewable Types of Hydraulic Fluids
(1) Petroleum-based
Petroleum-based fluids are the most commonly used stock for hydraulic applications where there is no danger of fire, no possibility of leakage that may cause contamination of other products, no wide temperature fluctuations, and no environmental impact.
Non-Renewable, Non-Sustainable, Non-Biodegradable petroleum based hydraulic fluids include: Mineral Oils, Synthetic Polyalphaolefins (PAOs), Synthetic Esters, and Semi-Synthetic PAO/Mineral Oil blends.
(2) Environmentally Acceptable (EA)
The requirements for biodegradable fluids are discussed in Chapter 13.3 Environmentally Acceptable (EA) Lubricants.
Although EA fluids are Readily Biodegradable, they are still made from Non-Renewable, Non-Sustainable petroleum base oils.
(3) Fire Resistant (FR)
In applications where fire hazards or environmental pollution are a concern, water-based or aqueous fluids offer distinct advantages. The fluids consist of Water-Glycols and Water-in-Oil fluids with emulsifiers, stabilizers, and additives.
Water-Glycol
Water-Glycol fluids contain from 35 to 60 percent water to provide the fire resistance, plus a glycol antifreeze such as ethylene, diethylene, or propylene which is nontoxic and biodegradable, and a thickener such as polyglycol to provide the required viscosity.
Water-Oil Emulsions
Oil-in-Water
These fluids consist of very small oil droplets dispersed in a continuous water phase. These fluids have low viscosities, excellent fire-resistance, and good cooling capability due to the large proportion of water. Additives must be used to improve their inherently poor lubricity and to protect against rust.
Water-in-Oil
The water content of water-in-oil fluids may be approximately 40 percent. These fluids consist of very small water droplets dispersed in a continuous oil phase.
Synthetic Fire-Resistant Fluids
Three types of synthetic fire-resistant fluids are manufactured:
- Phosphate Esters
- Chlorinated (Halogenated) Hydrocarbons
- Synthetic Base (a mixture of these two)
8.8 Cleanliness Requirements
Due to the very small clearances and critical nature of hydraulic systems, proper maintenance and cleanliness of these systems is extremely important.
Bio Ultimax™ AW Series 1000 and 2000 Bio Hydraulic Fluids provide an exceptional level of system cleanliness that works to keep components in like-new condition.
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