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Fluids Fluids-- Objectives 1. List four functions of the fluid. 2. List five qualities of a good fluid 3. Explain the difference in two types of crude. 4. Define terms associated with fluids. Fluids– Objectives 5. 5. Explain the affects of high and low viscosity fluids on a system 6. 6. List appropriate practices for the management of stored fluids. 7. 7. List appropriate practices for the management of fluids in use. Four Basic Functions of a Fluid • Transmit power- must be a flow • Lubrication • Sealing • Cooling LUBRICANT FUNCTIONS Contaminant Containment Dispersant Corrosion Inhibitor Detergent Rust Inhibitor Heat Removal Oxidation Inhibitor Friction Reduction FrictionModifier VI Improver TYPES OF CRUDE BASE Parafinic Naturally Higher VI Higher Pour Point More Stable Naphthenic Low VI Low Pour Point Less Stable TYPES OF HYDRAULIC FLUIDS – Mineral Oil Based - Antiwear and R&O - R&O - Ashless – Synthetic Based - Fire Resistant Phosphate Ester – Water Based - Water-in-Oil (Invert Emulsion) - Water Glycol - Oil-in-Water Quality of a fluid The quality of a fluid/petroleum oil will depend on the: Type of crude used Degree or extent of refining and method of refining Additives used To be a quality Hydraulic fluid it must: • Prevent rust • Prevention formation of sludge, and gum varnish • Be Foam resistant • Maintain its own stability and thereby reduce fluid replacement cost To be a quality fluid it must…2 • Remain stable over a variety of temps. • Separate out water • Be compatible with seals and gaskets • Conform to special industry standards • *Additives 40% + CHOOSING A HYDRAULIC FLUID – Regular or Fire Resistant – Viscosity – Viscosity Index – Pour Point – Oxidation Stability – Rust Protection – Foaming and Air Release – Water Separation – Antiwear Properties Five properties of fluid Viscosity Pour Point Lubrication Oxidation Rust and corrosion Demulsibility ADDITIVES USED IN HYDRAULIC OILS FUNCTION ADDITIVE Oxidation Zinc Dithiophosphate Metal Sulfonates Rust Silicone Defoamer Zinc Dithiophosphate Antiwear Properties of fluid: Viscosity The measure of a fluids resistance to flow; or an inverse measure of fluidity. Low viscosity (thin) runs fast, high viscosity (thick) runs slow. Viscosity Index (VI) An arbitrary scale using an empirical formula to indicate the effect of temperature changes on the viscosity changes in lubricating oils; shown by comparing Pennsylvania oil that measures 100 on the scale to an asphaltic oil that measures zero. Source: Harcourt Dictionary A measure of change in thickness over a temperature range. Low number (0-20) means the thickness changes a lot with temperature change, While a High number (70-100) changes a little. Affect of viscosity on system • High viscosity fluid (thicker) • Increases resistance to pressure. • Increases power output due to friction • Increases temp due to friction • Increases sluggishness or slow to operate • Delivers less force at end due to friction • Greater difficulty in separating air from fluid in reservoir Affect viscosity on system, cont.. • Low viscosity fluid (thinner) • More leaks • More wear on even seizure under heavy loads due to break down of oil film. • Pump efficiency may decrease, causing slower operation of the actuator • Less efficient, causes higher temps VI Improvers (VII) Additives that prevent changes in viscosity over a range of temperatures Viscometer Device for measuring the viscosity of a fluid. Used to establish ASE numbers Properties of fluid: Pour Point The lowest temperature at which a fluid will flow. Only important in cold temps. PP should be 20 degrees F below the lowest temp expected Society of Automotive Engineers (SAE) Winter grad oils and summer oils SAE 10W 30 Winter oils—have a W after the number - -Number represents the 32 degrees F Summer oils– no W, 212 F 10W– 3500 cPa – 4 F degree The range 45 sus to 4000 sus is recommended, 150 is recommended for industry Hydraulic fluid is identified as SUS or Centisoke (millimeters squared/sec) A temperature may also be given Properties of fluid: Lubricating ability EP- Extreme Pressure Some fluids have EP additives to help prevent wear. Generally used where there is high pressure and high heat. Properties of fluid: Oxidation Resistance A chemical reaction, first state reaction develops gums, sludge, and varnish Some oxidation by-products are acids Some cause wear, some cause a breakdown of seal, hoses, metal which then enter the system as a contaminate. Heat, pressure, water, and metal to metal contact, contaminants, and agitation of fluid all make oxidation more likely. Properties of fluid: Rust & Corrosion Prevention Most common is rust (iron or steel and oxygen) Additives are used that plate the metal surface to prevent chemical attack. Properties of fluid: Demulsibility The ability of a fluid to separate-out water Small quantities of water will not cause a serious problem. However, too much will cause fluid to breakdown, valves to stick, and components to wear to quickly. Opposite of Demulsibility (separate out) is Emulsibility (incorporate into). Some additives promote emulsibility which prevents moisture from settling in on place and thereby causing rust and breaking the antirust film on the metal Emulsion is a mixture of water and oil under pressure. Enemies of fluid/systems Extremes in heat and cold For every 20 Degrees over 180 you half the fluid life oxidized is like road tar. Examples: 200 degree operating temp of a 3000 hour fluid = 1500 220 degree operating temp of a 2000 hour fluid = 500 Enemies of fluid/systems, cont.. Examples, cont.. 240 degree operating temp of a 2000 hour fluid = 250 220 degree operating temp of a 3000 hour fluid = 750 200 degree operating temp of a 2000 hour fluid = 1000 240 degree operating temp of a 3000 hour fluid = 375 260 degree operating temp of a 2000 hour fluid = 260 degree operating temp of a 3000 hour fluid = Enemies of fluid/systems, cont.. Dust or dirt Air—Foaming– Compressed or otherwise, compressed can enter fluid Turbulence promotes mixing of the fluid with air Air may enter through leaks. Which side of the pump will air enter. Enemies of fluid/systems, cont… Water or moisture How do you know if you have water in the fluid? Heat a piece of metal and if it patters when oil drops on it then it has water. Where does it enter the system? What happens when you drop water in a pan when you are frying something Enemies of fluid/systems, cont… Oxygen- oxidation--- heat (each 18 deg rise in temp doubles oxidation) and air cause organic acids to form from the chemical reaction. Rust and corrosion- rust adds thickness- corrosion eats away, related to oxidation TRACTOR INDUSTRY TRENDS TREND NEED Higher horsepower Increased gear wear protection Higher sump temp. More thermally stable fluid Lower viscosity fluid All-weather fluid and better low temperature fluidity New friction materials More brake noise reduction and PTO clutch capacity Finer filters Better fluid filterability Fluid Maintenance Changing the fluid and/or flushing the system cost money therefore it is important to keep clean Store drums on their side and under roof Before opening drum clean the top and cap thoroughly Use only clean hoses and containers to transfer the fluid. Some people use a transfer pump with filter. Use a 200 mesh screen in the reservoir Keep hoses and surfaces clean, they cause dirt to collect. Follow directions of the maker of fluid or machinery for regular drainage. In use prevention Prevent contamination by keeping the system tight Use proper air and fluid filteration Replace fluid at regular intervals to prevent it from breaking down. Follow the maker directions. Check fluid before the expected time to change. Keep the fluid at the recommended level. This prevents condensation on wall of reservoirs Repair all leaks immediately Change/Check filters regularly Review Time….. Crude oil yields two types of oils, what are they? ISO stands for what? A good viscosity index is ______ number and above. Detergent in oil will cause oils to _________. What two types of pumps require greater lubrication? Fluids that are flame resistance usually have one of two base liquids. What are they?
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