Fluids

Fluids-- Objectives1. 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 ContainmentContaminant Containment Dispersant Corrosion Inhibitor Detergent Rust Inhibitor

Heat RemovalHeat Removal Oxidation Inhibitor

Friction ReductionFriction Reduction Friction Modifier VI Improver

TYPES OF CRUDE BASE ParafinicParafinic

Naturally Higher VI Higher Pour Point More Stable

NaphthenicNaphthenic 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 Oxidation

Rust

Defoamer

Antiwear

ADDITIVEZinc Dithiophosphate

Metal Sulfonates

Silicone

Zinc Dithiophosphate

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 Higher horsepower

Higher sump temp.

All-weather fluid

New friction materials

Finer filters

NEED Increased gear wear

protection More thermally stable

fluid Lower viscosity fluid

and better low temperature fluidity

More brake noise reduction and PTO clutch capacity

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?