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.
6.
7.
5. Explain the affects of high and
low viscosity fluids on a system
6. List appropriate practices for
the management of stored fluids.
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
 Friction
Modifier
 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
 Oxidation
 Rust
ADDITIVE
Zinc Dithiophosphate
Metal Sulfonates
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
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?