The document outlines the essential properties and requirements for hydraulic fluids, emphasizing their primary tasks such as power transmission, lubrication, and heat transport. Key characteristics include good lubrication, stable viscosity, fire resistance, and environmental safety, while also highlighting the need for effective heat dissipation and prevention of foaming. It discusses the impact of hydraulic fluids on system efficiency and protection against wear and corrosion, emphasizing the importance of selecting appropriate fluids for various applications.

1. Mohammad Azam Khan
HYDRAULIC FLUID
&
PROPERTIES
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2. Mohammad Azam Khan
JOB PERFORM
BY THE HYDRAULIC OIL
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• They have the following primarytasks:
– Power transmission (pressure and motion transmission)
– Signal transmission for control
• Secondary tasks:
– Lubrication of rotating and translating components to avoid friction and wear
– Heat transport, away from the location of heat generation, usually into the
reservoir
– Transport of particles to the filter
– Protection of surfaces from chemical attack, especially corrosion

3. Mohammad Azam Khan
HYDRAULIC FLUIDS
REQUIREMENTS
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• Functional
– Good lubrication characteristics
– Viscosity should not depend strongly on temperature and pressure
– Good heat conductivity
– Low heat expansion coefficient
– Large elasticity modulus
• Economic
– Low price
– Slow ageing and thermal and chemical stability ⇒ long life cycle

4. Mohammad Azam Khan
HYDRAULIC FLUIDS
REQUIREMENTS
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• Safety
– High flash point or in certain cases not inflammable at all
– Chemically neutral (not aggressive at all against all materials it touches)
– Low air dissolving capability, not inclined to foam formation
• Environmental friendliness
– No environmental harm
– No toxic effect

5. Mohammad Azam Khan
PROPERTIES OF
HYDRAULIC FLUID.
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• Good Lubricity
• Stable Viscosity Characteristics
• Good Heat Dissipation
• Flash Point
• Low FoamingTendency
• Fire Resistant
• Prevent Rust Formation
• Non-toxic, Easy to handle & Available

6. Mohammad Azam Khan 6
• The component in a hydraulic system contain many surface which are in
close contact and which move in relationto each other. The hydraulic
fluid must separate and lubricate such surfaces.
• Protectionagainst wear is a principal reason for selectinga fluidhaving
good lubricationcharacteristicsas a hydraulic medium.
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GOOD LUBRICITY

7. Mohammad Azam Khan
GOOD HEAT DISSIPATION
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• An important requirementof the fluid is to carry heat away from the
working parts.
• Pressure drops, mechanical friction,fluidfriction,leakages, all
generate heat.
• The fluid must carry the generated heat away and readily dissipate it to
the atmosphere or coolers.
• Therefore high thermal conductivityand high specific heat
values are desirable in the fluid chosen.
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8. Mohammad Azam Khan
FLASH POINT
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• The flash point of a hydraulic oil is defined as the temperature at which flashes
will be generated when oil is brought into contact with any heated matter,e.g., a
heat stick.
• Low flash point oils are not use as Hydraulic Oil.
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9. Mohammad Azam Khan
LOW FOAMING
TENDENCY
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• Foam results from air or other gases becoming entrainedin the hydraulic
fluid.Air enters a hydraulic system through the reservoir or through air
leaks within the system.
• A hydraulic fluidunder high pressure can containa large volume of
dissolvedor dispersedair bubbles. When this fluidis depressurized,the air
bubbles expand and produce foam. Because of its compressibilityand poor
lubricatingproperties, foam can seriouslyaffect the operation and
lubricationof machinery.
• Proper foam inhibitors modifythe surface tension on air bubbles so they
more easily break up.

10. Mohammad Azam Khan
FIRE RESISTANT
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• Fire resistance is one of the properties that is optional in a good usable
hydraulic fluid.
• The commonly used hydraulic liquidare petroleum derivative, and
consequentlythey burn vigorously once they pass the point.
• For critical application,artificialor synthetic hydraulic fluid are used
which have high fire resistances.Various grades of fluids with high water
content are also available now a days for oil hydraulic system.
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11. Mohammad Azam Khan
STABLE VISCOSITY
CHARACTERISTICS
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• Viscosityis a measure of a hydraulic fluid's resistance to flow. It is a
hydraulic fluid's most important characteristic and has a significant impact
on the operation of the system.
• When a hydraulic oil is too thin (low viscosity),it does not seal
sufficiently.
This leads to leakage and wear of parts.
When a hydraulic oil is too thick(high viscosity),the fluid will be more difficult
to pump throughthe system and may reduce operating efficiency.
All hydraulic fluids must be able to retain
optimum viscosity during operationin cold or
hot temperatures,inorder to consistentlyand
effectivelytransmitpower

12. Mohammad Azam Khan
PREVENT RUST FORMATION
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• In many systems,water can enter as condensationor contamination,and
mix with the hydraulic oil. Water can cause rusting of hydraulic
components.
• In addition,water can react with some additives to form
chemical species which can be aggressive to yellow metals.
• Hydraulic oil formulations containrust and corrosion inhibitors which
prevent the interactionof water or other chemical species from attacking
metal surfaces.
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13. NON-TOXIC, EASY TO
HANDLE & AVAILABLE
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• These characteristics refer to the interactionof the fluidwith people
who repair,handle, use or pay for hydraulic system fluid.
• Obviously, it is desirable that the fluid be as simple to handle
and as available and cheap as possible.
Sanjay Humania[M.TeOil ch- Mechatronics]

14. Mohammad Azam Khan
FLUID POWER SYSTEMS
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