Types Of Hydraulic Fluids (Type 2 and 3)

Petroleum Based Fluids(Type 2)
These are the commonly used fluids for hydraulic applications where there is no danger of fire,no possibility of leakage that may cause contamination of  other products,no wide temperature fluctuation and no environmental impact.
Advantages
Excellent lubricity,reasonable cost,non-corrosive
Disadvantages
-Tendency to oxidize rapidly
-Not fire resistance
Synthetic Based Fluids(Type 3)
There are 3 types of synthetic based fluids.

1. Phosphate esters
2. Chlorinated hydro carbons
3. It is a synthetic base mixture of phosphate esters and chlorinated hydro carbons and do not contain avatar or volatile materials,and they provide satisfactory operation at higher temperatures.these are suitable for high pressure applications.so specific gravity of these type of fluids is high.

Halogenated hydro carbons fluids are inert odorless non-fameble,non-corrosive and have low torcicity.

Types Of Hydraulic Fluids (Type 1)

Water And Water Based Fluids

• Water

It is least expensive hydraulic fluids.It is treated with some chemicals before used in a fluid power system.

1. Advantages
   1) Inexpensive
   2) Readily available
   3) Fire resistance

1. Disadvantages
   1) No lubricity
   2) 

Corrosive

• Water Based Fluids

Under this classification,mainly there are two types

1) Water Glycol

2) Water oil 

emulsions

1. Water Glycoles
   In water glycol combination,35-60% water to provide the fire resistance,plus a glycol anti frees like ethylene, ethylene,propelene which is non-toxic and bio-degradable.and it provide more viscosity.the operating temperature for water glycol fluids should be maintained below 50 degree Celsius to prevent evaporation and deterioration of the fluid.
   Viscosity,PH,water hardness monitoring are very important in water glycol systems.
   Advantages
   Good fire resistance,inexpensive.
   Disadvantages
   -Not good for high loads
   -Poor corrosion resistance.
2. Water Oil Emulsions
   -Oil in water
   In this emulsion very small oil droplets dispersed in a continues water phase.these fluids have low viscosity, excellent fire resistant and good cooling capacity and some additives are used to improve lubricity and to protect against rest.
   -Water in oil
   In thisemultion,water is approximately 40%the major condunt is oil.In this combination very small water droplets dispersed in a continues phase of oil.
   The oil phase provides good to exellent lubricity  while the water condent provides the cooling capability and fire resistance.
   Advantages
   -Good for fire resistance
   -Inexpensive
   Disadvantages
   It should be properly monitored to ensure that the proper viscosity is maintained.

Fluid Power

Fluid Power
Fluid power is a technology that deals with the generation,control,and transmission of power using pressurized fluids.
Fluid power includes hydraulics and pneumatics.
Hydraulics->Which involves liquid.
Pneumatics->Which involves gases.
Basic Laws Of Fluid Power

1. Pascal's Law
   Pascal's Law states that when a pressure exerted on a confined fluid,pressure is transmitted in all directions equal force in equal area.
2. Bernaulli's Law
   For a perfect in-compressible liquid,flow along a stream line,the total energy of particle same while the particle moves from one point to another point.

Application Of Fluid Power

1. Operation and control of machine tools
2. Farm machining
3. Construction machining
4. Mining machining
5. Locomotives
6. Ships
7. Airplanes
8. Space craft operations
9. Working of hydraulic shaper,hydraulic lifts,hydraulic jack,hydraulic ram,hydraulic crain,hydraulic press

Advantages Of Fluid Power

1. High pressure can be operated
2. Transmission of motion is less noisy
3. Vibration and shock load can be reduced
4. Maintenance is simple and less costy
5. It is cheaper than pneumatic system and mechanical system.
6. The parts of the machine can be automatically lubricated by the liquid itself
7. It does not require complicated mechanisms involving link motions by gears,rack and pinion,etc.
8. Accurate speeds are possible.
9. No explosion of fire and wear and tear.

Power Of Hydraulic Fluids

1. Power transmission
2. Lubrication
3. Cooling  

Hydraulic Gradient Line And Total Energy Line

Hydraulic Gradient Line And Total Energy Line

Hydraulic Gradient Line And Total Energy Line are the graphical representation for the longitudinal variation in piezometric head and total head.
Consider two points 1 and 2 in a pipe line having 'l' meters apart with the reference to this potential datum line,z1,p1/w and v1^2/2g represent datum head,pressure head,velocity head at section 1. similarly the corresponding values at 2.
The some of potential and pressure head.ie,[z+p/w] at any point is called the piezometric head.if a line joining the piezometric levels at varies points,the lines so obtain is called hydraulic gradient line (HGL)
The some of potential head,pressure head and velocity head is known as total head.
If a line joining the total heads at various points,the line so obtained is called total energy gradient line.

Flow Through Pipes And Nozzles

PIPE
Pipe is a closed conduit or circular cross section carrying fluid under pressure.
Loss Of Head Or Energy In Pipes
When the fluid flows through the pipe experiences some resistance to motion between the pipe inner surfaces and fluid.
The effect of this resistance to motion reduces the velocity of fluid and finally the head of fluid.
The loses of energy is classified as:

1. Major Losses
   This losses due to the friction and is called as loss of head due to friction.
   (a) Darcy-Weisbach formula for loss of head in pipes.
   (b) Chezy's formula for loss of head in pipe.
2. Minor or Secondary Losses
   (a) Loss of head due to inlet.
   (b) Loss of head due to sudden enlargement.
   (c)  Loss of head due to sudden contraction.
   (d)  Loss of head due to sudden obstruction.
   (e)  Loss of head due to pipe fitting.
   (f)  Loss of head due to outlet.

Notches

Notch is defined an opening provided in the side of a tank.The upstream liquid level below the top edge of the opening.The bottom edge over which the liquid flows is called the sill or crust of the notch.
The sheet of water flowing over the bottom edge of the notch is called nappe or vein.
The height of water above the sill of the notch is called the head of the notch.
Classification/Types of notches

1. According to the shape of the opening of the notch.
   The notches are classified as rectangular notch,triangular notch,trapezoidal notch,stepped notch.
2. According to the effect of side of opening
   The notches are classified as:
   (a) Notch with end contraction (If the notch width or length is less than the width of the channel it is known as notch with end contraction)
   (b) Notch without end contraction. (Notch width or length extends over the full width of the channel in which it based known as notches without end contraction)

Hydraulic Coefficients

HYDRAULIC COEFFICIENTS
Coefficient Of Contraction
Coefficient of contraction is the ratio between area of jet at vena contracta to the area of the orifice.it is denoted by Cc
Cc=Ac/a
Where,
Ac=>Area of the jet at vena contracta.
a=>Area of the orifice.
Value of Cc varies from 0.61-0.69
Coefficient Of Velocity
Coefficient of velocity(Cv) is the ratio of actual velocity of the jet at vena contracta to the theoretical velocity of jet.
Let,av=actual velocity of jet at the vena contracta
Vtheoretical is the theoretical velocity of jet at vena contracta=√2gH
Cv=V/Vtheo=V/√2gH
Value of Cv varies from 0.95-0.9
Coefficient Of Discharge
Coefficient of discharge(Cd) is defined as the ratio between actual discharge to the theoretical discharge.
ie,Qact/Qtheo
Where,
Qa=>Actual discharge through the orifice
Qt=>Theoretical discharge through the orifice.
Value of Cd varies from 0.60-0.64