presenting a sound knowledge about HYDAULIC ACCUMULATOR

1. SEMINAR ON
SUBMITTED
BY
VIKAS GUPTA
EN-VI (B)

2. OVERVIEW
 Introduction
 History
 Types of Hydraulic Accumulator
 Functions of Accumulator
 Accumulator design consideration
 Application
 Conclusion

3. INTRODUCTION
 A Hydraulic Accumulator is energy storage device.
 It is pressure storage reservoir in which a non-
compressible hydraulic fluid is held under pressure by an
external source.
 The external source used can be a spring, a raised
weight, or a compressed gas.
 The main reasons that an accumulator is used in a
hydraulic system, is that the pump doesn’t need to be so
large to cope with extremes of demand and supply circuit
can respond quickly to any temporary demand and to
smooth pulsation.

4. HISTORY
 First Hydraulic accumulator was made
by William Armstrong in 1846 built a
crane powered by water of town mains
at Newcastle, United Kingdom.
 Later 1852 ,Armstrong used Grimsby
Dock Tower for the constant pressure
for cranes, lock gates and sluices.
 Grimsby Dock Tower is hydraulic
accumulator is used for the purpose of
containing a 30,000UK gallon (136 m3)
hydraulic wrought iron reservoir at a
height of 300feet (91 m) to provide
power for lock gates and cranes of
Grimsby Dock.

5. 1. Tower type accumulator
2. Raised weight accumulator
3. Compressed-gas accumulator
4. Spring accumulator
TYPES OF HYDRAULIC
ACCULUMATOR

6. 1. TOWER TYPE ACCUMULATOR
 The first accumulators for
Armstrong’s hydraulic dock
machinery were simple raised water
tower.
 It uses hydraulic head
 It delivers constant pressure to the
output
LONDON TOWER BRIDGE

7. 2. RAISED WEIGHT ACCUMULATOR
 A raised weight accumulator consists
of a vertical cylinder containing fluid
to the hydraulic line.
 The cylinder is closed by a piston on
which a series of weights are placed
that exert a downward force on the
piston and thereby energizes the fluid
in the cylinder.
 Gravity acts on the weight to
pressurize the hydraulic system
fluid, thus storing energy.

8. ADVANTGES :
 Used to meet heavy industrial
requirements.
 Extremely high capacity at low cost.
 Rugged and durable construction.
LIMITATIONS :
 Extremely bulky and heavy.
 Problem in sealing.
Hydraulic engine
house, Bristol Harbor.

9. 3. COMPRESSED GAS ACCUMULATOR
 It is widely used accumulator in present scenario.
 It is popularly known as “hydro-pneumatic
accumulator”. It apply force to the liquid by using a
compressed gas that acts as the spring.
 It uses inert gas (nitrogen) under pressure that provides
the compressive force on fluid.
 Oxygen is not used because oxygen and oil can form an
explosive mixture when combined under pressure
 As the volume of the compressed gas changes the
pressure of the gas, and pressure of the fluid, changes
inversely.

10. 4. Spring type accumulator
 It uses the energy stored in springs to create a constant
force .
 The load characteristics of a spring are such that the
energy storage depends on the force required to
compress s spring.
 The free (uncompressed) length of a spring represents
zero energy storage.
 As liquid under pressure enters the cylinder, causing a
spring to compress, the pressure on the liquid will rise
because of the increased loading required to compress
the spring.

11. HYDARULIC SYMBOLS

12. FUNCTIONS : Where are accumulators used?
Accumulators can be applied creatively in any number of
situations, including:
 Shock or pulsation dampening: An accumulator can be used to
cushion the pressure spike from sudden valve closure, the
pulsation from pumps or the load reaction from sudden
movement of parts connected to hydraulic cylinders.
 Leakage compensation: An accumulator can be used to
maintain pressure and make-up for lost fluid due to internal
leakage of system components including cylinders and valves.
 Thermal expansion: An accumulator can absorb the pressure
differences caused by temperature variations in a closed hydraulic
system.

13.  Energy conservation
 Improved response times: An accumulator (bladder type) has virtually
instantaneous response time that can provide fluid very quickly to fast-acting
valves such as servos and proportional to improve their effectiveness
Discharge valve, electric
(optional)
Accumulator
P-port
Gauge
portShut-off valve
Manifold Block
Pressure-
relief
valve
Discharge,
manual
Adapter
fitting, Flange

14. ACCUMULATOR DESIGN CONSIDERATION :
(What must I know to size and select an accumulator?)
Accumulator type
Accumulator volume
Nominal hydraulic system pressure
Minimum and Maximum hydraulic system pressure
Pre-charge pressure
Required flow rate
Output volume capacity
Recharge time
Response time
Fluid type

15. APPLICATIONS
Accumulators are devices used to store fluid power to do the
following:
Agricultural Machinery & Equipment.
Forestry Equipment.
Oil Field & Offshore.
Machine Tools and Off- Road Equipment.
Mining Machinery & Equipment.
Construction Equipment.
Suspension in vehicles.

16. CONCLUSION
So what are the benefits of using accumulators?
 Lower installed system costs, accumulator assisted
hydraulics can reduce the size of the pump and electric
motor which results in a smaller amount of oil used, a
smaller reservoir and reduced equipment costs.
 Less leakage and maintenance costs, the ability to reduce
system shocks will prolong component life, reduce leakage
from pipe joints and minimize hydraulic system
maintenance costs.
 Improved performance, low inertia bladder accumulators
can provide instantaneous response time to meet peak flow
requirements. They can also help to achieve constant
pressure in systems using variable displacement pumps for
improved productivity and quality.

17.  Reduced noise levels, reduced pump and motor size
couple with system shock absorption overall machine
sound levels and results in higher operator
productivity.
 Flexible design approaches. A wide range of
accumulator types and sizes, including accessory
items, provides a versatile and easy to apply design
approach.
 Reduced energy costs, cost savings of up to 33% are
achievable in high performance industrial machinery
using accumulators.