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CHAPTER 6.3 (ACCESSORIES) - Coggle Diagram
CHAPTER 6.3 (ACCESSORIES)
Accumulators
hydraulic accumulator is a pressure vessel used for storing fluid (Potential energy)
Function
To smooth out pressure surges
To provide emergency power sources
To meet peak demands of power
Types:
Weight loaded / Gravity type
Oldest design
Gravity force provides potential energy in the accumulator
Consist of a cylinder, piston and dead weight
Provide constant fluid pressure throughout full volume output regardless of rate and quantity output
Bulky in design
Gas loaded type
operates with Boyle's law of gases (constant temperature process, the pressure of gas varies inversely with its volume.
Two main categories
Separator type
Diaphragm
Advantage
Small weight-to-volume ratio
Disadvantage
Limited application
Piston type
Advantages
Ability to operate at high pressure
Ability to operate at high temperature
Disadvantages
Limited practical size
Piston and seal friction problem in low pressure system
Expensive to manufacture
Leakage occurs when used over long periods
Bladder type
Advantages
Secure sealing between the gas and oil chambers
Lightweight bladder provides quick response for pressure regulating, pump pulsation and shock dampening applications.
Non- separator type
More practical than weight and spring loaded
Spring loaded type
Similar to weight loaded, except piston is preloaded with a spring
Potential energy provided by compressed spring. Pressure exerted on fluid is not constant.
Not suitable for high cycle rates operation
Intensifiers
Pressure intensifiers
act as a booster to increase the fluid pressure available from the supply source.A cost saving measurement.
Example
Punch press system
Role of pressure intensifier
Eliminate the need for a high pressure/ low flow pump
Operation
high pressure output of intensifier closes the pilot check valve and pressurizes the blank end of cylinder to perform punching operation :
a pilot check valve is used instead of a regular check valve to permit retraction of the cylinder
when pressure in cylinder reaches the sequence valve pressure setting, intensifier starts operate
intensifier should be installed near the cylinder to keep high pressure lines as short as possible