عضویت 
ورود اعضا
راهنمای خرید
e33010 pages
Piston Accumulators
Fluids are practically incompressible and
cannot therefore store pressure energy.
The compressibility of a gas (nitrogen)
is utilised in hydraulic accumulators for
storing fluids. HYDAC piston accumulators
are based on this principle.
A piston accumulator consists of a fluid
section and a gas section with the piston
acting as the gas-proof screen.
The gas section is pre-charged with
nitrogen.
The fluid section is connected to the
hydraulic circuit so that the piston
accumulator draws in fluid when the
pressure increases and the gas is
compressed.
When the pressure drops, the compressed
gas expands and forces the stored fluid
into the circuit.
1.2.t Design
gas valve
end cap safety device
end cap
piston
sealing system
cylinder
external seal
end cap safety device
fluid connection
HYDAC piston accumulators consist of:
zzA cylinder with very finely machined
internal surface.
zzEnd caps on the gas side and the oil
side. Sealed with O-rings.
zzA floating steel or aluminium piston
which can easily be accelerated due to
its low weight.
zzA sealing system adapted to the
particular application.
The piston floats on two guide rings
which prevent metal-to-metal contact
between the piston and the accumulator
wall.
For use with certain aggressive or
corrosive fluids, the parts coming into
contact with the fluid can be nickel plated
for protection, or made entirely from
corrosion-resistant material.
Suitable materials are also available for
low temperature applications.
1.3.tSEALING SYSTEMS
Precise information about operating
conditions is required in order to select
the most appropriate sealing system.
Important criteria for this selection are, for
example:
zzDesign pressure,
zzEffective pressure differential,
zzSwitching frequency or cycles,
zzTemperature fluctuation,
zzOperating fluid,
zzCleanliness of fluid (micron rating of
filter),
zzMaintenance requirements.
The sealing systems differ according to
the type of piston used, each of which has
its own type and arrangement of seals.
The following elastomer sealing materials
are available, depending on the operating
conditions:
zzNBR (acrylonitrile butadiene rubber,
perbunan),
zzFKM (fluoro rubber, Viton®),
zzPUR (polyurethane).
E 3.301.16/03.12
1.tDescription
1.1.tFunction
39
"
