Hydraulic Bladder Accumulators

203 Pages·06.17 MB·English

by  Merchant & Associates

Parker… BLADDER PRODUCTS HAcydcruamuulilca tor
your most complete source
Products
for Hydraulic Accumulators
and related products.
Parker’s Accumulator Products are Catalog HY10-1630/US
designed to optimize the performance
BLADDER PRODUCTS
of your hydraulic system, while adding
safeguards that prolong equipment life.
Reduced operating costs and savings
from less downtime and maintenance
are the benefits.
H
Parker Accumulators specifically… y
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• Provide an auxiliary power source by holding
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supplemental power to be used during peak periods. a
This allows the use of smaller pumps, motors, and Piston Accumulators Bladder Accumulators u
reservoirs reducing installation and operating costs. l
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• Protect hydraulic systems and circuit components from c
damage due to thermal expansion and contraction in a
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closed system.
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• Reduce costly damage to piping systems, fittings, and c
gauges by absorbing hydraulic line shocks. u
• Supply emergency fail-safe power to complete a work m
safety cycle in the event of a pump or electric power
u
failure.
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• Hold necessary high pressure for long periods of time
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while preventing oil overheating, reducing pump wear, o
and saving energy.
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P
Diaphragm Accumulators KleenVent Reservoir
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Isolators o
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u
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BLADDER PRODUCTS t
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Inline Pulse-Tone™ SurgeKushons
Shock Suppressors
Parker Hannifin Corporation Catalog HY10-1630/US
Hydraulic Accumulator Division 3M 5/06 DBH
10711 N. Second Street
Printed in U.S.A.
Rockford, IL 61115
BLADDER PRODUCTS
[phone]
Fax: [phone]
Web site: http://www.parker.com/accumulator
Parker Hannifin Corporation
6035 Parkland Blvd.
Parker… Cleveland, Ohio 44124-4141 Parker Hannifin Corporation
Telephone: [phone]
Your Best Source Fax: [phone]
www.parker.com
for Hydraulic
Accumulators!
About Parker Hannifin Corporation Parker’s Charter
Parker is the leading Parker Hannifin is a leading global motion-control To be a leading worldwide manufacturer of components
manufacturer of hydro- company dedicated to delivering premier customer and systems for the builders and users of durable goods.
pneumatic accumulators service. A Fortune 500 corporation listed on the New More specifically, we will design, market and manufac-
for industrial and mobile York Stock Exchange (PH), our components and ture products controlling motion, flow and pressure.
applications in North New products are designed utilizing the Modern machining centers ensure highest systems comprise over 1,400 product lines that We will achieve profitable growth through premier
America. With over 50 latest software technologies. quality accumulator parts. control motion in some 1,000 industrial and aero- customer service.
years experience and one space markets. Parker is the only manufacturer to
of the world’s broadest offer its customers a choice of hydraulic, pneumatic, Product Information
accumulator product and electromechanical motion-control solutions.
North American customers seeking product infor-
offerings, Parker has the Our Company has the largest distribution network in
mation, the location of a nearby distributor, or repair
products and application its field, with over 7,500 distributors serving nearly
services will receive prompt attention by calling the
expertise to be your best 400,000 customers worldwide. Parker Product Information Center at our toll-free
source for your next
number: 1-800-C-PARKER (1-800-272-7537). In Europe,
accumulator solution.
call 00800-C-PARKER-H (00800-2727-5374).
Parker’s capabilities
include:
The Aerospace Group is The Climate & Industrial
(cid:127) Expanded product line to
a leader in the development, Controls Group designs,
meet any application design, manufacture and ser- manufactures and markets
vicing of control systems and system-control and fluid-
(cid:127) In-house manufacturing components for aerospace and handling components and
capabilities related high-technology mar- systems to refrigeration, air-
kets, while achieving growth conditioning and industrial
(cid:127) Exclusive in-house through premier customer customers worldwide.
service.
bladder molding facility
Accumulator parts are manufactured in high-tech manufacturing cells.
(cid:127) ASME approved and CE
audited manufacturing
The Fluid Connectors The Seal Group designs,
plant Group designs, manu- manufactures and distributes
factures and markets rigid industrial and commercial
(cid:127) UL and FM approved
and flexible connectors, sealing devices and related
manufacturing plant and associated products products by providing
used in pneumatic and superior quality and total
(cid:127) Quick delivery response fluid systems. customer satisfaction.
(cid:127) National distribution
network with factory
trained sales
representatives The Hydraulics Group The Filtration Group
designs, produces and markets designs, manufactures and
(cid:127) Localized factory sales Large bore piston accumulators are State-of-the art assembly cells allow for fast
a full spectrum of hydraulic markets quality filtration
support machined on large capacity lathes. response to customer demands. components and systems and clarification products,
to builders and users of providing customers with
(cid:127) Application and industrial and mobile the best value, quality,
engineering support machinery and equipment. technical support, and
global availability.
(cid:127) Worldwide capabilities
(cid:127) ISO 9001 Certified
The Automation Group The Instrumentation
is a leading supplier of pneu- Group is a global leader
matic and electromechanical in the design, manufacture and
components and systems to distribution of high-quality
automation customers world- critical flow components for
wide. worldwide process instrumen-
tation, ultra-high-purity, medi-
cal and analytical applications.
Parker’s in-house designed pre-charge Every accumulator is cycle tested prior to
machine ensures proper pre-charge shipment.
regardless of ambient temperature.
Hydraulic Accumulators
Catalog HY10-1630/US
PCaognetents Introduction
0
0
Introduction ............................................................................................................................................................ 2 0
3
Certifications .......................................................................................................................................................... 3
n
Accumulator Selection Guide (Making the Right Choice) ............................................................................... 4-15 o 0
t 0
inPHorm™ Software............................................................................................................................................. 16 is 40
P
Application Data Sheet ........................................................................................................................................ 17
0
Piston Accumulators – A & B Series .............................................................................................................. 19-64 0
0
• Series 3000 Piston Accumulators and Gas Bottles (3000 PSI & 207 Bar Metric) ..............................................................22-39 5
(cid:127) Series 3000 Non-ASME (7” Bore) .....................................................................................................................................32-33
(cid:127) 2000 PSI (12” Bore) ..........................................................................................................................................................34-35 er
(cid:127) Series 4000 Piston Accumulators and Gas Bottles (4000 PSI & 276 Bar Metric) ..............................................................40-49 d
d
(cid:127) Series 5000 Piston Accumulators and Gas Bottles (5000 PSI & 345 Bar Metric) ..............................................................50-64 a
l
Bladder Accumulators – BA, BG, & BT Series ............................................................................................... 65-80 B
(cid:127) Dimensions ........................................................................................................................................................................... 68
(cid:127) Options .............................................................................................................................................................................74-76 m
(cid:127) Ordering Information......................................................................................................................................................... 78-79 g
a
Diaphragm Accumulators – AD Series ........................................................................................................... 81-86 r
h
(cid:127) Dimensions ........................................................................................................................................................................... 83 p
(cid:127) Options .................................................................................................................................................................................. 84 a
i
(cid:127) Ordering Information.............................................................................................................................................................. 85 D
Inline Pulse-Tone™ Hydraulic Shock Suppressors ..................................................................................... 87-100
™
(cid:127) Dimensions ...................................................................................................................................................................... 92-96 e
(cid:127) Ordering Information.............................................................................................................................................................. 97 en
(cid:127) Accessories ...................................................................................................................................................................... 98-99 nTo
i
l-
Gas Bottles – GB Series ............................................................................................................................. 101-104 ne
Is
Accumulator Accessories........................................................................................................................... 105-114 ul
P
(cid:127) Charging & Gauging Assemblies .................................................................................................................................. 106-111
(cid:127) Unloading Valves ................................................................................................................................................................. 111 s
(cid:127) Bladder Accumulator Repair Tools ....................................................................................................................................... 112 astle
(cid:127) Port Adaptors ...................................................................................................................................................................... 112 Gt
o
(cid:127) Mounting Accessories & Brackets................................................................................................................................. 113-114 B
KleenVent Reservoir Isolators – KV Series ................................................................................................ 115-118
s
Pulse-Tones ........................................................................................................................................................ 119 e
i
r
SurgeKushons – SK Series......................................................................................................................... 121-128 o
s
(cid:127) Dimensions .................................................................................................................................................................. 126-127 s
e
(cid:127) Options & Ordering Information ........................................................................................................................................... 128
c
Sizing Data .................................................................................................................................................. 129-135 c
A
Applications ................................................................................................................................................ 136-138
Application Data Sheet ...................................................................................................................................... 139 nt
en
Installation and Maintenance Instructions ................................................................................................. 141-158 ee
KlV
(cid:127) Hydraulic Piston Accumulators ..................................................................................................................................... 141-146
(cid:127) Hydraulic Piston Accumulators – CE Marking ............................................................................................................... 147-156
s
(cid:127) Bladder Accumulators .................................................................................................................................................. 157-164 n
(cid:127) Bladder Accumulators – CE Marking ............................................................................................................................ 165-178 o
h
(cid:127) Diaphragm Accumulators ............................................................................................................................................. 179-182 s
(cid:127) Inline Pulse-Tone™ ...................................................................................................................................................... 183-185 u
K
(cid:127) Gas Chucks......................................................................................................................................................................... 186 e
Model Number Cross Reference................................................................................................................. 187-200 g
r
u
Offer of Sale........................................................................................................................................................ 208 S
g
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! WARNING
FAILURE OR IMPROPER SELECTION OR IMPROPER USE OF THE PRODUCTS AND/OR SYSTEMS DESCRIBED HEREIN OR RELATED ITEMS CAN CAUSE DEATH, .
PERSONAL INJURY AND PROPERTY DAMAGE. nt
This document and other information from Parker Hannifin Corporation, its subsidiaries and authorized distributors provide product and/or system options for further investigation by users ai
having expertise. It is important that you analyze all aspects of your application, including consequences of any failure and review the information concerning the product or system in the M
current product catalog. Due to the variety of operating conditions and applications for these products or systems, the user, through its own analysis and testing, is solely responsible for
making the final selection of the products and systems and assuring that all performance, safety and warning requirements of the application are met.
e
The products described herein, including without limitation, product features, specifications, designs, availability and pricing, are subject to change by Parker Hannifin Corporation and c
its related companies at any time without notice. sn
se
© Copyright 2003, Parker Hannifin Corporation. All rights reserved. or
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e
1 Parker Hannifin Corporation R
Hydraulic Accumulator Division
Rockford, Illinois USA
Catalog HY10-1630/US Hydraulic Accumulators
nAtepnptlsications Introduction
Parker Accumulators are designed to optimize the performance of your hydraulic system,
while adding safeguards that prolong equipment life. Reduced operating costs and savings
from less downtime and maintenance are the benefits.
Parker Accumulators… Typical Applications
(cid:127) Provide an auxiliary power source by (cid:127) Construction & Mining Equipment –
holding supplemental power to be emergency backup for steering, brake,
used during peak periods. This allows and pilot circuits.
the use of smaller pumps, motors, and (cid:127) Hydrostatic Drives – shock absorption
reservoirs reducing installation and when changing directions.
operating costs.
(cid:127) Injection Molding & Die Casting – high
(cid:127) Protect hydraulic systems and circuit pressure and flows in a short time
components from damage due to period.
thermal expansion and contraction in
(cid:127) Plunger & Diaphragm Pumps –
a closed system.
reduces pump pulsations.
(cid:127) Make up changes in fluid volume to
(cid:127) Fork Lifts & Cherry Pickers – pressure
assure a positive pressure.
spike dampening.
(cid:127) Reduce costly damage to piping
(cid:127) Machine Tools – maintains pressure,
systems, fittings, and gauges by
reduces pump size.
absorbing hydraulic line shocks.
(cid:127) Transportation Vehicles – suspension
(cid:127) Supply emergency fail-safe power to
systems and braking systems.
complete a work safety cycle in the
event of a pump or electric power (cid:127) Turbine Engines – oil supply for
failure. lubrication.
(cid:127) Hold necessary high pressure for long (cid:127) Winches – maintaining line tension.
periods of time while preventing oil
overheating, reducing pump wear, and
saving energy.
(cid:127) Dispense lubricants in a slow, constant
rate to critical equipment wear areas.
2 Parker Hannifin Corporation
Hydraulic Accumulator Division
Rockford, Illinois USA
Hydraulic Accumulators
Catalog HY10-1630/US
PCaegrteifications Introduction
Accumulators and Gas Bottles are pressure vessels which are accumulators and gas bottles. Similar laws, regulations, and/or
subject to safety laws, regulations, and/or ordinances which ordinances apply in other countries as well. Other particular
are valid in the state or country of set-up. For example, in the regulations must be observed in certain industries such as
US most states require ASME Certification on larger bore ship building, aircraft, mining, etc.
ASME Certification
ASME (American Society of Mechanical Engineers) is an Appendix 22 permits that
organization that regulates the design and manufacture of accumulators manufac-
pressure vessels in the United States. Accumulators are tured with “forged” shells,
categorized as unfired pressure vessels and fall under the with openings of a
jurisdiction of ASME Code when required by state law. In 48 specified maximum size,
states, ASME Certification is required on pressure vessels may be Certified with a
used within their boundaries. Accumulators specifically fall design factor of 3:1 in the
under the section of the code referred to as Section VIII, ratio of burst pressure to
Division 1. This section requires certification on vessels with rated pressure.
internal diameters of 6" or greater and that certified vessels
ASME requires that each
carry the “U” symbol on them as evidence that they were
vessel be marked with
designed and manufactured in accordance with the Code. The
the design pressure at
“U” symbol is an internationally recognized symbol of design
the Minimum Design
and manufacturing quality.
Metal Temperature
The essential criteria of ASME Certification is a requirement (MDMT) for the vessel.
of strength and material traceability. Accumulators must be
ASME Certification
manufactured from materials that meet ASME specifications
requires third party
and require a design factor of 4:1 in the ratio of burst pressure
surveillance of an approved quality system and requires
to rated pressure. This 4:1 requirement is mandatory for all
witness by a third party of all hydrostatic testing. And at
accumulators with ASME Certification with the exception
present, unlike many other standards around the world, there
ofthose that comply with a specific rule within the Code called
is no ASME national requirement for periodic inspection of
“Appendix 22”.
accumulators after installation. However, local laws would
dictate such inspections.
Pressure Equipment Directive (PED)
The Pressure Equipment Directive is one of the series of The PED applies in the member states of the European
technical harmonization directives covering subjects such as Union (EU) and the European Economic Area (EEA).
machinery, simple pressure vessels, gas appliances, etc., Similar requirements to the PED have been adopted by
which were identified by the European Community’s program many other countries, which have applied to join the Euro-
for the elimination of technical barriers to trade. The purpose pean Union.
of the PED is to harmonize national laws of Member States
The EU member
regarding the design, manufacture, testing and conformity
states are:
assessment of pressure equipment and assemblies of
Austria
pressure equipment.
Belgium Denmark
The program aims to ensure the free placing on the market
Finland
and putting into service of relevant equipment within the
France
European Union and the European Economic Area.
Germany
The Directive requires that all pressure equipment and Greece
assemblies within its scope must be safe when placed on the Ireland
market and put into service. Italy
Luxembourg
The Pressure Equipment Directive applies to the design,
Netherlands
manufacture and conformity assessment of pressure
Portugal
equipment and assemblies of pressure equipment with
Spain
maximum allowable pressure greater than 0.5 bar above
Sweden
atmospheric pressure (i.e.: 1.5 bar of absolute pressure).
United Kingdom
The PED Conformity Assessment Modules apply to all
The European Economic
accumulators using fluids in Group 2 (i.e.: non-hazardous),
Area (EEA) includes the
with a volume greater than 1 liter and a product of service
15 EU countries listed
pressure (PS) and volume (V) which is greater than 50
above, plus Iceland, Liechtenstein, Norway, and Switzerland.
bar.liter, or for any pressure vessel where PS exceeds 1000
bar.
3 Parker Hannifin Corporation
Hydraulic Accumulator Division
Rockford, Illinois USA
Catalog HY10-1630/US Hydraulic Accumulators
nAtcecnutsmulator Selection Guide Introduction
Making the Right Choice
Hydro-pneumatic accumulators
are the most widely used type of
accumulator in industrial and
mobile hydraulic systems. They
use compressed gas to apply
force to hydraulic fluid. Identical
in their operating principle,
Parker’s piston, bladder and
diaphragm accumulators use
different mechanisms to sepa-
rate the gas from the fluid. It is
this difference – and the result-
ing performance characteristics
– which determines their suit-
ability for different applications.
The correct selection and
application of different style
accumulators is examined in the
following pages.
Piston Advantages Parker’s hydro-pneumatic accumulators regulate the performance of a hydraulic
(cid:127) extremely high flow rates system by providing an additional volume of system fluid, pressurized by an
external gas supply.
(cid:127) high/low temperature tolerance
(cid:127) high compression ratios A correctly specified accumulator can:
(cid:127) withstands external forces (cid:127) reduce shock effects in a system resulting from inertia or
(cid:127) unlimited sizes/mounting external mechanical forces
(cid:127) work well with gas bottles (cid:127) maintain system pressure by compensating for pressure
loss due to leakage
(cid:127) fully serviceable
(cid:127) provide a back-up supply of hydraulic energy to maintain a
Bladder Advantages constant flow when system demand is greater than pump delivery.
(cid:127) dirt tolerant In industrial applications, three types of hydro-pneumatic accumulators are widely
(cid:127) universal application used – the piston type, bladder type and diaphragm type. Each has particular
(cid:127) safety advantages and limitations which should be considered when selecting an
accumulator for a specific application.
(cid:127) quick response
(cid:127) works well on water, Piston accumulators offer greater efficiency and flexibility in most applications, due
low lubricity fluids to their wider range of sizes. Parker’s piston accumulators feature a patented
five-blade V-O-ring which maintains full contact between the piston and the bore,
(cid:127) fully serviceable
without rolling. Sealing remains effective even under rapid cycling at high operating
pressures.
Diaphragm Advantages
Bladder/Diaphragm accumulators are generally preferred for applications where
(cid:127) lightweight, compact
rapid cycling, high fluid contamination and fast response times are required. They
(cid:127) simple, cost effective
provide excellent gas/fluid separation.
(cid:127) dirt tolerant
(cid:127) quick response
4 Parker Hannifin Corporation
Hydraulic Accumulator Division
Rockford, Illinois USA
Hydraulic Accumulators
Catalog HY10-1630/US
PAacgceumulator Selection Guide Introduction
Design Features and Construction
Piston Accumulators Bladder Accumulators Diaphragm Accumulators
Parker piston accumulators consist of Greer bladder accumulators feature a Parker diaphragm accumulators
a cylindrical body, sealed by a gas cap non-pleated, flexible rubber bladder feature a one piece molded
and charging valve at the gas end, and housed within a steel shell. The open diaphragm which is mechanically
by a hydraulic cap at the hydraulic end. end of the bladder is attached to the sealed to the high strength metal shell.
A lightweight piston separates the gas precharging valve at the gas end of the The flexible diaphragm provides
side of the accumulator from the shell. A poppet valve, normally held excellent gas and fluid separation.
hydraulic side. open by spring pressure, regulates A button molded to the bottom of the
fluid flow through the hydraulic port. diaphragm prevents the diaphragm
As with the bladder/diaphragm
Greer’s bladder accumulators are from being extruded out the hydraulic
accumulator, the gas side is charged
available as either top or bottom port. The non-repairable electron-
with nitrogen to a predetermined
repairable units, for optimum flexibility. beam welded construction reduces
pressure. Changes in system pressure
size, weight, and ultimately cost.
cause the piston to rise and fall,
allowing fluid to enter or forcing it to be The bladder/diaphragm is charged with
discharged from the accumulator body. a dry inert gas, such as: nitrogen, to a
set precharge pressure determined by
the system requirements. As system
pressure fluctuates, the bladder/
diaphragm expands and contracts to
discharge fluid from, or allow fluid into,
the accumulator shell.
Fig. 1 Typical bladder, diaphragm and piston accumulators
Charging Charging
Valve Valve
Charging
Valve
Gas Cap
Shell
Shell
Bladder Body
Poppet Piston
Diaphragm Button
Spring
Hydraulic
Fluid Port
Hydraulic Cap
Port
BLADDER DIAPHRAGM PISTON
Gas
5 Parker Hannifin Corporation
Hydraulic Accumulator Division
Rockford, Illinois USA
Catalog HY10-1630/US Hydraulic Accumulators
nAtcecnutsmulator Selection Guide Introduction
Operation
Stage (a) Stage (c) Stage (e)
The accumulator is empty, and The hydraulic system is pressurized. System pressure falls. Precharge
neither gas nor hydraulic sides are System pressure exceeds precharge pressure forces fluid from the accumu-
pressurized. pressure, and fluid flows into the lator into the system.
accumulator.
Stage (b) Stage (f)
The accumulator is precharged. Stage (d) Minimum system pressure is reached.
System pressure peaks. The accumu- The accumulator has discharged its
lator is filled with fluid to its design design maximum volume of fluid back
capacity. Any further increase in into the system.
hydraulic pressure would be prevented
by a relief valve in the system.
Fig 2 Operating conditions of bladder, piston and diaphragm accumulators
(A) (B) (C) (D) (E) (F)
Gas
6 Parker Hannifin Corporation
Hydraulic Accumulator Division
Rockford, Illinois USA
Hydraulic Accumulators
Catalog HY10-1630/US
PAacgceumulator Selection Guide Introduction
Accumulator Selection
Table 1: Relative Outputs of a 40 litre Accumulator
When selecting an accumulator for a particular application,
both system and performance criteria should be considered. Compression System Recommended Fluid Output
Ratio Pressure, Precharge, GPM
To ensure long and satisfactory service life, the following
PSI PSI
factors should be taken into account.
(cid:127) (cid:127) max min Bladder Piston Bladder Piston
Failure mode Output volume
(cid:127) (cid:127) 1.5 3000 2000 1800 1900 2.79 3.00
Flow rate Fluid type
(cid:127) Response time (cid:127) Shock suppression 2 3000 1500 1350 1400 4.23 4.41
(cid:127) (cid:127)
High frequency cycling Mounting position 3 3000 1000 900 900 5.70 5.70
(cid:127) (cid:127)
External forces Sizing information 6 3000 500 ❋ 400 ❋ 6.33
(cid:127) (cid:127)
Certification Safety ❋ Below required minimum operating ratio of 4:1.
(cid:127)
Temperature effect
Flow Rate
Failure Modes Table 2 shows typical maximum flow rates for Parker’s
accumulator styles in a range of sizes.
In certain applications, a sudden failure may be preferable to
a gradual failure. A high-speed machine, for example, where The larger standard bladder designs are limited to 220 GPM,
product quality is a function of hydraulic system pressure. although this may be increased to 600 GPM using a highflow
Because sudden failure is detected immediately, scrap is port. The poppet valve controls flow rate, with excessive flow
minimized, whereas a gradual failure might mean that causing the poppet to close prematurely. Flow rates greater
production of a large quantity of sub-standard product could than 600 GPM may be achieved by mounting several
occur before the failure became apparent. accumulators on a common manifold – see Large/Multiple
Accumulators, page 11.
A bladder/diaphragm accumulator would be most suitable for
this application. For a given system pressure, flow rates for piston accumula-
tors generally exceed those for bladder designs. Flow is
Conversely, where continuous operation is paramount and
limited by piston velocity, which should not exceed 10 ft/sec.
sudden failure could be detrimental as, for example, in a
to avoid piston seal damage. In high-speed applications,
braking or steering circuit on mobile equipment, a progres-
high seal contact temperatures and rapid decompression of
sive failure mode is desirable. In this application, a piston
nitrogen that has permeated the seal itself, can cause
accumulator would be appropriate.
blisters, cracks and pits in the seal surface. In this type of
Output Volume
application a bladder style accumulator would be better
The maximum sizes available of each type of accumulator suited.
determine the limits of their suitability where large output
volumes are required. There are, however, several methods
Table 2: Maximum Recommended
of achieving higher output volumes than standard accumula-
Accumulator Flow Rates
tor capacities suggest - see Large/ Multiple Accumulators,
page 11. GPM at 3000 PSI
Table 1 compares typical fluid outputs for Parker’s 10 gallon Bladder
Piston Bladder Diaphragm Piston Bladder High Diaphragm
piston and bladder accumulators operating isothermally as Bore Capacity Capacity Std. Flow
auxiliary power sources over a range of minimum system
2 1 qt. .5-10 cu. in. 100 40 11
pressures. The higher precharge pressures recommended
for piston accumulators result in higher outputs than from 3 1 gal. 20-85 cu. in. 220 150 26
comparable bladder accumulators. Also, bladder accumula-
4 2.5 gal. 120-170 cu. in. 397 220 600 42
tors are not generally suitable for compression ratios greater
than 4:1, as these could result in excessive bladder deforma- 6 and 818 220 600
tion. 7 Larger 1199 220 600
Piston accumulators have an inherently higher output
9 1982 220 600
relative to their overall dimensions, which may be critical in
locations where space is limited. Piston accumulators are 12 3450
available in a choice of diameters and lengths for a given
capacity, whereas bladder and diaphragm accumulators are
frequently offered in only one size per capacity, and fewer
sizes are available. Piston accumulators can also be built to
custom lengths for applications in which available space is
critical.
7 Parker Hannifin Corporation
Hydraulic Accumulator Division
Rockford, Illinois USA
Catalog HY10-1630/US Hydraulic Accumulators
nAtcecnutsmulator Selection Guide Introduction
Fluid Type
Bladder/Diaphragm accumulators are more resistant to
4000
damage caused by contamination of the hydraulic fluid than
piston types. While some risk exists from contaminants
trapped between the bladder and the shell, a higher risk of
failure exists from the same contaminants acting on the
piston seal. PSI
–
Bladder accumulators are usually preferred to piston type ure 2000
accumulators for water service applications. Water systems s
s No accumulator in circuit
e
tend to carry more solid contaminants and lubrication is poor. Pr
Piston accumulator
Both the piston and bladder type units require some type of
preparation to resist corrosion on the wetted surfaces. Bladder accumulator
Piston accumulators are preferred for systems using exotic
fluids or where extremes of temperature are experienced as, 0
0 1000 2000
compared to bladders. Piston seals are more easily molded
Time – ms
in the required special compounds, and may be less
expensive.
Fig.4 Shock wave test results – Example 1
Response Time
In theory, bladder and diaphragm accumulators should Installing a Greer 1 gallon piston accumulator at the valve
respond more quickly to system pressure variations than reduces the transient to 100 PSI over relief valve setting
piston types. There is no static friction to be overcome as (medium trace).
with a piston seal, and there is no piston mass to be acceler- Substituting a 1 gal. bladder accumulator further reduces the
ated and decelerated. In practice, however, the difference in transient to 80 PSI over relief valve setting (dark trace), an
response is not great, and is probably insignificant in most improvement of only 20 PSI and of little practical signifi-
applications. cance.
This applies equally in servo applications, as only a small
percentage of servos require response times of 25ms or
Example 2
less. This is the point where the difference in response
A second, similar test using 0.625 in. tubing and a relief
between piston and bladder accumulators becomes signifi-
valve setting of 2650 PSI (Fig. 5) results in a pressure spike
cant. Generally, a bladder accumulator should be used for
of 2011 PSI over relief valve setting without an accumulator
applications requiring less than 25ms response time, and
(light trace).
either accumulator type for a response of 25ms or greater.
A Parker piston accumulator reduces the transient to 107
PSI over relief valve setting (medium trace), while a bladder
Shock
accumulator achieves a transient of 87 PSI over relief valve
Suppression setting (dark trace). The difference between accumulator
types in shock suppression is again negligible.
Shock control does not
necessarily demand a
bladder/diaphragm
accumulator.
Example 1 4000
A test circuit (Fig.3)
includes a control valve
situated 118 ft. from a
pump supplying fluid at SI
P
29.6 GPM. The circuit –
uses 1.25 in. tubing and Tmuabkinegs length ure 2000
tohpee nre aliet f2 7va5l0v eP iSsI .set to psdeuisrmtvaopnv-ctaoel-v 3e6m. Press NPios taocnc aucmcuulmatuolra itno rcircuit
Shutting the control valve
Bladder accumulator
(Fig.4) produces a
pressure spike of 385 PSI
over relief valve setting 0
0 1000 2000
(light trace).
Time – ms
Fig.3 Test circuit to generate
and measure shock waves in Fig.5 Shock wave test results – Example 2
a hydraulic system
8 Parker Hannifin Corporation
Hydraulic Accumulator Division
Rockford, Illinois USA