PistonAccumulatorsPistonAccumulators

2

HYDACPISTONACCUMULATORS

TABLE OF CONTENTS Page:1. DESCRIPTION 3

INTRODUCTION 3CONSTRUCTION 3PISTON TYPES 4EFFECTS OF SEAL FRICTION 4

2. APPLICATIONS 63. TECHNICAL DATA 8

OPERATION 8TEMPERATURE EFFECT 8FORMULAS FOR SIZING ACCUMULATORS 8SIZING EXAMPLE 9

4. INSTALLATION REQUIREMENTS 105. MODEL CODE 11 - 136. DIMENSIONS 14 - 15

3

1.DESCRIPTIONINTRODUCTIONFluids are practicallyincompressible and cannottherefore store pressureenergy.

The compressibility of a gas(nitrogen) is utilized in hydro-pneumatic accumulators forstoring fluids. HYDAC pistonaccumulators are designed onthis principle, using nitrogenas the compressible medium.

A piston accumulator consistsof a fluid section and a gassection with the piston actingas a gas proof screen. Thegas section is precharged withdry nitrogen gas.

The fluid section is connectedto the hydraulic circuit so thatthe piston accumulator drawsin fluid when the pressure increases thus compressingthe gas. When the pressuredrops, the compressed gasexpands and forces the storedfluid into the circuit.

CONSTRUCTION

gas valve

end cap

sealingsystem

piston

cylinder

O-ring

fluid inlet

HYDAC piston accumulatorsconsist of:

• a cylinder with a finelyfinished internal surface.

• an end cap on the gas sideand the oil side, sealed witho-rings.

• lightweight metal piston

• a variety of sealing systemsare available depending on theapplication.

• type 2 shown above

SEALING SYSTEMSPrecise information about theproposed operating conditions isrequired in order to select themost appropriate sealing system.Important criteria for thisselection are:

• design pressure.

• effective pressure differential.

• number of actuations or cycles.

• temperature fluctuation.

• operating fluid.

• cleanliness of fluid.

• maintenance requirements.

SEAL MATERIALSThe following sealing elastomersare available, depending on theoperating conditions:

NBR / acrylic nitrile butadienerubber (Perbunan*)FKM / fluoro-rubber (Viton*)AU / polyurethane (Vulkollan*)

Suitable materials are also availablefor low temperature applications.

*trade names

4

PISTON TYPETYPE 1

Application:Standard design for generalaccumulator operation withoutspecial requirements.Note: Piston friction must be taken intoaccount for sizing purposes.

TYPE 2

Application:Low-friction design for higherpiston speeds, slow movementswithout stick-slip effect and highnumber of actuations (millions)1).

Note: Filtration ≤ 10 µ absolute.(ISO 16/13)

TYPE 3

Application:General duty, cycle requirements100,000’s1).

1)Actual cycles achieved will vary withoperating parameters.

SYSTEM MOUNTINGHYDAC piston accumulatorsoperate in any position. Verticalinstallation is preferable with thegas side up.

ADVANTAGES OF HYDACPISTON ACCUMULATORS:

• complete range from 1 quartto 100 gallons nominalvolume.

• high ratios possible betweenprecharge pressure and max.working pressure.

• high flow rates – up to 4700gpm from one accumulator.

• power savings.

• gas-proof and leak-free.

• no sudden discharge of gaswhen seal is worn.

• space efficient.

• piston location monitoringavailable.

Further advantages of using thelow-friction sealing system(type 2):

• minimum friction.

• suitable for low pressuredifferentials.

• no start-up friction, no stick-slip.

• low noise, no vibration.

• high piston speeds up to12 fps continuous

• improved accumulatorefficiency.

• high life expectancy

• low maintenancerequirements.

EFFECT OF SEAL FRICTIONThe permissible piston velocitydepends on the sealing friction.Higher piston velocities arepossible where there is lesssealing friction.

HYDAC piston accumulators withlow friction piston seals allowcontinuous operating velocities of12 fps with short excursions to15 fps.Small pressure differentialsbetween gas and oil side improvethe effectiveness of HYDACpiston accumulators.To emphasize the friction effecton the pressure curve during anaccumulation cycle,measurements with varioussealing systems are illustrated.The measurement graphs are atrue representation of the gasand oil pressure of the pistonaccumulator with various sealingsystems. The comparison ofthese two measurements showclearly the difference in thepressure differential between gasand oil side:Graph 1: ∆p max. dyn. ≈ 145 psiGraph 2: ∆p max. dyn. ≈ 14.5 psiThe effect of the workingpressure on the sealing friction isparticularly striking in pistontype 1.Abrupt movements during pistonstart-up (stick-slip effect) are notpresent in graph 2.

5

Test rig to determine sealing friction

Graph 1: piston type 1

Graph 2: piston type 2(low-friction model)

oil pressure

gas pressure

0 5 10 15 20 t in sec

p inpsi2175

1450

725

145 0

oil pressuregaspressure

p inpsi2175

1450

725

145

0

0 5 10 15 20 t in sec

2. APPLICATIONSTYPICAL APPLICATIONSENERGY STORAGEIn systems with widely differingoil requirements or long cyclesthe only economical solution is touse a hydro-pneumaticaccumulator. During low fluidconsumption the accumulator ischarged. When requirementsexceed the pump feed flow, theappropriate amount of fluid willbe drawn from the accumulator.

Smaller pumps can be installedas a result and less power isrequired, less heat is generated,installation and maintenance aresimplified, purchasing andoperating costs are reduced.

Force EquilibriumThe backing rollers used inrolling machines are hydraulicallypre-stressed in order to stabilizethe pre-set roller clearance. Thepressure necessary for this ismaintained at a constant level byaccumulators. HYDAC pistonaccumulators therefore take theplace of cumbersome counterbalances.Advantage:Inertia-free counterbalancing,rapid response, little base loadrequired, space saving, simpleoperation and servicing.

6

Blast Furnace Hydraulics:10 Piston Accumulators, SK 210-100 with 211gallons of auxiliary nitrogen volume.

Clay Gun Machine:2 Piston Accumulators, SK 350-80 with 264gallons of auxiliary nitrogen volume.

Roller Balancing: 9 Piston Accumulators, SK 210-50 with 317 gallons of auxiliary nitrogen volume.

Pump Flow Ratewithout Accumulator

V1 + V2 = V3 + V4

V1 V2 With Accumulator

V3 V4

Working Cycle Time

Flo

w R

ate

7

High Speed InjectionMolding MachineShort cycles and low pressuredifferentials are typical for thesehigh speed injection moldingmachines.

Accumulator Cycle

HYDAC piston accumulators ofthe back-up type, with low-friction seals, are ideal forhandling the high flow ratesrequired during the injectionprocess. This reduces the powerrequirements to a fraction of thatrequired by machines withoutaccumulators.The pump start-up time isminimized by the electrical endposition control.The smooth operation of theHYDAC piston accumulatorimproves quality anddimensional accuracy of theinjection molded product.

Crash SimulatorA flow rate of 23,000 gpm withpressures operating between4200 and 3900 psi are requiredto accelerate the crash simulatorcatapult. This hydraulic powermust be converted into motionenergy in the shortest possibletime, loosing as little pressureas possible. HYDAC pistonaccumulators, special models,with auxiliary nitrogen volumeand electronic pressuremonitoring were designed forthis application.

High Speed Injection Molding Machine:Piston Accumulators SK 210-6 with 20 gallons of auxiliary nitrogen volume.

Crash Simulator:6 Piston Accumulators SK 350-16 each with 63 gallons of auxiliary nitrogen volume.

pressurein psi

2030

2015

2000

1990

0.85 timein seconds

8

3.TECHNICAL DATADESCRIBING THEOPERATION OFPISTON ACCUMULATORS:The piston accumulator isprecharged with nitrogen. Thepiston sits against the end capand covers the fluidconnection.

The minimum working pressureshould be approximately 75 psiabove the gas prechargepressure. This should preventthe piston from striking the endcap every time the accumulatoris cycled, striking the end capon each cycle is notrecommended or allowed.

Once the max. workingpressure is reached theeffective volume∆V = V1 - V2 is defined.

p0 = gas precharge pressurep1 = min. working pressurep2 = max. working pressureV0 = effective gas pressureV1 = gas volume at p1V2 = gas volume at p2

Recommendations of GasCharge PressureThe selection of gas prechargevaries from system to system. Ingeneral we suggest the following:p0 ≤ p1 -75 psi

Seal friction pressure, lowsystem pressure, and low systemdifferential pressure are allcritical factors when selecting thegas precharging pressure, forassistance, please consultHYDAC.FORMULAS FOR

SIZING ACCUMULATORSThe compression and expansionprocesses taking place in ahydro-pneumatic accumulator aregoverned by the general gaslaws. The following applies forideal gases:p0 x V0

n = p1 x V1n = p2 x V2

n,where the time related change ofstate is represented by thepolytropic exponent ‘‘n”. For slowexpansion and compressionprocesses which occur almostisothermally, the polytropicexponent can be set at n = 1.For rapid processes, theadiabatic change of state can becalculated using n = K = 1.4(for nitrogen as a diatomic gas)1).For pressures above 3000 psithe real gas behavior deviatesconsiderably from the ideal one,which reduces the effective fluidvolume ∆V. In such cases acorrection is made which takesinto account a change in theadiabatic exponent (k).By using the following formulas,the required gas volume V0 canbe calculated for variousapplications.Low pressure (up to 150 psi) mustalways be represented asabsolute pressures in theformulas.Calculation formulas:

polytropic: V0 = ∆V

( p0 ) 1/n – ( p0 ) 1/np1 p2

isothermal:V0 = ∆V

(n=1) ( p0 ) – ( p0 ) p1 p2

adiabatic: V0 = ∆V(n=k=1.4) ( p0) 0.714– ( p0 ) 0.714

p1 p2

Correction factors to take intoaccount the real gas behavior2)

for isothermal change ofcondition:

V0, real = ci x V0, ideal or

∆V0, real = ∆V idealci

for adiabatic change of condition:V0, real = ca x V0, ideal or

∆V0, real = ∆V idealca

1) An estimate of the accumulator size andselection of precharge pressure can be calculatingas shown in the example. For more accurate sizingand design assistance, please contact HYDAC.2) The correction factors can be taken from thegraphs in the next column, depending on thepressure ratio p2/p1 and the maximum workingpressure p2, which is given as a parameter, for anisothermal or adiabatic change of condition.

1 2 3

P0 P1 P2

V0 V1

V2

TEMPERATURE EFFECTTo ensure that the recommendedprecharge pressure ismaintained, even at relatively lowor high operating tempertures,the gas precharge pressureshould be adjusted fortemperature. The formula belowrelates the prechargetemperature (T0) to maximumoperating temperature (T2).Please refer to the sizingexample on page 9.

Fahrenheit:p0,T0 = p0,T2 x ( T0 + 460) T2 + 460

T0 = precharge temperature

in ºFT2 = Maximum operating

temperature in ºF

p0,T0 = gas precharge pressureat precharge temperature

p0,T2 = gas precharge pressureat maximum operatingtemperature

Celsius:p0,T0 = p0,T2 x ( T0 + 273) T2 + 273

T0 = precharge temperaturein ºC

T2 = maximum operatingtemperature in ºC

p0,T0 = gas precharge pressureat precharge temperature

p0,T2 = gas precharge pressureat maximum operatingtemperature

PERMISSIVE VELOCITIESContinuous recommendedoperating velocities:Type 1: 5 fpsType 2: 12 fpsType 3: 3 fps

Gas VelocityThe flow velocities in the gasconnecton and pipe systemshould be limited to 60 fps whenusing piston accumulators of theback-up type. Gas velocities ofover 120 fps should never beused.

Fluid VelocityIn order to limit the pressure dropwhen the fluid is displaced, thevelocity should not exceed 30 fpsin the fluid port area.

1 2 3

1 2 3

∆V

1 2 3

9

BACK-UPNITROGEN BOTTLESThe volume of nitrogen in theaccumulator can only becompressed slightly at lowdifferential pressure betweenmin. and max. working pressures.Therefore the effective storagevolume of the accumulator iscorrespondingly small. Whensizing the so-called back-upversion, the procedure is exactlythe same as for the singleaccumulator, where V0 representsthe total volume of accumulatorand nitrogen bottles.

The calculation is iterative; aftereach step it has to be checkedwhether the effective accumulatorvolume is sufficient to accomodatethe oil volume for isothermalcharging from precharge pressureto working pressure. Checkingeffective volume for back-up model

∆V’ = V0 x (1 - p0)p2

∆V’ ≤ 0.75 x V0

Sizing ExamplePiston accumulators,back-up type.Requirement:9.25 gallons of fluid must bedelivered between maximumworking pressure of 2900 psi,and minimum working pressureof 1740 psi in 2 seconds(adiabatic condition).Recharge time is 4 minutes.The working temperture is aconstant 104ºF.Given parameters:max. working pressure:p2 = 2900 psimin. working pressure:p1 = 1740 psieffective volume:∆V = 9.25 gal. in 2 sec.working temperature (constant):T = 104ºFRequired:a) accumulator size taking into

account the real gas behaviorb) gas precharge pressure p0

at 68ºFSolution:Since this is a rapid process, anadiabatic change in state isassumed.1.) Selection of precharge

pressure at max. workingtemperature

p0 ≈ p1 - 75 psip0 ≈ 1740 - 75 = 1665 psi

2.) Calculation of required gasvolume (ideal gas):

V0 ideal = ∆V

(p0,T) 0.714 ( p0,T) 0.714

p1 - p2

= 9.25

(1665)0.714 (1665)0.714

1740 - 2900

= 31.2 gal.

3.) Determination of correctionfactor for an adiabatic changein state:

p2/p1 ≈ 1.66Ca = 1.195V0 real = Ca x V0 ideal

= 1.195 x 31.2= 37.3 gal.

Start with multiplying the requiredfluid volume by 1.5;9.5 gal. (1.5) = 14.25 gallons.Checking the “effective gas vol”column on pg 14 or pg 15:– there is no 14.25 gallon

accumulator– therefore, use next larger size

= 15 gallonCalculate gas volume:

37.3 gal. - 15 gal. = 22.3 gal. min.– choose next larger standard size

= 25 gallon– therefore: V0 = 40 gal. = 15 + 254.) Required effective accumulator

gas volume or size:∆V’ = V0 (1 – p0)p2

= 40 (1 – 1665)2900= 17 gal.

The result shows that theaccumulator volume was toosmall. The next size up is 20 gal.

5.) Repeating step 4:∆V’ = 45 ( 1– 1665 )2900

= 19 gal.The accumulator is sufficient.Selected:1 Accumulator SK350 - 75 A21 Nitrogen bottles 25 gal. eachCalculation of prechargepressure (p0) at 20ºC:

p0,T0 = p0,T2 x ( T0 + 460)T2 + 460

= 1665 x ( 68 + 460)104 + 460

= 1558.7 psi

Result (T0 = 68˚F):p 0,T0, = 1560 psi

Correction Factors forIsothermal Change in State

Correction Factor for AdiabaticChange of Condition

300 bar (4350 psi)

ma x. working pressure p2 = 400 bar (5800 psi)

200 bar (2900 psi)

max. working

pressure p2 = 400 bar (5800 psi)

300 bar (4350 psi)200 bar (2900 psi)

1.7

1.6

1.5

1.4

1.3

1.2

1.1

1 2 3 4

Pressure Rat io p2/p1

Co

rre

cti

on

Fa

cto

r C

i

1.7

1.6

1.5

1.4

1.3

1.2

1.1

1 2 3 4

Pressure Rat io p2/p1

Co

rre

cti

on

Fa

cto

r C

i

10

4. INSTALLATIONREQUIREMENTS

GENERAL SUGGESTIONSWARNING!Hydraulic accumulators arepressurized vessels and onlyqualified technicians shouldperform repairs. Never weld,braze or perform any type ofmechanical work on theaccumulator shell. Always drainthe fluid completely from theaccumulator before performingany work, such as recommendedrepairs (see MaintenanceInstructions) or connectingpressure gauges. Precharge newor repaired accumulators with drynitrogen to the proper gasprecharge pressure (p0).For more complete details,please refer to HYDAC Operatingand Installation Instructions.HYDAC suggests a thoroughinspection including a pressuretest every 5 to 10 yearsdepending upon the application.Country of installation Pressurevessel codes vary dependingupon the country of installation.In the United States and Canadapressure vessels are governedby the ASME pressure vesselcode.HYDAC manufactures accordingto these standards.For installation in countriesoutside of the United States,please consult HYDAC forappropriate certifications. Someselective country of installationcodes are shown below*;please refer to page 11:

Australia FAustria DBrazil KCanada S1China A9Germany AFrance BGreat Britain (U.K.) KItaly MJapan PMexico EUSA SOthers Upon Request

Elastomer Compatibility TableIn order to maximize system performance it is important to match yoursystem fluid and its temperature range with the appropriate elastomercompound. The table below illustrates the most common ones. Forspecial requirements, please consult HYDAC.

Compound Temperature Range1) Some Typical Fluids2)

NBR (BUNA N) + 5ºF to + 180ºF mineral oil,+ 32ºF to + 180ºF water, water glycol

AU (POLYURETHANE) + 14ºF to + 176ºF mineral oil

FPM (VITON) + 5ºF to + 300ºF chlorinated hydrocarbon

Notes:1. The operating temperature range does vary with fluid types, please

consult HYDAC for more specific fluid data.

2. The above typical fluids are some examples of the most common fluids,please consult HYDAC for more specific data. For non hydraulicprocess fluids, HYDAC MUST be consulted.

3. For temperatures below -40ºF and above +200ºF, please consultHYDAC for maximum allowable working pressures of the pressurevessels.

4. For other applications not listed, please consult HYDAC.

* The European Community (EC) has the Pressure Equipment Directive (PED) thatis being phased in. Contact HYDAC for details.

!!CAUTION

Gas Charging

Pressurized Vessel –Use Dry Nitrogen Gas Only!

11

5. MODEL CODESK350 - 20 / 2 1 1 2 S - 210 F C F - V E - 18 E - 1

SeriesSK 350 - 3000 psi

SK 600 - 5000 psi

Nominal Volume (in liters)

Material and piston typePiston Type (see page 4)Piston Material

1 = aluminum2 = C-steel (machined)3 = stainless steel (machined)4 = C-steel with surface protection5 = aluminum (cold impact formed)

Cylinder and End Cap Material1 = C-steel (machined)2 = C-steel with surface protection3 = stainless steel6 = TT-steel (low temperature)

Seal Material (including piston seals)2 = NBR205 = NBR21 (low temperature)8 = PUR (polyurethane)

Country of InstallationS = USA

Maximum Working Pressure210 = 3000 PSI345 = 5000 PSI

Fluid ConnectionType of Connection (refer to table 1 on following page)Standard / Specification of the type of connection (refer to tables 2 & 3 on following page)Size of Connection (refer to tables 4 & 5 on following page)

Gas Side ConnectionType of Connection (refer to table 1 on following page)Standard / Specification of the type of connection (omit if type V was chosen) (refer to tables 2 & 3 on following page)Size of Connection (refer to tables 4 & 5 on following page)

Piston Diameter15 = 150mm18 = 180mm25 = 250mm35 = 355mm

Supplementary EquipmentA = electrical limit switch - 35mm stroke M = magnetic flapper indicationB = electrical limit switch - 200mm stroke S = cable tension measurement systemC = electrical limit switch - 500mm stroke U = ultrasonic measurement systemK = protruding piston rod E.. = special switch (fixed and adjustable)

Safety Devices1 = burst disc (indicate nominal pressure)2 = gas safety valve3 = temperature fuse plug

12

Table 1 - Connection TypeCode DescriptionA threaded connection (female)B threaded connection (male)F flange connectionH protruding flangeK combination connectionV gas valve type

Table 2 - Standard / Specification, Threaded ConnectionCode DescriptionA thread to ISO 228 (BSP)B thread to DIN 13 or ISO 965/1 (metric)C thread to ANSI B1.1 (UN..-2B, seal SAE J 514D thread to ANSI B1.20.3 (NPT)S special type

Table 3 - Standard / Specification, Flange ConnectionCode DescriptionA thread to DIN standardsB flange to ANSI B 16.5C SAE flange (3000 psi)D SAE flange (6000 psi)E high pressure block flange (MM-Rexroth, AVIT, HAVIT) PN320S special flange

Table 4 - Threaded Model Connection SizesSee Code, Size

Table 3 A B C D E F G H J K L MA G1/8 G1/4 G3/8 G1/2 G3/4 G1 G1 1/4 G1 1/2 G2 G2 1/2 G3

B M10x1 M12x1.5 M14x1.5 M16x1.5 M18x1.5 M22x1.5 M27x2 M33x2 M42x2 M48x2 M60x2

C 5/16- 3/8- 7/16- 1/2- 9/16- 3/4- 7/8- 1 1/16- 1 3/16- 1 5/16- 1 5/8 1 7/824UNF 24UNF 20UNF 20UNF 18UNF 16UNF 14UNF 12UNF 12UN 12UN 12UN 12UN

D 1/16-27 1/8-27 1/4-18 3/8-18 1/2-14 3/4-1 1/2 1-1 1/2 1 1/4-1 1 1/2-1 1/2 2-1 1/2 2 1/2-8NPT NPT NPT NPT NPT NPT NPT NPT NPT NPT NPT

Table 5 - Flange Model Connection SizesSee Code, Size

Table 3 A B C D E F G H J K L MA DN15 DN25 DN40 DN50 DN65 DN80 DN100 DN125 DN150 DN200

B 1/2”- 1”- 1 1/2” 2” 2 1/2” 3” 1/2” 1” 1 1/2” 2” 2 1/2”1500# 1500# 1500# 1500# 1500# 1500# 2500# 2500# 2500# 2500# 2500#

C 1/2” 3/4” 1” 1 1/4” 1 1/2” 2” 2 1/2” 3” 3 1/2” 4” 5”

D 1/2” 3/4” 1” 1 1/4” 1 1/2” 2”

E DN32 DN40 DN50 DN65 DN80 DN100 DN125 DN150

Table 6 - Gas Valve ModelCode DescriptionA gas valve G3/4 male with M28x1.5/M8B gas valve end connection M28x1.5/M8C gas valve 1/2”-20 UNF male with M16x2 (ISO 10945)D gas valve M14x1.5 male with external M16x1.5E gas valve G3/4 male with 7/8-14 UNF-VG8

5. MODEL CODE - (continued - support tables)

6. DIMENSIONS: FLANGES

Flange Connection

SAE - Flange Connection (3000 PSI)(Code 60/61 SAE Type 11, J518 Bolt Pattern)

SAE - Flange Connection (6000 PSI)(Code 62 SAE Type 11, J518 Bolt Pattern)

13

Connection Type F

Size D1 D2 D3 L M..(in) (in) (in) (in) DIN 13

DN 32 1.18 2.21 2.84 0.79 12

DN 40 1.77 3.23 3.86 1.02 16

DN 50 2.13 3.86 4.65 1.26 20

DN 65 2.87 4.69 5.71 1.50 24

DN 80 3.50 5.63 6.89 1.69 30

Connection Type F

Size A B D1 D2 M..(in) (in) (in) (in) DIN 13

1” 2.06 1.03 1.00 1.65 10

1 1/4” 2.31 1.19 1.25 1.89 12

1 1/2” 2.75 1.41 1.50 2.36 14

2” 3.06 1.69 1.94 2.75 14

2 1/2” 3.50 2.00 2.38 3.35 14

3” 4.19 2.44 2.94 3.94 161) P = max. 2500 PSI2) Q = max. 2000 PSI

Connection Type F

Size A B D1 D2 M..(in) (in) (in) (in) DIN 13

1” 2.25 1.09 1.00 1.81 121 1/4” 2.63 1.25 1.25 2.20 121 1/2” 3.13 1.44 1.50 2.56 16

2” 3.81 1.75 1.94 3.15 202 1/2” 4.88 2.31 2.38 4.33 22

3” 6.00 2.81 2.94 5.12 27

D3

D2

D1

M..

0.08

L

D2

D1 A

M..

0.08 B

D2

D1 A

M..

0.08 B

6.1 DIMENSIONS:PISTON ACCUMULATORType 1 & 2

SK 350/SK 600 (3000/5000 PSI)

VERSION 1Connection to FPK

M28 x 1.5

Flange connection see table 2

VERSION 4Connection to FPS

8V1 - ISO 4570

Thread connection see table 1

SK 350 (maximum working pressure 3000 psi)

Eff. ØD1 ØD2Size Gas Weight A in. in.

Vol. lbs. kg in. mm (mm) (mm)Gals.

10 2.5 233 107 28 711

16 4 283 128 37.2 945

20 5 316 143 43.4 1102 7.09 8.62

30 7.5 400 181 58.9 1496 (180) (219)

40 10 482 219 74.4 1890

50 12.5 566 257 89.9 2283

40 10 788 357 49 1245

50 12.5 882 400 57.1 1450

60 15 974 442 65 1651

75 20 1114 505 77.1 1958

100 25 1347 611 97.1 2466 9.841 12.21

115 30 1488 675 109.2 2774 (250) (310)

135 35 1676 760 125.3 3183

150 40 1816 824 137.4 3490

170 45 2004 909 152.4 3871

190 50 2194 994 168.4 4277

100 25 1859 843 61.9 1572

115 30 1986 901 67.9 1725

150 40 2287 1037 81.8 2078 13.98 17.09

190 50 2630 1193 97.7 2482 (355) (434)

250 65 3144 1426 121.6 3089300 80 3572 1620 141.5 3594

SK 600 (maximum working pressure 5000 psi)

Eff. ØD1 ØD2Size

Gas Weight A in. in.Vol. lbs. kg in. mm (mm) (mm)

Gals.10 2.5 302 137 28 71116 4 402 182 37.2 94520 5 447 203 43.4 1102 7.09 9.6130 7.5 606 275 58.9 1496 (180) (244)40 10 736 334 74.4 189050 12.5 884 401 89.9 228340 10 1110 503 49 124550 12.5 1254 569 57.1 145060 15 1396 633 65 165175 20 1611 731 77.1 1958100 25 1969 893 97.1 2466 9.84 13.31115 30 2184 990 109.2 2774 (250) (338)135 35 2472 1121 125.3 3183150 40 2689 1220 137.4 3490170 45 2977 1350 153.5 3899190 50 3265 1481 169.5 4305

14

1.79

0.08

A1.

34

D1

D2

15

16+

220

ø721 7/8"-12UN

46

7/8" - 14

D1

D2

2 x

45º

1

A ..

..±3

Ra1.6

Version 4Connection FPS

SAE 2" - 3000PSI4 x M12

SAE 2" - 6000PSI4xM20

SK 350 (maximum working pressure 5000 psi)

Eff. ØD1 ØD2Size

Gas Weight A in. in.Vol. lbs. kg in. mm (mm) (mm)

Gals.4 1 137 62 16.9 4306 1.5 157 71 21.5 54510 2.5 199 90 30.3 770 5.9 7.120 5 304 138 52.6 1335 (150) (180)40 10 514 233 97.2 247060 15 723 328 141.7 3600

1.34

6.2 DIMENSIONS:PISTON ACCUMULATORType 3

VERSION 4Connection to FPS

7/8” - 14

VERSION 1Connection to FPK

M28 x 1.5

©C

opyr

ight

200

0 H

YD

AC

TE

CH

NO

LO

GY

CO

RP

OR

AT

ION

- B

roch

ure

- P

isto

n A

ccum

ulat

ors

#020

6859

7 /

08.0

0

HYDAC CORPORATION2280 City Line Road • Bethlehem, PA 18017Phone (610) 264-9503 • Fax (610) 264-7529www.hydacusa.com • powerup@hydacusa.com

Bladder AccumulatorsThe bladder style accumulator is a great general purpose accumulator. It hasa wide range of sizes for energy storage requirements and is well suited forshock applications.

Nominal volume: 1 qt. to 15 gal.

Max. working pressure: 3000, 5000 and up to 15000 psi

Flow rate: up to 480 gpm

Other Products from HYDAC’s Accumulator Line

Diaphragm AccumulatorsDiaphragm accumulators are frequently used where small volumes arerequired, light weight is important, a higher pressure ratio is required (up to10:1), and low cost is a prime factor. Two styles are available weld (non-repairable) and threaded (repairable). Both are suited for energy storage andshock applications.

Nominal volume: 5 in3 to 1 gal.

Max. working pressure: 3000, 4700, and up to 10,000 psi

Flow rate: up to 40 gpm

Safety & Shut-off BlocksHYDAC offers a complete range of safety and shut-off blocks designed toprotect, shut-off, and discharge hydraulic accumulators or user units.

Charging & GaugingTo maintain system performance, HYDAC recommends a regular check of thegas precharge pressure. A loss in the gas precharge pressure will cause adrop in the system efficiency and could cause damage to the bladder,diaphragm or piston accumulator. By means of a charging and gauging unit,hydro-pneumatics accumulators are precharged with dry nitrogen or theirexisting gas precharge pressure is checked. For these purposes, a chargingand gauging unit is connected to a commercially available nitrogen bottle viaa flexible hose. The charging and gauging units incorporate a gauge, checkvalve in the charging connection, manual bleed valve and T-handle.

Request catalog # 02071832

Request catalog # 02071831

Request catalog # 02071830

Request catalog # 02071833