HYDRO PNEUMATIC ACCUMULATORS - … speaking, it is used to make pump/motor size small and also used...

Courtesy of JAXACourtesy of JAXA

2014

HYDRO�PNEUMATICACCUMULATORS

Title:表紙.ec6 Page:1 Date: 2014/12/15 Mon 09:38:19

Functions & Effects

■ Energy Storage (power compensation) This is the most common usage of the accumulator to store energy from an external pressure source during idle time and to discharge the energy as necessary. Concretely speaking, it is used to make pump/motor size small and also used as an auxiliary power source in emergency, as a hydraulic starter for an internal combustion engine and as aid for pump delivery at the time of high-speed activation of an actuator, etc.

■ Shock absorption of Water hummer and Surge pressureSuddenly shutting off a high-pressure and high-flow pipeline generates large impact pressure. In other cases mechanical shock to an actuator from external may cause fluid vibration and thus damage to equipment. The accumulator mitigates these shocks.

■Pump pulsation dampingPulse pressure in a single, dual or triple piston pump for high pressure operation makes control of a pressure device difficult. However, by using the accumulator, not only the trouble due to pulse pressure but also the knocking phenomenon due to smallness feeding from a cylinder of a machine tool etc. can be solved.

■ Leak compensationThe accumulator compensates for the pressure drop caused by a leak that may occur by keeping an actuator at a fixed position for a long time or by clamping something.

The hydro-pneumatic accumulator is a storage vessel for pressurized fluid that utilizes compressed gas. Energy from compressed gas makes pressured fluid discharge from the vessel. The bladder type accumulator has a soft rubber bag, that separates compressed gas and non-compressed fluid, and gas is charged into the bag. One of big characteristics of the bladder type accumulator is to have many other functions than energy storage.

■ Compensation in temperature changeThe accumulator reduces the pressure rise in closed pipe-lines under the burning sun and compensates for the pressure drop caused by fluid contraction in cold area.

■Hydraulic balancingBy using the gas pressure in the accumulator as a weight, cylinder friction leads vertical movement of a machine tool head or a television camera.

■Hydro-pneumatic shock absorptionThe accumulator serves as a spring for absorbing shock between the body and wheels of a vehicle. In addition, it can be utilized as a pneumatic spring for various squeeze rolls. The accumulator provides less-fatigue and high absorption efficiency of impact energy as compared to a spring.

■ Transfer barrierThis is the method to transfer the hydraulic pressure from one side to the other without mixing each fluid. In this method, the accumulator serves as a gas compressor or transfers corrosive fluid. In order to reduce the accumulator pressure change caused by charging or discharging fluids, the accumulator can also be operated with low differential pressure by increasing its gas chamber volume.

■ Fluid supplyThe accumulator is used for supplying lubrication oil in emergency or used as a portable oil lubricator.

●２

Title:中村工機-P02～08.ec6 Page:2 Date: 2014/12/15 Mon 09:14:44

Accumulator Volume

Calculation

P Ａ : Nomal Working Pressure (MPa･A)P Ｘ : Average Working Pressure (MPa･A)P Ｂ　　Max Allowable Pressure (MPa･A)P ｍM : Mass of Fluid in Line (㎏)υ : Flow Velocity (m/sec)q : Pump Delivery per a Revolution ( � /rev)F１ : Pump Coefficient (See the graph below.)

△ V : Available Discharge Volume of Acc. ( � )P１ : Precharge Pressure (MPa･A)P２ : Min Working Pressure (MPa･A)P３ : Max Working Pressure (MPa･A)n : Polytropic Exponent at Discharge time (Per Graph Below)m : Polytropic Exponent at Charge time (m=n-0.2)V１ : Accumulator Gas Volume ( � )

F１ : Pump CoefficientPulsation DampeningSurge AbsorptionEnergy Storage

F１Pump Type

0.6　single actingSimplex

0.25double acting0.25single acting

Duplex0.15double acting0.13single acting

Triplex0.06double acting0.10single acting

Quadruplex0.06double acting0.06single acting

QuintupleNote: Assuming the discharge/charge time as "1 or less", "n" is found from the average pressure value in the graph below. 0.02double acting

(1)The magnitude relationship of pressure should be 0.25 × (P3 or PB or Pm ) ≦ P ≦ 0.9 × (P2 or PA or PX ). (2) In case of n ＜ m in energy storage, make the value of “n” as “m” (but it should be over 1)

Polytropic Change & Exponent Graph(Check the exponent value from the discharge/charge time and the average pressure value.)

Example:1. On the assumption that the discharge time is 5sec and the average pressure is 5MPa, the polytropic exponent is 1.41.2. On the assumption that the charge time is 5sec and the average pressure is 5MPa, the polytropic exponent is 1.21.Note: Refer to the above broken lines. ●３

��

M ×υ２× (n － 1)V１=

2000×P１×��（） �

��

－ 1P Ｂ

P Ａ

q × F１

V１=1 －（）

１n

（）P χ

P１

P χ

P ｍ

Note : P１=0.6P Ｘ

P１× V１

P３

P２（）１m

△ V=P2

��

P３

P２（）��

－ 1１n

Note : In isothermal change, n=m=1.

△ V × P２× P３

P２（）１m

V１=P１

��

P３

P２（）��

－ 1１n 　n － 1

n

Discharge time (P3 → P2)Charge time (P2 → P3)Discharge time, Charge time (sec) →

　　

　　

　　

　　

P ２+P

３Av

erag

e pr

essu

re 　

　　

(MPa

･A)→

　　

　　

　　

　　

　２

Polytrop

ic e

xpon

ent n

, m→

３０

２５

２０

１５

１０

５

１or less

１or less

2 203 4105

6 7 8 9 3050

40 60708090100

200500

4003001000 2000 3000 4000

600 800 700 900

1.0

1.1(1.0)

1.2

1.3(1.1)

1.4(1.2)

1.5(1.3)

1.6(1.4)

1.7(1.5)

1.8(1.6)

1.9(1.7)

2.4(2.2)2.3(2.1)2.2(2.0)2.1(1.9)

2.0(1.8)

↑　↑　n　(m)

COM

MON

SYM

BOL

CAL

CULA

TION

FORM

ULA

LIM

IT


Exercise 1, Energy Storage :　Operate a 500kN press machine, that ram diameter is φ 200mm. The stroke is 115mm, the work time is 1.5sec and the idle time for removing the work is 2min. On the premise of the above, we compare two cases, Case 1 is to use a pump and a motor only and Case 2 is to add an accumulator to them. How will the size change? The answer is shown in Table 1.

＜Case 1: Pump and Motor only ＞＜＜ Case 1: Calculation ＞＞

　　　　　　　　　　　　　　　　　500 × 103 N Ram dia. 200mm, Required pressure= 　　　　　　=15.92 ≒１６MPa (Ram area=202 × 0.785=314� )　　　　　　　　　　　　　　　　　314� × 102

Fluid required for 1 stroke=314�× 11.5㎝=3,611cc=3.7 �　　　　　　　　　　　　　　　　　3.7�Fluid volume required in a second=　　　　=2.47 � /sec　　　　　　　　　　　　　　　　1.5 secFlow volume required in a minute=2.47 × 60=148.2 � /min ≒ 149 � /min　　　　　149 � /min × 16 MPaG　　　39.0Motor=�� ≒　　　 ≒ 47.6 kW ≒ 55 kW　　　　61.2 ×ηρ(Pump Efficiency)　　0.82

＜＜ Case 1: Result ＞＞The required fluid volume of the pump = 149 � /min , The required pressure = 16MPa or more, Motor capacity = 55kW

＜Case 2: Pump, Motor and Accumulator ＞　If an accumulator is added to the system, there are two approaches (Formula: Press power=Pressure × Ram dimension).　One method is to adopt the press cylinder with a larger bore in consideration of the pressure drop (P3 →P2) during fluid discharge(in case of the bladder type accumulator). Another method is to design the accumulator's max working pressure such that its minimum pressure of the accumulator becomes to 16MPaG at the end of discharge(in this case, the max pressure is designed as 21.5MPaG). Let us work on the latter example. In this case, the accumulator with the max pressure of 21.5MPaG and the pump with 21.5MPaG power are used together. The calculation for pump and motor size is as follows,＜＜ Case 2: Calculation ＞＞

　　　△ V × P2(P3/P2)1/m

V1=��　　　　　　　　　　　　　　P1 ｛（P3/P2）1/n － 1 ｝

Notes : ◎ On the pressure, convert (MPaG+0.1) into MPaA ◎ Refer to following item f as to P1

　　　3.7 × 16.1(21.６/16.1)1/1.2８

V1=��　=32.5�≒ 33�　　　13.4 ｛（21.6/16.1）1/1.85 － 1 ｝

　　　　　　　　　　　　3.7�Flow rate to accumulator=　　　=1.9�/min　　　　　　　　　　　　2min　　　　1.9� /min × 21.5 MPaGMotor=　　　　　　　　　　　　=0.82kW ≒ 1.1kW　　　　　　　61.2 × 0.82

＜＜ Case2: Result ＞＞The required pressure: 1.35 times bigger than Case1, The pump volume: 1/79 size of Case 1, The motor size: 1/50 size of Case 1.

＜ The sample procedure to select the accumulator model for exercise 1 ＞a. As the required pressure is 21.5MPaG, the model shall be G230 or T230 (Ref. pages 8 and 9).b. As the calculated gas volume is 33 � , the nominal gas volume is 30 � (Ref. pages 8 and 9).c. As the required fluid volume is 149 � /min, it is within the range of the max allowable discharge flow shown in the

G/T series (Ref. pages 8 and 9). d. If the fluid is mineral oil/water-glycol and the working temperature is under 80℃, the bladder material is NBR #20

(Ref. page 6). e. If a flange is used for piping, the oilport flange's type is OPE-D32 with a mating flange (Ref. page 16).

As a result of the above (a. ～ e.), the accumulator model shall be“G/T230-30-20-OPF-D32 with a mating flange”.

f. Confirmation of the Precharge pressure (P1)As the basic information, the higher the pre-charge pressure (P1) is, the bigger △ V increases. At the same time, P1 should be within the range of P1＜ 0.9 × P2. Taking into consideration the case that the fluid temperature may increase during operation, P1 shall be designed as consistently less than 90% of P2. If P1 becomes higher than P2, the bladder lifetime will be short.

　　Absolute temperature at prechargingP1=　　　　　　　　　　　　　　　　　× 0.9 × P２ �̃　　　　Max absolute temperatureWhen the value of P1 is 13.3MPaG, ⊿ V shall be 3.7 � .

　273+26=　　　　× 0.9 × 16.1=13.4 MPaA　273+50

●４

Table 1:Comparison table of Case 1 and Case 2Case 2Case 1

21.5MPaG16MPaGRequired pressure1.9�/min149� /minPump1.1kW55kWMotor33�NoneAccumulator

Title:中村工機-P02～08.ec6 Page:4 Date: 2014/12/17 Wed 17:53:10

●５

Exercise 2, Pulsation Damping :　The calculation formula to select the accumulator model for pulsation damping is as follows,

＜ Conditions Precedent ＞Details 2Details 1MeaningSymbol

3.1MPaA3MPaGPrecharge pressureP1

5.1MPaA5MPaGAverage working pressurePx

5.25MPaAPx ＋ 3％ = 5.15MPaGMax allowable pressurePm

Simplex & Single actingPump type-62rpmRevolution of pumpN32 � /minPump deliveryQ0.6Pump coefficientF1

32/62Q/NPump delivery per revolutionq1.51Average pressure = 5.1MPaAPolytropic exponentn

＜ Result ＞　The gas volume of the accumulator to control pulsation within ± 3% of the average working pressure is 26.8 � . For your information, the pump delivery per a revolution can also be calculated by checking the pump plunger size and its stroke.a. Refer to Exercise 1 for accumulator model selection.b. Refer to page 7 for the effects of pulsation damping.

q・F１・V１=

1 －（）１n

（）P χ

P１

P χ

P ｍ

=× 0.6 ×（）32

62

1 －（）1/1.5１5.1

5.25

=26.８�

5.13.1

Exercise 3, Surge Pressure Absorption :　The calculation to get the required gas volume of the accumulator for surge pressure absorption is as follows, (Purpose & Situation: Absorbing the surge pressure due to sudden closing of the valve in the pipe end.)

＜ Conditions Precedent ＞

Details 2Details 1MeaningSymbol700m-Total length of oil pipingL

216.3mm8B × Sch40(JIS : 216.3mm × Thickness 8.2mm)

External diameter of pipingD

199.9mm216.3mm�8.2mm�8.2mmInternal diameter of pipingd4500 � /minFluid volumeQ

0.63MPaA0.53MPaGNormal pipe-line pressurePA

1.23MPaA1.13MPaGMax allowable pressurePB

0.53MPaAP1 ≦ 0.9 × PA = 0.9 × 0.63MPaAPrecharge PressureP1

2.4m/sec4/ π× Q/d2 = 21.23 × 4500/199.92Flow velocityυ1.405Average pressure=(1.23+0.63)/2 ≦ 1Polytropic exponentn900kg/m3-Fluid specific gravityρ

＜ Calculation Formula ＞

＜ Result ＞The required gas volume of the accumulator is 205 � .

＜ Note ＞Please refer exercise 1 about the procedure of selecting the accumulator model.

　　π　　　　　πM=　d２･L･ ρ =　× (199.9 × 10 － 3)２× 700 × 900=19772㎏　　　4　　　　　4 (M: Mass of fluid in piping line (kg))

= = 205 �M ×υ２× (n － 1)

V１=2000×P１×

��（） �

��

－ 1n�１nP Ｂ

P Ａ

19772 × 2.4２× (1.405-1)

2000 × 0.53 ×��（） �

��

－ 10.2８８３1.23

0.63

＜ Calculation Formula ＞


Explanation of

Model Symbols

G　□　350 － 20　H－ 20 － OPF－ J－ 32 － CG　60M－MT－ S7

Mark for NAS cleanliness class in a servo circuitry etc. Select the class from 6, 7 or 8. If standard (not required the class), no mark.

　－ 25 to+80℃Low TemperatureNitrile rubber (NBR)10　－ 10 to+80℃Mineral oil, water glycolNitrile rubber (NBR)20　－ 10 to+90℃Gasoline, etc., Aromatic materialEpichlorohydrin (CHC)30　－ 10 to+90℃Phosphate esterButyl rubber (IIR)40　－　 5 to+120℃Chemical materialFluorocarbon rubber (FKM)28

Rubber materials

Types

Ref. pages 7, 8, and 9StandardHigh flow discharge (Ref pages 8&9)High flow typeHPoppetless (Ref. page 11)Screen typePTransfer of dissimilar fluid (Ref. page 12)Transfer barrier typeB

Surface treatment and Material

MaterialFluid typeContentsMarkFor mineral oil and water glycolParkerizing

Shell : Nickel plating Connection : Stainless steelFor Water, etc.

Nickel platingWShell&Connection: Stainless steelStainless steelSShell inside: PTFE coated Connection: Stainless steelPTFE coatingF

Accumulator Series

Ref. page 7Small volume typeMiniorator SeriesMRef. page 8Standard typeGeneral SeriesGRef. page 9Open top typeTwin Open SeriesTRef. page 10In-line typeDamper SeriesD

Nominal gas volume of the accumulator (� )Maximum working pressure (kgf/� )

●６

MT…Safety device for gas port.60M … Glycerol filled pressure

gauge for gas port.CG…Coreless type Gas Port (Ref. page 14).

��

If not specified,a standard gas valve will be provided.

Nominal diameter of a mating flange

Oilport flange model name(Ref. page 16).

��

A standard bushing (Rc connection) will be provided, if not specified.


M-SeriesMINIORATOR

●７

Max allowabledischarge flow

( � /min)F

E(mm)

B(mm)

D(mm)

UD(mm)

A(mm)

Mass（㎏）

Gas volume（�）

Max W.P.（MPa）

Dimensions

Model62Rc1/4－8560.5742322.00.115

20.6

M210-0.192Rc3/4358576.3942865.00.29　M210-0.392Rc3/4358576.3943766.30.5　　M210-0.5

260Rc3/41085107.912439812.51.0　　M210-1

◎ Maximum allowable discharge flow is designed to avoid the stopper's chattering phenomenon due to pressurized fluid. ◎ Maximum allowable discharge flow is designed in the case where the fluid material is mineral oil VG46.

■ Examples in Pulsation damping effects

(A) Without　　ACC.

(B) With ACC. (A) Without　　ACC.

(B) With ACC.

Ex.1 0.5�bladder type ACC. Ex.2 0.5�bladder type ACC.

M210ModelSpec.

20.6MPaMax. W.P

N２ gasGas type

0.25 × P3 ＜ P1 ＜ 0.9 × P2

(P1=Precharge pressure, P2=Min working pressure, P3=Max working pressure)

Prechargepressurelimits

Vertically (Oil side is downward)InstailationFluid = Oil : ParkerizingFluid = Water, etc. : Nickel platingNote: Stainless steel type is shown in page 13.

Surfacetreatment

M 210－1－20　　　　　　　Rubber　　　　　　　　　　　　　　Materials　　　　　　　　　　　　　　Nominal gas volume of accumulator (�)　　　　　　　Max working pressure　　　　　　　Series

Modelsymbols

��

20. (NBR)Mineral Oil

40. (IIR)Phosphate Ester

28. (FKM)Chemical Material


G-SeriesGENERAL SERIES

●８

G350G300G230G175ModelSpec.

34.4MPa29.5MPa22.6MPa17.2MPaMax. W.P.

N２ gasGas type

0.25 × P3 ＜ P1 ＜ 0.9 × P2

(P1=Precharge pressure, P2=Min working pressure, P3=Max working pressure)

Prechargepressurelimits

Vertically (Oil side is downward)InstallationFluid = Oil : ParkerizingFluid = Water, etc. : Nickel platingNote: Stainless steel type is shown in page 13.

Surfacetreatment

G 230－10 H－20　　　　　　　　Rubber　　　　　　　　Materials

　　　　　　　　Hi-Flow TYPE　　　　　　　　Nominal gas volume of the accumulator (�)　　　　　　　　Max working pressure　　　　　　　　Series

Modelsymbols

��

10. (NBR)Low Temperature20. (NBR)Mineral Oil30. (CHC)Aromatic Material40. (IIR)Phosphate Ester28. (FKM)Chemical Material

◎Refer to page 16 for flange connection.◎Maximum allowable discharge flow is designed in the case where the fluid material is mineral oil VG46.

Max allowabledischarge flow(�/min)

FE(mm)

D(mm)

C(mm)

B(mm)

A(mm)

Mass（㎏）

Gas volume（�）

Max W.P.（MPa）

Dimensions

Model

342Standard unit comes with a bushing Rc3/4 connection. As to a flange connection, refer to page 16.

10118　　

6410739191.2

17.2

G175－1120　　577152.4　　　－2.5168.3474183.7　　　－4

536204.7　　　－ 5

140015

232　　

106

89

6604412.0　　　－109336120.8　　　－20

14449637.2　　　－30195212853.1　　　－50231815264.7　　　－60

3600Connection is flangeOPF-S(Ref. to page 16)

108

6495911.3G175－10H9227620.1　　　－20H

143311136.5　　　－30H194114352.4　　　－50H230716764.0　　　－60H

1400

Standard unit comes with a bushing Rc3/4 connection. As to a flange connection, refer to page 16.

15

232　　

101

89

6625510.6

22.6

G230－109357919.0　　　－20

144612734.0　　　－30195417248.5　　　－50232020659.4　　　－60

3600Connection is flangeOPF-S or OPF-J(Ref. to page 16)

103

653709.9　　　－10H9269418.5　　　－20H

143714233.6　　　－30H194518748.1　　　－50H231122158.7　　　－60H


10

120　　64107

391101.229.5G300－1127　　577202.4　　　－2.5177.8458193.629.4　　　－4

514224.6　　　－5120　　64107391101.2

34.4

G350－1

140015

241.8

101

89

6476510.1　　　－1094510219.0　　　－20

145616334.2　　　－30196421949.3　　　－50232226260.0　　　－60

3600Connection is flangeOPF-J(Ref. to page 16)

103

633809.4　　　－10H93111718.3　　　－20H

144217833.5　　　－30H195023448.7　　　－50H230827759.3　　　－60H


T-SeriesTWIN OPEN SERIES

●９

■ Features :

�A large opening is provided on the top for ease of maintenance.�Because the bladder is pear-shaped to expand and contract easily, the excessive

deformation tends not to occur and the life span is long. �The bladder body doesn't have a seal structure, so special skill for maintenance is

not required. �In the way of customer's convenience the bladder can be replaced from both ports

in top and bottom. �The shell body has assembly structure without screw clamps, so customer is free

from stripped screws trouble in disassembly.

◎ Refer to page 16 for flange connection.◎ Maximum allowable discharge flow is designed in the case where the fluid material is mineral oil VG46.

Max allowabledischarge flow( � /min)FE

(mm)D

(mm)C

(mm)B

(mm)A

(mm)Mass（㎏）

Gas volume（�）

Max W.P.（MPa）

DimensionsModel

1400


15

232　

106

110

6734511.6

17.2

T175－109466220.4　　　－20

14579736.8　　　－30196512952.7　　　－50233115364.3　　　－60

3600

Connection is flange

OPF-S

(Ref. to page 16)

108

6626010.9　　　－10H9357719.7　　　－20H

144611236.1　　　－30H195414452.1　　　－50H232016862.6　　　－60H

1400


15101

107

6735610.3

22.6

T230－109468018.8　　　－20

145712833.8　　　－30196517348.3　　　－50233120759.0　　　－60

3600


OPF-S or OPF-J

(Ref. to page 16)

103

664719.6　　　－10H9379518.2　　　－20H

144814333.2　　　－30H195618847.7　　　－50H232222258.3　　　－60H

1400


15

241.8

101

657679.7

34.4

T350－1095510418.6　　　－20

146616533.8　　　－30197422148.9　　　－50233226459.6　　　－60

3600


OPF-S

(Ref. to page 16)

103

663849.6　　　－10H94111917.9　　　－20H

145218033.1　　　－30H196023648.3　　　－50H231827958.9　　　－60H

355.6108110

91811043.0

11.8

T120－40114413661.0　　　－58136416279.0　　　－801968234127.0　　　－1202666316183.0　　　－180

355.6103105

91815541.0

17.2

T175－40114419258.0　　　－58136422775.0　　　－801956323120.0　　　－1202670439170.0　　　－170

406.41001022046423167.0TL175－1702652549222.0　　　－230


OPF-S or OPF-J

(Ref. to page 16)

355.6103105

91817737.0

22.6

T230－40114422254.0　　　－58136427070.0　　　－751956391112.0　　　－1202670535164.0　　　－170

406.41001022056531157.0TL230－1602662689213.0　　　－220

355.6103105

91821435.0

34.4

T350－40114426751.0　　　－58136432166.0　　　－701950459103.0　　　－1002700636155.0　　　－160

406.41001022056609152.0TL350－1602662792205.0　　　－220

■Model symbols :

T 175 － 10　H － 20RubberMaterials

Hi-Flow TYPENominal gas volume of the accumulator (� )

Max working pressureSeries

��

10. (NBR) Low Temperature20. (NBR) Mineral Oil30. (CHC) Aromatic Material40. (IIR) Phosphate Ester28. (FKM) Chemical Material


D-SeriesDamper series

(In-line type) Accumulator

●１０

Flow

Across Flats 55

■ Features :

● Because the fluid directly flows along the surface of the bladder, the bladder can absorb high frequency pulsations.

● A valid and feasible model for prevention of water hammer, surge pressure and noise, etc.● Because the accumulator is directly installed into pipe-line, customer can save the space and this alleviate

concern about contamination due to fluid residence.● The bladder body doesn't have a seal structure, so special skill for maintenance is not required.

■Model symbols :

D 215 － 02 － 20RubberMaterials

Nominal gas volume of the accumulator (� )Max working pressure

Series

��

20. (NBR) Mineral Oil40. (IIR) Phosphate Ester28. (FKM) Chemical Material

Max allowableflow rate(�/min)

D(mm)CB

(mm)A

(mm)Mass（㎏）

Gas volume（�）

Max W.P.（MPa）

DimensionsModel

14080　Rc 1 �1313288.00.1921.0

D215-02

420154　　 Flange 40A　　 Connection16740033.01.2D215-1.5

◎If flange connection is applied, the position of the bolt-hole of each flange is different in rotation direction. 　The mating flanges and the seal parts will be provided.

■Example in Pulsation damping effects

(A) Without　　ACC.

(B) With ACC.


P-TypeScreen Type Accumulator

●１１

　Screen type can be applied to G series and T series. Screen type has a plate with many small holes to allow fluid to pass through, in lieu of a poppet valve placed at the oil port. Max allowable precharge pressure is 0.75MPaG and the bladder of this type is free from damage due to a poppet even if the fluid pressure will be under the precharge pressure or be same to atmosphere pressure. This type is widely used for surge pressure damping in a water pipeline at low-pressure use or in pipelines in petrochemical industries, etc.

Screen type in General series

■Model symbols :

Max flow rate(�/min)

FE(mm)

D(mm)

C(mm)

B(mm)

A(mm)

Mass（㎏）

Gas volume（�）

Max W.P.（MPa）

Dimensions

Model


Bushing height 10

(Ref. to page 8)

118　64107

39191.2

3.0

G30－1P120.0577112.4－2.5P168.3474183.7－4P

536204.7－5P

700Connection is

OPF-S. (Ref. page 16)

232　108

89

6495911.3G30－10P9227620.1－20P

143311136.5－30P194114352.4－50P230716764.0－60P

110

6626010.9T30－10P9357719.7－20P

144611236.1－30P195414452.1－50P232016862.6－60P

355.6136416279.0T30－80P1968234127.0－120P2666316183.0－180P

◎ Max flow rate is calculated under the situation where the pressure difference between the accumulator and the pipe line is 1.18MPa.

◎ Max flow rate is designed in the case where the fluid material is mineral oil VG46 at 28℃.

G 30 － 10 P － 20 －　

RubberMaterials

P-Screen typeNominal gas volume of the accumlator (� )

SeriesIf the Twin Open Series is required, indicate “T”.

��


�For a bushing connection, specify Rc diameter.�For a flange connection, specify the standard and

nominal diameter of it.

Max working pressure (3.0 MPa)


B-TypeTransfer Barrier Type

Accumulator

●12

　Transfer barrier accumulators are used to transfer pressure between different types of fluid, for example, the pressure between oil and water, clean oil and contaminated oil, liquid and gas, etc. A perforated tube is installed into the bladder to prevent the bladder from damage due to the fluid's direct contact with the interior of the bladder. Concretely speaking, this type accumulator is used to convert oil pressure to water pressure and/or supply oil to a compressor bearing, etc.

Transfer Barrier Type in T series■Model symbols :

T 175 － 20 B － 20 －　

RubberMaterials

“B”means Transfer Barrir TypeNominal gas volume of the accumulator (� )

SeriesIf the Gneral Series is required, indicate“G”.

��


�For a bushing connection, Rc3/4 is provided as standard for both gas and oil port sides.�For a flange connection, specify the standard

and the nominal diameter of the flange.

Max working pressure

FE(mm)

D(mm)

C(mm)

B(mm)

A(mm)

Mass（㎏）

Gas volume（�）

Max W.P.（MPa）

Dimensions

Model

Reference dimension,ASME 150LB 1 � B RF

55232106

1109546120.8

17.2

G175－20B14659637.2　　　－30B197312853.1　　　－50B233915264.7　　　－60B

115

9516220.4T 175－20B14629736.8　　　－30B197012952.7　　　－50B233615364.3　　　－60B

90355.6103137422775.0T 175－80B1966323120.0　　－120B2680439170.0　　－170B

◎In case where the mineral oil VG46 flows at 200� /min, the pressure loss of the perforate tube shall be about 0.08MPa.

◎The bladder's compression ratio shall be within (0.2P3≦P1≦0.9P2) or within (V3≧0.2V1, V2≦0.9V1).


M.G.T. SeriesStainless Steel

Accumulator

●１3

　Recently, accumulator came to be used for not only oil system but also water/special liquid system being operated by high purity washing water, high cleanliness chemical fluid, etc.　For such applications, a stainless steel accumulator is most appropriate.

■ Features :

� The material is stainless steel that has high anti-corrosiveness such as SUS304, SUS316L, etc.� Customer can maintain a high cleanliness level in the lubricating system, the hydraulic system, etc. by using this

accumulator. � The shell is designed under JISB8358 and is non-weld integral structure made from seamless tube.� Titanium (TB480H) bladder type accumulators are also available. � The special model with the max working pressure up to 34.4MPaG can be supplied.

◎The dimensions of E and F written in the above table is our standard size. If other standard such as ASME, API, JPI or DIN or other special material is required, please let us know the specification.

◎Please let us know your desired allowable flow rate.

FE(mm)

D(mm)

C(mm)

B(mm)

A(mm)

Mass（㎏）

Gas volume（�）

Max W.P.（MPa）

DimensionsModel

Rc1/4－60.574※ UDRef.

page 785

23220.11520.6　

MS210－0.1


3576.39428650.29－0.33766.30.5－0.5

1010011539810.51.0－1

114.364107

39191.013.8　

GS140－157712.52.4－2.5

15177104500213.4－4558244.4－5

1523210689

6563512.0

　7.0

GS70－109294821.3－20

14407638.7－30194810156.1－50231412067.6－60

15232101104

6653711.5

　7.0

TS70－109385020.8－20

14497738.2－30195710355.6－50232312367.1－60

A flange connection is OPF-S (Ref. page 16).406.4105107

1323162101.06.0

TSL60－1001938240167.0－1702578320237.0－240

Stainless Steel Type in G Series■Model symbols :

G S 70 － 50 － 20 －　

RubberMaterials

Nominal gas volume of the accumulator (� )Max working pressure

Series　M － Miniorator Series　G － General Series　T － Twin Open Series

��


For flange connection, specify the standard and the nominal diameter of flange.

“S”means Stainless Steel Type


Pressure gauge

Bleed plug Coreless valve MT or SP(N2 gas suppiy port)

Stop valve

set screwAccumulator conenecting port

REF. 69.5

REF.

160

Accessories on gas side

●14

1. Coreless type gas port

2. Charging Assembly :

�Charging Valve　(VR type)

Circuit diagram

Bleed plug

Stop valve

TV8(8V1)(N2 gas supply port)

Coreless valve

Safety device

Connecting to accumulator, 7/8"-14UNF

Glycerol filled pressure gauge

Hose connection

Connecting to accumulator

TV8(8V1)

�Charging Hose Assembly

■Model symbols :

Note: Only a charging hose assembly is required when the coreless type gas port is being installed. In other words, the charging valve assembly is not required when the coreless type gasport is being installed.

G 230 － 50 － 20 － CG

Rubber materialsNominal gas volume of the accumulator (� )

SeriesMax working pressure

Max. scale of pressure gauge － Safety unit

Pressure test valueMax working pressureType52MPa34.4MPaCG

Working presure rangeStandard max scale value0 ～ 18MPa25MPa0 ～ 25MPa40MPa0 ～ 34.4MPa60MPa

Melting TemperatureSafety-unit Type105 ± 5℃MTStop plugSP

�Coreless type gas port (Approved by the Japanese High Pressure Gas Safety Act of METI)

�Glycerol filled pressure gauge

�Not required for 10 or more liters accumulator because this is being installed in the bladder assembly.

Full length : Approx.2000

G1/4 W22-14 W23-14for JIS Nitrogen bottle-Type A for JIS Nitrogen bottle-Type B

Standard length

Max working pressure

Charging Hose Type

2m14.7MPaTS1502m39.2MPaTS400

�Caution in the case where the charging pressure is extremely low pressure.When the charging pressure toVR type gas valve is less than 1MPa, there is possibility not to be able to charge gas into an accumulator due to the cracking pressure of the check valve (core) of the charging valve.Therefore, if the charging pressure is less than 1MPa, please let us know before you order. The charging valve (VRZ type) for extremely low pressure is recommended.If you have any questions, please feel free to contact us.


●１５

■Model symbols :

Note: If the charging gas pressure is less than 1MPaG, please let us know before you order.

3. Melting plug :

Melting plug is a safety device to protect the accumulator from abnormally high temperature environment.

■ Features :

●Melting plug doesn't have moving parts, so it is dependable as a safety device.●Because Melting plug is installed separate from the gas supply valve seat, there is not damage due to

charging gases.●Even if the fuse is melted by fire disaster, the valve-guard prevents the melted piece from blasting off.●Because Melting plug is being incorporated into the valve stem of bladder, this is renewed by replacing the

bladder and no extra space is required.●Melting plug is safe against external shocks, etc.

　Standard melting temperature is 105 ± 5℃. The temperature is designed for the plug to start melting at the time when the accumulated pressure increases higher than the accumulator's max pressure. 　After that, the accumulated gas is discharged from the plug hole and controlled not to greatly exceed the max pressure. 　Please take care that there is a possibility the plug starts melting during operation in high temperature environment over 80℃, and it leads gas leak. In this case, we recommend to use Melting plug for high temperature, that starts melting at 180 ± 10℃.　To select appropriate safety device, please let us know before you order.

Circuit diagram

Connecting to accumulator, 8V1 (TV8)

Charging Valve↓

Charging Hose Assembly↓

－

Length　　Leave blank if it is standard (2m).　　Enter the no. of length you desire.

Indicate the rated pressure,(kgf/� )-150, 400

Hose Type

Max scale of pressure gauge-(indicated in MPa.)(Pressure gauge size is AT 1/4 ×φ60)

Charging Valve type: VR-type for an accumulator with a coreless type gas valve

TS ※×※

Melting plug

Fusible metal

Gas valve assembly

Gasket

N2 gas

VR ※

ChargingHose assembly

Circuit diagram

Connecting to accumulator, 8V1 (TV8)

ChargingHose assembly

PressuregaugeBleed

plug


OPF SeriesOIL PORT FLANGE

●１６

　If a flange connection is applied, we recommend to choose it from models shown in the followings.

■Model symbols :

G 230 － 10 － 20 － OPF － B20　(Require a mating flange.)

Please indicate the oil port flange model name if applied. In addition, please let us know whether a mating flange is required or not. Blank means to select our standard bushing(Rc3/4).

Rubber materialNominal gas volume of the accumulator (� )

Accumulator series.Maximum working pressure.

※ All oil port flange comes with seal parts.

Oil port flange

Mating flange

StandardMatingflangeGHe

(mm)T

(mm)d２

(mm)d１

(mm)C

(mm)B

(mm)A

(mm)Nominal

dia.ModelNominalvolumePress

JISB2291

SSA32M12G40162843.231.544　56φ 11832（１�B）

OPF-S

10H～60H

and40～

230

20.6MPa

SSA40M16G50183649.137.544　65φ 13540（１�B）SSA50M16G60203661.147.544　73φ 14450（２B）SSA65M20G75224577.160　45　92φ 18565（２�B）SSA80M22G85254590.071　45103φ 20080（３B）

Nakamura in-house standard

NHFA32M24G80184343.232　44110□ 15332（１�B）

OPF-H22.6MPa

NHFA40M24G80204349.140　44110□ 15340（１�B）NHFA50M24G80234361.150　44110□ 15350（２B）NHFA65M24G80284377.164　44110□ 15365（２�B）NHFA80M24G80314390.071　44110□ 15380（３B）


NHFA32JM27G65184443.232　45116□ 17632（１�B）

OPF-J34.4MPa

NHFA40JM27G65204449.140　45116□ 17640（１�B）NHFA50JM27G65234461.150　45116□ 17650（２B）NHFA65JM27G65284477.156　45116□ 17665（２�B）NHFA80JM27G65314490.056　45116□ 17680（３B）

For high flow (H type) and 40 to 230 liter accumulators

Oil port flange

Mating flange

For 1 to 60 liter accumulators

StandardMatingflangeHGT

(mm)d２

(mm)d１

(mm)C

(mm)B

(mm)A

(mm)Nominaldia.mmModelNominal

volumePress

Nakamura in-house standardNHA15G25M122522.216　2845　8815（�B）

OPF-A1 ～ 5

20.6MPa

JISB2291

SHA20G30M102227.720　2845　8820（�B）SSA25G35M122834.524　2848　8825（１B）

Nakamura in-house standardNHA15G25M122522.216　2845　8815（�B）

OPF-B10 ～ 60 JISB2291

SHA20G30M102227.720　2845　8820（�B）SSA25G35M122834.525　2848　8825（１B）SSA32G40M122843.231.5325611832（１�B）SSA40G50M163649.135　326511840（１�B）


NHA50G50M163661.135　407514450（２B）NFA15G25M122522.216　2845　8815（�B）

OPF-C1 ～ 5

34.4MPa

NFA20G30M122527.720　2848　8820（�B）NFA25G35M163134.524　325611825（１B）NFA15G25M122522.216　2845　8815（�B）

OPF-D10 ～ 60

NFA20G30M122527.720　2848　8820（�B）NFA25G35M163134.525　325611825（１B）NFA32G40M163143.231.5326511832（１�B）NFA40G50M203949.435　407514440（１�B）NFA50G60M204761.135　488415650（２B）

◎ Please let us know whether a mating flange is necessary or not.

◎ Please let us know if you need the product in other standard such as ASME, API, JPI, DIN etc. or specify the material.


●１７

BAB SeriesHYDRO-LUNG

■Features :

● Preventing pollution of the hydraulic fluid● Preventing evaporation of hydraulic fluid such

as water glycol

Fig.1 Example of Hydro-Lung use

HU oil level on cylinder ascent

Directional control valve

Breather

Hydro-Lung

HL oil level on cylinder descent

How to select the model（1） Calculate the max displacement of the hydraulic fluid in the oil reservoir

　　 π Vk =　　　d2s・ 10 － 6

　　　4　　　Vk : Max displacement of hydraulic fluid (�) 　　d : Diameter of the piston rod (mm)　　s : Cylinder stroke (mm)

（2）Calculate the max flow rate at the time of the displacement (Vk).　　　Vk　Q0 = 　　・60　　　Tc　　　Q0 : Max flow rate ( � /min)　　Tc : Operating time of the cylinder (sec)

（3） Comparing the calculated max flow rate with the allowable flow rate, decide the selection method of the accumulator.

Q0 ≦ QQ : Max allowable flow rate ( � /min)

　As a result, when Qo is less than Q, it is needed to select a hydro-lung which maximum displacement is adequate to Vk (Ref. the below model list). But if Qo is more than Q it is better to increase the number of hydro-lungs.

　As Fig. 1 Example of Hydro-Lung use, the oil level changes at the same amount as the piston rod volume according to the hydraulic cylinder operation. At the same time, Hydro-lung absorbs the rise and fall in the air chamber. In other words, the bladder of Hydro-lung expands along with increase of the oil-level and constricts according to decrease of the oil-level. 　Because a breather valve is equipped, Hydro-lung is effective at the situation also where the oil level greatly changes due to supplying operation oil or replacing devices. 　Concretely speaking, the bladder of Hydro-lung constricts along with decrease of the oil-level. After that, the bladder absorbs atmosphere from the vacuum valve ② via filter ③ . Conversely, the bladder expands along rise of the oil level or along increase of the pressure in the air chamber. After that, the air discharges to outside through the relief valve ① .　In addition, Hydro-lung can prevent the oil reservoir from the contamination due to external atmosphere since the inside is isolated from the outside.

Fig.2 Breather

Breather

Rc3/4 to tank

Max W.P. (MPa)

Mass (kg)

D(mm)

C(mm)

B(mm)

A(mm)

Max allowable flow rate Q ( � /min)

Max volume of breath ( � )

Model

0.03

6114.321738416747.10.8BAB 　19114.321757235547.11.6BAB 2.5

10165.221744222547.12.4BAB 　416216.3259635376152.6 6.0BAB 1024216.3259925666152.611.7BAB 2038216.325914461187152.621.0BAB 3052216.325919321673152.632.0BAB 50


●1８

Accumulator stand

　We design and manufacture accumulator stands that several accumulators are put together on in addition to supplying a single accumulator.　Accumulator stands equipped with not only accumulators and the piping but also stop valves, pressure gauges, pressure switches, other hydraulic devices and stainless steel pipes can be provided. 　For example, the accumulator stand with deck stand is designed to check the gas pressure or to maintain the accumulator safely and the accumulator stand with adjusting bolts is designed to replace bladder and maintain the accumulator assembly without using hanging tools or machines such as cranes.　The accumulator stand is completely made-to-order, so it is possible to design it in single line, double lines or etc. as customer demand in consideration of customer's installation space.

● Following pictures are sample model.


●１９

Accumulator stand photos supplied in past

Accumulator stand with 12 sets of 220L accumulator (31MPa)



Gas cylinder stand with 8 sets of pressure vessel for N2 gas (20MPa)


PA SeriesPiston type accumulator

●２０

　We started to produce piston type accumulators with our own technology in 1967 and after 3 years, ones of 150 liter was supplied to Nippon Steel Corporation Oita factory for their slab continuous casting machine.　Since then they have been widely used by many customers and applications such as the Ministry of Defense in Japan, power plants, hydraulic controls, etc.

■ Features :

�Because low friction packing is used, the slide friction is small.�There is no limitation in the ratio between N2 gas

precharge pressure and hydraulic pressure. �Large gas volume type and High pressure type

can be provided.

■Model symbols :

With a sensor

PA 230 － 20 － 20 － LS

Seal materials…20. (NBR) for mineral oil　　　　　　　28. (FKM) for Phosphate ester

Nominal gas volume of the accumulator ( � )Max working pressure

Piston type accumulator

Maxflow rate( � /min)

FE(mm)

D(mm)

C(mm)

B(mm)

A(mm)

Mass(㎏)

Gas Volume( � )

Max W.P.(MPa)

Dimensions

Model

990Standard size is φ 49.1 (40A) or less.Please letus know if it is 50A or more as special.

36241.82

8795316020

22.6PA230－20

156222040　　　－402200355.616138049060　　　－60

1860605100　　　－100◎ Please let us know the use condition and the operating fluid.◎ As a special specification, large flow rate type can also be provided.◎ The accumulator with ASME stamp, CE (PED) mark or Chinese certification can be manufactured.◎ The accumulator available to flame retardancy oil or chemical fluid can be provided.◎ Equivalent accumulator to cleanliness class NAS6 can be provided.


●２１

LS SeriesPiston type accumulator

with a sensor

　A sensor is being installed inside the piston type accumulator to comply with hydraulic systems electronically controlled, and it outputs electric signals continuously and detects the position of the piston of the accumulator.

■ Features :

�Detecting the position of the piston continuously. �Because the available discharge amount can be confirmed by

detecting the piston position, it is possible to forecast the maintenance inspection time.�The sensor is placed at a non-pressurized area, so the life is long.�Because the sensor is absolute type, Zero-point setting and Zero-

point correction are not necessary.�Output signal complying to voltage and current is analog, so the

piston position can be easily detected.�The output signal can be indicated in a digital counter and the signal

data fetched to personal computers can be utilized to high level control system.�A high level control is achieved by using the sensor in combination

with a pressure transducer.�It is possible to measure fuel discharge amount in detail.�A sensor can be applied to all piston type accumulator (Ref. P20).

Controller

Output signal

Power source

Example 1 Example 2

ACC

Example 1 Example 2

ACC

Controller

Power source

Voltmeteror

Ammeter

In case of digital output

In case of　analog output

A/D converterDigital counter,personal computer,

etc.ACC

Controller

Power source


22

HYB SeriesN2 ɡas booster

　N2 gas booster has high energy saving effect. Our piston type accumulators that have a long application history and high reliability that we are proud of are being installed in it as an compressor.

Circuit diagram

■Features :

◦Compact portable type◦Low noise◦Small power consumption◦Cooling water is not required.◦Easy maintenance with simple structure◦Less expensive than conventional compressors

t°

N2

23

HYB SeriesN2 ɡas booster

ES Type

■Model symbols :HYB 10 − ES 2 − 24 − 7.5 × 220V

Power source voltage (※Please offer this infomation in advance.)Electric motor output (kW)

Maximum N2 gas generating pressure (MPa)(Max W.P of Hyd. pump Minus 1.5)

Design number

Booster (Compressor) volume (ℓ)Hydraulically driven booster unit

Type　ES:Electrical control type

Reference information from proven specification (Standard model)ModelSpecification ES

Booster Unit

Motor output/cycle kW/Hz 7.5/60 (7.5/50)Max generated gas pressure MPa 24Dimensions mm 750 × 1160 × 1590Mass kg 600

HydraulicPump

Max working pressure MPa 25.5Delivery ℓ/min 10.6Revolution rev./min 1800 (1500)

Compressor Type - Piston typeVolume ℓ 10

Note: This product is not suitable for long time continuous operation because this is for charging N2 gas into our standard accumulator.If you intend to use this product in other purpose than the above, please let us know before you order.

24

FHN SeriesAccumulator Stop Valve

　Ever since we started to distribute FHN series as accumulator stop valve in 1985, this product is well-known for many achievements and the reliability.

※ OPF-E and OPF-H are special type flange.※ If FHN65S is applied to accumulators with 10 to 60ℓ capacity, it is

connected to OPF-E-40 by using a spacer additionally.※ When the accumulator is connected to a drain port, two kinds

of joint of a bite type joint and a weld type joint are our standard selection (Ref. pictures at right side). Please specify either of them as you place an order.

■Features :

FHN32S＆FHN65S FHN32L

Bite type fitting (K) Weld type fitting (W)

◦Compact design with small number of components.◦Directly connecting to an accumulator is possible.◦Balance structure and a bearing make operation to open and shut easy even at high pressure.◦ It can be used both as a stop valve and a throttle valve.◦Chattering will not occur because the main valve is being screwed to the valve rod.◦By using an accumulator joint, the bladder can be replaced without removing an accumulator from the system.◦Stainless steel (SUS304) type can be provided.

DimensionModel

d(㎜)

A(㎜)

B(㎜)

C(㎜)

D(㎜)

E(㎜)

F(㎜)

G(㎜)

H(㎜)

I(㎜)

J(㎜)

K(㎜)

L(㎜) M N

(㎜)P

(㎜) Q R(㎜)

Applicableaccumulator Remarks Max W.P.

(MPa)

FHN32S φ30 217 111 106 104 52 77 − 155 − 48 70 18 G¼ 88 75 M16 55.5 10〜60ℓ Connect to OPF-E-40

34.4FHN65S φ56 320 200 120 153 80 114 − 210 − 48 98 38 G¼ 88 110 M24 122.0HF＆40〜

230ℓ

Connect to OPF-H

FHN32L φ30 217 111 106 104 52 77 104 154 50 48 70 18 G¼ 88 − − 55.5Connect to

accumulator directly

25

FHN SeriesAccumulator Stop Valve

Circuit diagram :

Connection by OPF Connection by an accumulator jointDirect Connection to accumulator

ACC

To drain port (G1/4)

To main port

■Model symbols

Example of use:

FHN 32 S − 20 − N − F1-1/4B − K −S7

Mark for NAS cleanliness class.If standard (not required the class), no mark.

Connection parts to a drain port N : No mark (prepared by customer) K : Bite type pipe joint W : Weld type pipe joint

Connection parts to a main pipe N : No mark (connecting to a inline block arranged separately) F1-1/4B : Weld type mating flange (Connection size shall be written after “F”.)

Connection parts to an accumulator N : No mark

◦ In case where FHN32L is applied.◦ In case where a mating flange (standard) or an accumulator joint is applied.

Seal parts material 20 : NBR 28 : FKM

Connection measure S : Connecting to a flange L : Connecting directly to an accumulator

The port size of the stop valveAccumulator stop valve

※ The standard connecting way is to use a mating flange.However this time, we would like to show the way to connect an inline block by using below picture.

26

Hiɡh Pressure Gas Cylinder

　We design and manufacture high pressure gas cylinders by taking advantage of the proven know-how that we have cultivated in accumulator manufacturing. Concretely speaking, cylinders we supplied is 1 to 500 liter in capacity and the max pressure is 49MPa. The material of cylinders is not only carbon steel but also stainless steel.　The cylinder has many uses, for example, it has been used successfully as a receiver tank for piston type accumulator or as pressure vessel of various gases. If the cylinder is used as a receiver tank, it is possible to provide the unit composed by a piston type accumulator and the cylinder.　The cylinder complying with the Designated Equipment Inspection Regulation of High Pressure Gas Safety Act can be supplied. And it is also possible to provide cylinders designed by ASME or by various classification survey.

Note:1. The high pressure gas cylinder is different from the vessel under the Cylinder Safety Regulations of High Pressure

Gas Safety Act.2. This product is completely made-to-order, so it is possible to design it as customer demand.

27

NAKAMURA KOKI REQUEST FORM for selecting accumulator

Please fill out 1 〜 4 for the accumulator selection.

Please select the intended use of accumulators from A 〜 D and fill in the blanks.

4. Specification （a 〜 e）

Date:

Your company name

Contact person TelE-mail

System name・Installation position

Intended use of accumulators A. Energy Storage B. Pulsation Damping C. Surge Absorption D. Other

Type of Accumulators

□ Bladder TypeA rubber bag is used to separate N2 gas from liquid. It is used to variety applica-tions such as energy storage by accumulating and discharging energy, pipe pulsa-tion absorption, surge absorption and etc. Our accumulators, not only bladder type but also piston type, are of help in energy saving and improving equipments.

□ Piston TypeA piston is installed to separate the pressurized liquid and the gases. This accu-mulator is reliable without sudden accidents such as the bladder damage.　The especial difference to the bladder type is that a super large capacity model and ul-tra-large flow model can be manufactured in this piston type.

1. Inspection, Standard, etc.□Unnecessary

（Nakamura Koki internal standards）

□ High Pressure Gas Safety Act in Japan

□ASME

□China standard

□CE-MARK

□Others（）

A. Energy Storage

Available Discharge Volume of Acc. Δ V ℓ

Max Working Pressure P3 MPa

Min Working Pressure P2 MPa

Precharge Pressure P1 MPa

Discharge Time Tn sec

Charge Time Tm sec

Required Discharge Flow. Q ℓ/min

※D.Other

C. Surge Absorption

Normal Working Pressure PA MPa

Max Allowable Pressure PB MPa


Fluid Density ρ kg/m³

Inside Diameter of Pipe d mm

Length of Pipe L m

Flow Rate of Fluid Q ℓ/min

B. Pulsation Dampening

Pump Type

□Plunger [ ]cylinder□Single acting□Double acting□Diaphragm

□vane □gear □

Average Working Pressure Px MPa

Setting Pulsation Rate - ％

Max Allowable Pressure Pm MPa


Pump Delivery Q ℓ/min

Revolution of Pump N rpm

2. Operating ConditionNormal Working Pressure MPa

Design Temperature ℃

Normal Working Temperature ℃

Working Temperature Range 〜　　　　℃

Working Fluid

Installation Site □ Indoor □Outdoor

Installation Direction □Vertical □Horizontal

3. The Bladder MaterialMaterial Used Fluid Temperature range

□ 10（NBR）Nitrile rubber For low temperature -25 〜 + 80℃

□ 20（NBR）Nitrile rubber Mineral oil, Water glycol -10 〜 + 80℃

□ 30（CHC）Epichlorohydrin Gasoline・Aromatic material -10 〜 + 90℃

□ 40（IIR）Butyl rubber Phosphate ester -10 〜 + 90℃

□ 28（FKM）Fluorine rubber Chemical material, etc - 5 〜 +120℃

※ If the material of rubber is unknown, please let us know the working fluid and the working temperature range.

a. Connecting parts in the oil side

□BushingConnection threaded port size[ ]

□ Oilport flange model name （Ref. P16）[ ]Mating Flange [ applied・not-applied ]

□ Oilport Flange’s Standard and the size[ ]

□ Without connection parts

□Others [ ]

※ Other special specifications :

b. Parts/device in the gas side

□Coreless type gas valve（Nakamura Koki Standard）

□Core type gas valve

□Coreless Type Gas PortPressure Gage Unit[ ]

□Flange（Standard name・size）[ ]

c. Safety device

□Melting Plug（Nakamura Koki Standard）

□Rupture Disk Type

□Special[ ]

d. Name Plate

□ Nakamura Koki Standard Name Plate

□Specified Name Plate（Please attach specifications）

e. Paint

□Unnecessary （Parkerizing）

□Nakamura Koki StandardUndercoating：Synthetic resinFinal coating：Phthalic acid resinPaint color：Munsell N7

（JPMA color codes N-70）

□Special（Please attach specifications）

※CAD data and the capacity calculation program, you can be downloaded from our web site.

Our entry column Recommended Model Notices Sales office・the person in charge

Selection Date

28

NAKAMURA KOKI CALCULATION FORM for energy storageSystem Name・Use Place

Date:

◎Please use the absolute pressure in the calculation （Absolute pressure （MPaA） = Gauge pressure （MPaG） + 0.1 ）.

Available Discharge Volume of Acc. Δ V ℓ The discharge in the pressure change from P3 to P2.

Max Working Pressure P3 MPaA The maximum pressure when the fluid accumulates

Min Working Pressure P2 MPaA The minimum pressure when the fluid discharges

Precharge Pressure P1 MPaA ①

Average Working Pressure Px MPaA （ P3 + P2 ）/ 2

Discharge Time Tn sec Time to discharge the fluid by ΔV liter from the accumulator

Charge Time Tm sec Time to accumulate the fluid by ΔV liter to the accumulator

Polytropic Exponents at Discharge Time n②

Polytropic Exponents at Charge Time m

Accumulator Gas Volume V1 ℓ ③

① Calculation for determining the precharge pressure value

※ Please apply the value of a or b.a. P1 = 0.9×P2（ Min working pressure）

b. When there is temperature change, the below formula is applied.

　　 273+Min temprature（℃）P1 ＝　　　　　　　　　　　 ×0.9×P2（Min working pressure）　　 273+Max temprature（℃）

The precharge pressure range : 0.25×P3 ≦P1 ≦ 0.9×P2

◎ If the precharge pressure is higher than the value calculated at the above, accumulator capacity becomes smaller but it is not recommended because the life span of the bladder becomes shorter.

②Polytropic Exponents Check the discharge time（Tn）, the charge time（Tm） and the average working pressure（Px） and confirm the polytropic exponent at discharge time（n） from the graph shown in page 3. The polytropic exponent for charge time

（m） is n- 0.2. （ To compensate the shortage of gas volume （V1）, the value of m is 0.2 less than the value of n.）

Ex. P2 = 16.1MPaA P3 = 21.6MPaA Average working pressure=18.85MPaAIf Tn is 1.5sec, "n" is confirmed as 1.85 by the graph shown in page 3.If Tm is 120sec, "m" is confirmed as 1.48-0.2=1.28 by the graph shown in page 3.

※ In the case of isothermal change, n = m = 1. ※ In the case of n < m, make the value of "n" same as "m".※ If the value of m is unclear because the change time is not fixed, we recommend to make the value of m as one（1）

to put flexibility into the capacity.

③Accumulator Gas VolumeCalculation Formula

<Energy Storage> V1＝ΔV×P2× P3

P2（　）1ｍ

P1×P3P2（　）

1n－1｛　　　｝

＝＝ℓ　　 × ×

MPaAMPaA（）1/

ℓ× （）

1/｛｝－1MPaA

MPaAMPaAMPaA

※ A distinctive idea such as "Gross efficiency of accumurator" defined in other maker's own right is not included in our calculation formula.

Calculation Example Assume that we select accumulator being installed in hydraulic pressure pipe line as energy storage. By using the following calculation, we confirm the accumulator gas capacity and confirm the max allowable discharge flow. The detailed specification is shown in the below table.Conditions Precedent: Discharge time = 1.5 sec, Charge time = 120 sec, Ambient Temperature = 26 ℃, Temperature during operation = 50 ℃Available Discharge Volume of Acc. ΔV 3.7ℓ Precharge pressure （P1）:

　　　　273 ＋ 26P1 ＝——————×0.9 × 16.1 ＝ 13.4MPaA　　　　273 ＋ 50

Max Working Pressure P3 21.6 MPaAMin Working Pressure P2 16.1 MPaAPreharge Pressure P1 13.4 MPaA Accumulator gas volume （V1）:

V1＝ΔV×P2×

P3

P2（　）1ｍ

P1×P3

P2（　）1n－1｛　　　｝

＝＝3.7 16.1 × ×

21.616.1（）

1/1.28

32.5ℓ

13.4 ×｛｝－121.616.1（）

1/1.85

Polytropic Exponents at for discharge time

n 1.85

Polytropic Exponents at charge time m 1.28※Refer to the polytropic exponents in ②Ex.

Confirmation of maximum allowable discharge Flow （Qmax）

Qmax＝ ΔV×60Tn

3.7ℓ×601.5sec＝＝148ℓ/min

　　　　　From the above calculation, the required accumulator's function is that the accumulator gas volume （V1） is 32.5ℓ or more and the maximum allowable discharge flow is 148 ℓ/min.　 In the case, the recommended accumulator model is G/T230-30.

Please select the accumulator model from this catalogue in consideration of the maximum working pressure （P3）, the accumulator gas volume （V1） and the maximum allowable discharge flow （Qmax）

29

NAKAMURA KOKI CALCULATION FORM for pulsation dampingSystem Name・Use Place

Date:

◎Please use the absolute pressure in the calculation （Absolute pressure （MPaA） = Gauge pressure （MPaG） + 0.1 ）

Pump Type （　　　）cylinder [ Single acting・Double acting ]

F1 ： Pump Coefficient

Pump Type F1

SimplexSingle acting 0.60

Double acting 0.25

DuplexSingle acting 0.25

Double acting 0.15

TriplexSingle acting 0.13

Double acting 0.06

QuadruplexSingle acting 0.10

Double acting 0.06

QuintupleSingle acting 0.06

Double acting 0.02

Average Working Pressure Px MPaA Average pressure of the liquid

Max Allowable Pressure Pm MPaA Maximum pressure of the liquid


Pump Delivery Q ℓ/min -

Revolution of Pump N rpm -

Pump Delivery per Revolution q ℓ/rev q = Q （Pump delivery ） / N （Revolution of pump ）

Polytropic Exponent n ②

Pump Coefficient F1 From table shown on the right hand

Accumulator Gas Volume V1 ℓ ③

①Calculation for determining the precharge pressure value

※Please apply the value of a or b.a. P1 = 0.6× Px（Average working pressure）

b. When there is temperature change, the below formula is applied.

　　 273+Min temprature（℃）P1 ＝　　　　　　　　　　　 ×0.6×Px（Average working pressure）　　 273+Max temprature（℃）

②Polytropic Exponents Check the average working pressure （Px） and confirm the polytropic exponent from the graph shown in page 3.Please contact our sales office if you have any questions.

③Gas Volume Calculation Formula of the Accumulator

<Pulsation Damping>（　）（　）

V1＝＝q×F1× Px

P1

1－PxPm

1n

＝　　× ×（）

ℓ1－（）

1/

MPaA

MPaA

MPaA

MPaA

ℓ/min

　rpm


Calculation Example Assume that we control the pump pulsation within 3% of the average working pressure. By using the following calculation, we confirm the accumulator gas capacity. The detailed specification is shown in the below table.Pump type：Plunger Pump Simplex Single acting Accumulator gas volume （V1）

（　）（　）

V1＝＝q×F1× Px

P1

1－ PxPm

1n

＝× ×（）

26.8ℓ1－（）

1/1.51

5.13.1

3262

5.15.25

0.60

From the above calculation, the accumulator gas volume （V1） of 26.8ℓ or more is required to control the pressure within 3% of the average working pressure. （In the practical aspect, because the flow velocity and the length of the connecting pipe is involved, it becomes a target value.） In the case, the recommended accumulator model is G/T175-30.As to the effects of pulsation dampener, please refer the sample in page 7.

Average Working Pressure Px 5.1 MPaAMax Allowable Pressure Pm 5.25 MPaAPrecharge Pressure P1 3.1 MPaAPump Delivery Q 32 ℓ/minRevolution of Pump N 62 rpmPump Coefficient F1 0.60Polytropic Exponent n 1.51※ Polytropic exponent at the average working

pressure 5.1MPaA is determined from the table in page 3.

Please select the accumulator model from this catalogue in consideration of the maximum working pressure （Pm） and the accumulator gas volume （V1）.

30

NAKAMURA KOKI CALCULATION FORM for surge absorptionSystem Name・Use Place

Date:

◎Please use the absolute pressure in the calculation （Absolute pressure （MPaA） = Gauge pressure （MPaG） + 0.1 ）.

Normal Working Pressure PA MPaA Pressure in the pipe where the surge pressure has not been generated.

Max Allowable Pressure PB MPaA Maximum allowable surge pressure


Inside Diameter of Pipe d mm

Length of Pipe L m

Fluid Density ρ kg/m³ Petroleum-based hydraulic oil ≒900 kg/m³ Water≒1000 kg/m³ Phosphoric acid ester-based hydraulic oil

≒1100 kg/m³

Mass of Fluid in Line M kg ③

Flow Rate of Fluid Q ℓ/min

Flow Velocity ν m/sec ④

Polytropic Exponent n ②

Accumulator Gas Volume V1 ℓ ⑤

①Calculation for determining the precharge pressure value

※Please apply the value of a or b.a. P1 = 0.9×PA

b. When there is temperature change, the below formula is applied

　　 273+Min temprature（℃）P1 ＝　　　　　　　　　　　 ×0.9×PA　　 273+Max temprature（℃）

②Polytropic Exponent Check the normal working pressure （PA） and confirm the polytropic exponent from the graph shown in page 3.Please contact our sales office if you have any questions.

③Mass of Fluid in Line （M）Calculation formula M ＝　×ｄ2×L×ρ＝　×（ Inside diameter ×10－3 ）

2× Length × Fluid density ＝

π４

π４ kg

④Flow Velocity （ν） Calculation formula υ＝ 21.23 ×　　＝ 21.23 × 　　　　　　＝Q

d2 m/sec　　　　Flow rate

　　　　Inside Diameter 2

⑤Accumulator Gas VolumeCalculation Formula

<Surge Absorption>

V1 ＝M×v 2×（n－1）

2000×P1×｛　　　｝（　）PB

PA

n-1n －1

＝＝ ℓ2000× 　　　　 ×（）

□－1□｛｝－1MPaA

×（　　　－1）kg　　　　m/sec×2

MPaA

MPaA


Calculation Example Assume that we reduce the surge pressure caused by sudden close of the valve that installed at the end of a pipe.The detailed specification is shown in the below table.Condition Precedent: External diameter = 8 B×Sch 40 (JIS: 216.3 mm×Thickness 8.2 mm)Normal Working Pressure PA 0.85 MPaA Mass of Fluid in Line

π４

π４M＝　×ｄ2×L×ρ＝　×（199.9×10－3）

2×700×900＝19772 kgMax. Allowable Pressure PB 1.35 MPaA

Prechargie Pressure P1 0.75 MPaAInside Diameter of Pipe d 199.9 mm Flow Velocity

v ＝21.23× 　＝ 21.23 × 　　　＝ 2.4m/secQd2

4500199.92

Length of Pipe L 700 mFluid Density ρ 900 Kg/m3

Mass of Fluid in Line M 19772 kg Gas volume

V1＝M×v 2×（n－1）

2000×P1×｛　　　｝（　）PB

PA

n-1n －1

＝＝216ℓ2000×0.75×（）

1.407－11.407｛｝－1

1.350.85

19722×2.42×（1.407－1）

From the above calculation, the accumulator gas volume （V1） is 216ℓ or more is required.In the case, the recommended accumulator model is TL175-230".

Flow Rate Q 4500 ℓ/minFlow Velocity ν 2.4 m/secPolytropic Exponent n 1.407※ Polytropic exponent at the average working

pressure 1.1MPaA is determined from the table in page 3.

Please select the accumulator model from this catalogue in consideration of the maximum working pressure （PB） and the accumulator gas volume （V1）.

　Safety Precautions for Accumulators　The accumulator is a pressure vessel containing pressurized fluid in it. Read the operation manual and well understand its content before using the vessel.To prevent injury to persons or damage to the accumulator, observe the safety precautions below.

1. Selecting an accumulator　�！ CAUTION : Accumulators are pressure vessels which are controlled under laws and regulations according to their place of use, pressure,

and capacity. When selecting an accumulator, be aware of such regulations.　�！ CAUTION : Select an accumulator which is compatible with its usage conditions, such as operating pressure, amount of work oil to be

pressurized, operating temperature, type of fluid to be charged in the accumulator, environmental considerations, and applicable regulations. If a wrong accumulator were selected, it could not only fail to perform to expectations but also adversely affect interconnected machines.

2. Installing an accumulator　�！ WARNING＊: Do not attempt to weld any thing to or drill a hole in an accumulator. Such an act would jeopardize its safety and could cause

it to explode.　�！ CAUTION : Secure an accumulator to the frame or wall with a band or other suitable means. If such a support were neglected, vibration

(due to normal operation or earthquake) would excessively stress the accumulator, and could eventually loosen its fasteners.　�！ CAUTION : Do not subject an accumulator to external heat.　　　　　　　　Put up a heat shield around the accumulator if it is near a heat source or exposed to direct sunlight. If an accumulator were

heated from outside, the fluid inside could build up a dangerously high pressure.　�！ CAUTION : As a safety measure, provide a pressure control valve in the piping system at a location near and directly connected to the

accumulator so that its maximum allowable pressure will never be exceeded.

3. Charging an accumulator with nitrogen gas (precharging)　�！ WARNING＊: Only use nitrogen gas as the fluid precharged in an accumulator. Never use oxygen or flammable gas because it could

cause a fire or explosion.　�！ CAUTION : While no regulatory qualification is required (in Japan) for a person to charge an accumulator with nitrogen gas, it is

important for personal safety that the person be trained for handling high-pressure gases. When charging an accumulator with nitrogen gas, use a charging assembly which is compatible with the accumulator.

4. Using a charging assembly　�！ CAUTION : A charging assembly is used for precharging, replenishing, or pressure calibration. Attach a charging assembly to an

accumulator only before use, and always remove it from the accumulator after use. A charging assembly as permanently attached to an accumulator could increase the possibility of gas leak or damage to its instruments.

5. Using an accumulator　�！ WARNING : Ensure that an accumulator is used at pressures not exceeding its maximum working pressure (design pressure). Excessive

pressure could cause the accumulator to explode.　�！ CAUTION : Do not leave an accumulator charged only with pressurized fluid but not with work oil for more than two weeks. Otherwise,

the bladder rubber could permanently stick to the inside surface of the shell.

6. Maintaining an accumulator　�！ CAUTION : To ensure maximum performance of an accumulator and the integrity of its bladder, check and adjust an accumulator right

after precharging, one week after the precharging, and every three months thereafter. When measuring the pressure of the fluid in an accumulator, the pressure inside the work oil circuit must be equal to the pressure of the outside atmosphere.

7. Disassembling, reassembling, or discarding an accumulator　�！ WARNING＊: Reduce the pressure inside the work oil circuit to the pressure of the atmosphere and completely discharge the fluid from

the accumulator before attempting to disassemble it. If you attempted to disassemble it with some pressure inside, you could be injured by the pressure.

　�！ WARNING＊: Before discharging the fluid from an accumulator, ensure that the area is well ventilated. Otherwise, there could be a danger of oxygen deficiency. Also ensure that there is no person or objects that could be easily flown away in the direction in which the fluid is to be discharged. Otherwise, the high-pressure jet of the discharged fluid could injure a person or damage objects.

　�！ WARNING : After disassembling an accumulator, check and ensure that there is no significantly corroded, scratched, or deformed part in it before reassembling it. Any degraded part used undetected could endanger the safety of the accumulator.

　�！ CAUTION＊: If a T-series accumulator is disassembled and its bladder is removed off through the top portion, discharge away any fluid remaining at the bottom before replacing a new bladder. Otherwise, the new bladder could be deformed and damaged by the buoyancy from the remaining fluid.

　�！ CAUTION＊: When discarding an accumulator, first release both work oil and fluid pressures to the atmosphere, and then disassemble it and take necessary measures to make it unusable.

Note : The WARNING or CAUTION statements with the word WARNING or CAUTION indicated by the asterisk (＊) above are also marked on an accumulator in the form of a label.

�

Title:中村工機-P31.ec6 Page:19 Date: 2014/12/15 Mon 09:30:00

14.08A　1000

Ever since our company started to deliver bladder type accumulators in 1962, we do continuously achieve customer satisfaction by supplying the unique products in high quality and special technic.If you have any questions or if we can be of help in any way, please don't hesitate to let us know.We are looking forward to do business with you in near future!

〈PRODUCT LINE〉

Bladder type accumulatorsDiaphram type accumulatorsHydro-LungAccumulators with sensorsO-rings and special packings

Piston type accumulatorsAccumulator stop valveN2 gas boosters for charging gasIn-line type accumulators

(NOTE: There is a possibilly that the contents of this brochure is changed without notice.)

The factory is approved by CE, AQSIQ (China), METI (Japan), and certified by ASME (USA), ISO 9001 (Headquarter factory・accumulater)

Headquarter　　 18-43 Heizaemoncho, Amagasaki-shi, Hyogo-ken 660-0087, Japanfactory　　　　　Tel:81-6-6419-3791　　　　　　　　FAX:81-6-6419-3795　　　　　　　　E-Mail : [email protected]　　　　　　　　http : //www.hyd-acc.co.jpHead office:　　 18-43 Heizaemoncho, Amagasaki-shi, Hyogo-ken 660-0087, Japan　　　　　　　　Tel:81-6-6419-7600　　　　　　　　FAX:81-6-6419-3795　　　　　　　　E-Mail : [email protected] office :　　5-7-13-202 Shinbashi, Minato-ku, Tokyo 105-0004, Japan　　　　　　　　Tel:81-3-3435-1621　　　　　　　　FAX:81-3-3435-1624　　　　　　　　E-Mail : [email protected] office :5-28 Fukuro-machi, Naka-ku, Hiroshima-shi, Hiroshima-ken 730-0036,

Japan　　　　　　　　Tel:81-82-248-4093　　　　　　　　FAX:81-82-248-4096　　　　　　　　E-Mail : [email protected] in China :22-15-9 Sreet 22 HEAD Hangzhou, 310018 Zhejiang China.　　　　　　　　Tel:+86-571-2887-1126　　　　　　　　FAX:+86-571-2887-1125　　　　　　　　E-Mail : [email protected]

HANGZHOU NAKAMURA KOKI HYDRO TECHNICA CO., LTD.

Title:表4のみ.ec6 Page:1 Date: 2014/12/19 Fri 14:12:08

HYDRO PNEUMATIC ACCUMULATORS - … speaking, it is used to make pump/motor size small and also used...

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