Bladder Accummulators Inspections

7/31/2019 Bladder Accummulators Inspections

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Bladder AccumulatorsSB330/SB400/SB550

Operating andMaintenance Instructions

INDEX

1. DESCRIPTION

2. DELIVERYINSPECTION

3. INSTALLATION ANDMOUNTING

4. CONNECTION

5. COMMISSIONING ANDSAFETY

PRECAUTIONS

6. INSPECTION AND

MAINTENANCE

7. STORAGE ANDPRESERVATION

8. DISASSEMBLY,INSPECTION AND

ASSEMBLY

9. SPECIAL TOOLS AND

SPARE PARTS

10. CUSTOMER SERVICE


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6.2. CHARGING PROCEDUREWITH THE CHARGING ANDTESTING UNIT

Using the charging and testing unitFPU1, hydraulic accumulatorscan be charged with nitrogen tothe precharge pressure p0, ortested. Firstly, isolate the bladderaccumulator from the hydraulicsystem by closing the shutoffvalve A and discharge it on the

fluid side. Then remove the valveprotection cap, the cap nut and theOring. The charging and testingunit FPU1 and the nitrogen bottlecan now be connected inaccordance with the operatinginstructions (with adaptor A3).Ensure that the pressure releasevalve of the FPU1 is closed.Then slowly open the valve of thenitrogen bottle so that the nitrogenis released into the accumulator.Wait until approximately 1 bar hasbeen reached before opening theshutoff valve of the nitrogen

bottle further to enable fastercharging.Interrupt the charging procedurefrom time to time and check theprecharge pressure reached.When the required prechargepressure has been reached, closethe shutoff valve of the nitrogenbottle. Wait for approx. fiveminutes whilst temperatureequalisation takes place (a longerperiod must be allowed for largercharging quantities), thenrecheck the precharge pressureand adjust if necessary. If the

pressure is too high, it can belowered via the pressure releasevalve of the FPU1.Turn the spindle clockwise to closethe valve. Then discharge thecharging and testing unit via thepressure release valve andremove it by loosening the capnuts. Then check for leakages onthe accumulator gas valve using aleak detector spray. Screw on capnuts and valve protection cap(for torque ratings see Table 1,Point 8.5).Further details can be found in theHYDAC brochure HYDACCharging and Testing Unit and inthe operating instructions for theFPU1.

6.3. PRESSURE TESTING

For bladder accumulators with apermissible operating pressure pgreater than 1 bar and a pressurecapacity p*V > 1000, fornoncorrosive fluids, a pressuretest must be carried out by anapproval authority every 10 years,otherwise every 5 years.An internal inspection must becarried out every five years and an

external inspection every twoyears. For further information,refer to the (German) PressureVessels Regulations (DruckbehV).

7. STORAGE ANDPRESERVATIONIf the period of storage up untilcommissioning is no longer thanthree months, it is sufficient for theprecharged accumulator, which ismoistened on the inside withhydraulic fluid, to be stored in acool, dry place, protected fromdirect sunlight. The accumulatorcan be stored in any position. To

prevent contamination fromentering the accumulator, ensurethat the hydraulic connection isplugged.

If the accumulator is to be storedfor longer than three months,discharge the prechargepressure down to 2 bar to preventthe bladder from becomingdeformed.

When commissioning theaccumulator allow the hydraulicfluid to flow in slowly in order toprotect the bladder.

If the accumulator is intended tobe stored for longer than one yearit is advisable to disassemble itand store the accumulator andbladder separately. When storingaccumulator bladders, theDIN Standard 7716 RubberProducts, Guidelines for Storage,Maintenance and Cleaning mustbe followed.


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6.1. CHECKING THE NITROGEN PRESSURE WITHOUT ACHARGING AND TESTING UNIT

In this case, as shown in the following drawing, a pressure gauge isconnected to a line which is directly connected to the accumulator.

Isolate the fullycharged bladder accumulator from the hydraulicsystem by closing the shutoff valve A. Very slowly discharge theaccumulator on the fluid side via drain valve E. The pressure gaugemust be constantly monitored during this process. A slow, steadypressure drop is displayed. The pressure only drops abruptly when theaccumulator has been completely discharged. The pressure displayedbefore the drop corresponds to the precharge pressure of the bladderaccumulator. If this pressure lies below the permissible value, thecharging procedure must be carried out, as described in the followingsection.

E

W

A

6. INSPECTION AND

MAINTENANCEOn the whole, nitrogen losses onbladder accumulators are verylow. However, to prevent thebladder from becoming toodeformed if there is a drop in theprecharge pressure p0, a regularcheck of the precharge pressureis recommended. The precharge

pressure shown on the adhesivelabel or type code label must bereadjusted after every newinstallation or repair and thenchecked at least once during thefirst week. If no nitrogen loss isdetected, a further check shouldbe carried out after approximatelyfour months.

If after this period no pressurechange is detected, an annualcheck of the nitrogen pressure willbe sufficient.


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1. DESCRIPTIONThese Operating and MaintenanceInstructions apply to HYDACbladder accumulators of the seriesSB330 / SB400 / SB550

having the following specifications:permiss. operatingpressure: 330 / 400 / 550 barpermiss. operatingtemperature: 10 / +80 C

(standard, withNBR seal)

max.prechargepressure p0: p0,tmax 0.9 p1permiss.pressure ratiop2 : p0 4 : 1Design,Approval: TRB/AD

Regulations, TVwhere:p0 = precharge pressure,

p1= minimum operatingpressure,p2 = maximum operating pressureFor volumes, dimensions andweights (when empty), seedrawing or brochure.Manufacturer:HYDAC Technology GmbHGeschftsbereich SpeichertechnikPostfach 125166273 Sulzbach/SaarIndustriegebiet66280 Sulzbach/SaarGermany

Tel: 06897 / 50901Fax: 06897 / 509464

2. DELIVERYINSPECTIONPrior to delivery, HYDACaccumulators undergo a carefulinspection.

Upon receipt of the accumulator,check that:

no damage has been sustainedduring transport. In particular,carry out a visual check of the

gas valve and the hydraulicconnection for damage, the details shown on the type

code label correspond to theorder details

the test certificates (if required)are present and correspond tothe factory number of theaccumulator,

the protective cap of the gasvalve is tightly closed,

the hydraulic connection hasbeen closed off with aprotective plug.

3. INSTALLATION ANDMOUNTING

3.1. MOUNTING POSITION

The accumulators can be mountedboth vertically and horizontally.However, the vertical mountingposition with the gas valve at thetop is generally preferred.Irrespective of the mounting

position, the type code label orvessel label must be accessibleand legible.Sufficient clearance must be left tomount and disconnect the bladderaccumulator. In particular, an areaof at least 150 x 150 x 150 mmmust be left above the gas valvefor fitting and operating thecharging and testing unit FPU1.

3.2. MOUNTING

In accordance with therecommendations of the HYDACbrochure Supports for HydraulicAccumulators, HYDAC bladderaccumulators must be mountedvibrationfree using clamps andconsoles.NOTEMounting elements must neverbe welded to the bladderaccumulator.

On request we can build fullyassembled and connectedaccumulator stands as standardand special models.

4. CONNECTIONThe hydraulic connection onHYDAC bladder accumulators isthreaded as standard.The connection of the accumulatorto the pipe must be stressfreeand torquefree.It must be possible to isolate theaccumulator from the pressurisedhydraulic system. This means thatit must be possible to dischargethe vessel on the fluid side. In thisregard the (German) Pressure

Vessel Regulations (DruckbehV)and other relevant regulationsmust be observed.

5. COMMISSIONING ANDSAFETY PRECAUTIONSPrior to connecting theaccumulator to the pressurisedsystem, the precharge pressureshould be rechecked. If theaccumulator was precharged atHYDAC the pressure level can befound on the adhesive label orstamped on the type code label.

The level of the prechargepressure generally depends on thefollowing criteria: type of system, expected changes in operating

temperature,

intended function of theaccumulator.

5.1. COMMISSIONINGThe following prechargepressures are recommended:

for energy storage:p0,tmax = 0.9 p1for shock absorptionp0,tmax = 0.6 ... 0.9 pmpm= average operating pressure

for pulsation damping:p0,tmax = 0.6 ... 0.8 pm

Examples:

p0,tmax = 0.6 pmwith 1 piston pumpp0,tmax = 0.7 pmwith three or more piston pumpsp0,tmax = 0.8 pmwith operating pressure rangeCritical value of the gasprecharge pressure:

p0 0.9 p1

permiss. pressure ratio ofp2 : p0 4 : 1Further information on the gasprecharge pressures can befound in the HYDAC accumulatorbrochure Bladder Accumulatorsor Hydraulic Dampers.

Charging and testing of theprecharge pressure is describedin Point 6 Inspection andMaintenance.

5.2. VENTINGPrior to commissioning, theaccumulator must be vented via

the vent screw (Item 19). As soonas oil seeps past the vent screw,tighten it again. Then apply themaximum operating pressure tothe complete hydraulic system andcheck for leakages. Aftercommissioning, tighten the gasand oil valve lock nut (for torqueratings, see Point 8, Table 1).

5.3. SAFETY PRECAUTIONSNOTE!

Only use nitrogen to charge theaccumulator bladder, never

oxygen or compressed air(risk of explosion).If the pressure of the nitrogenbottle is higher than thepermissible operating pressure ofthe accumulator, a pressurerelease valve or gas pressurevalve must be fitted.


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8. DISASSEMBLY,INSPECTION ANDASSEMBLYSee Point 9.2 for item numbers

8.1. DISCONNECTION

Carefully clean the area aroundthe connections on the gas andfluid side.

On backup type bladderaccumulators the nitrogen feedline must be isolated by meansof the shutoff valve.

Completely release thepressure on the fluid side of theaccumulator.

Remove all nonpressurisedlines on the fluid side andremove the complete bladderaccumulator from the system.

8.2. DISASSEMBLY

Secure the accumulator to ahorizontal base and disassembleas follows:

The gas precharge pressuremust always be released first.

NOTE!When releasing nitrogen, ventilatearea well, danger of suffocation!

Unscrew valve protection cap

(item 6) and cap nut (item 5). Release the nitrogen pressure

using the charging and testingunit FPU1.

Remove gas valve insert(item 3) using a gas valvewrench.

Clamp small accumulators in avice and secure large ones onan assembly bench (clamps,chains etc.).

Remove vent screw (item 19).

Loosen and unscrew lock nut

(item 18) with a Cspanner. Remove spacer (item 17).

If not easily removable it can beknocked loose using a plastichammer.

Loosen valve and slide it intothe body.

Reach into the opening andremove the Oring (item 16)and the washer (item 15) fromthe oil valve (if fitted, thesupport ring (item 23) shouldalso be removed).

Strip antiextrusion ring(item 14) from the oil valve, foldand remove it.

Remove oil valve.

Loosen lock nut (item 4) on thegas valve and remove bladder.

NOTE!Collect hydraulic fluid drainingfrom the gas and fluid side in asuitable container!

8.3. INSPECTION OFCOMPONENTS

a) Pressure vessel

Carefully clean the inside of thepressure vessel with anonaggressive, nonabrasivecleaning agent, then dry with alintfree cloth.

Check that the bore on the fluidside is undamaged to ensure thatthe Oring provides a tight seal.

If any external or internal damageis found, the pressure vessel mustbe submitted immediately to themanufacturer and, if applicable,the appropriate inspectionauthority for assessment.

b) BladderCharge the bladder fully withnitrogen, or possibly compressedair, and check for damage. Thebladder must be replaced if thereis evidence of even the slightestleak. Revulcanisation or repair isneither possible nor permissible.

Possible chafe marks should beexamined for depth. If such chafemarks exist, it is advisable tocheck the pressure vessel againfor rough spots. Small grooves inthe elastomer are not significantand do not impair the function ofthe bladder. If the gas valve insertis leaking, it must be replaced witha new one. The seat can beslightly abraded beforehand usinga special tool. Even bladdersunder more operating pressure (inthe pressure vessel) must beabsolutely leakfree at the gas

valve. If this is not the case, thebladder must be replaced.

c) Oil valvePush down valve plate and turnthrough approximately ninetydegrees a few times to ensure thatit moves freely. The valve plateshaft must be free of grooves andthe selflocking nut must be tight.The valve plate, fitting surfacesand threads must be undamaged.If a new selflocking nut is to befitted, it must be secured withadhesive. There must be no

damage due to the effect of force.d) Antiextrusion ringThe ring must be replaced if theelastomer is badly cracked orshows signs of embrittlement orageing. (There must be nogrooves or rough areas on theseat surfaces).

e) Seal kit

The seals should always bereplaced.

f) Other partsThese should also be checked fordamage and replaced where

necessary.


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8.4. ASSEMBLY

Assembly is carried out as follows: Moisten the inside of the

accumulator with the operatingmedium.

Unscrew protective cap(item 6), cap nut (item 5) andlock nut (item 4).

Remove gas valve insert(item 3) using gas valve

wrench. Press the bladder to expel all

the air. Larger bladders can berolled up to the gas valve.Spray the bladder with oil or theintended operating medium.

IMPORTANT!

Do not use pure water as wateralone does not constitute apermanent lubricant.Exception: accumulators that arespecially designed for use withpure water. Large bladders should be

screwed onto a pull rod at theexternal thread of the valveVg 8 and inserted carefully.

NOTE!

Do not twist bladder wheninserting it! Screw lock nut (item 4) loosely

onto the gas valve.

Inflate the bladder with air until ittouches the side of theaccumulator.

Insert oil valve into the body.Make sure that the bladder has

not folded over.

Fold antiextrusion ring(item 14) slightly and insert itinto the body.Push antiextrusion ring ontothe oil valve.

Assembly order:

Washer Item 15Oring Item 16Support ring Item 23Spacer Item 17Lock nut Item 18

Firstly, push the Oring intoposition at four different points.A blunt, rounded screwdrivercan be used for this purpose.To protect the Oring, the oilvalve thread can be coveredwith adhesive tape.

Insert the spacer and screw onthe lock nut; tighten up lock nutwith a Cspanner.

Screw in vent screw (item 19)with seal ring (item 20).

Remove loosely screwedon

lock nut (item 4), position typecode label and tighten securelywith lock nut.

Screw in gas valve insert usinga torque wrench.

Apply precharge pressure, asdescribed in Point 6.2.

Since the precharge pressurechanges proportionally to the gastemperature, approximately 5minutes waiting time must beallowed, or in the case of largequantities of nitrogen and highpressures, up to approximately 1hour, after the requiredaccumulator precharge pressurehas been reached, to allow thetemperature to equalise. Thencheck the precharge pressureagain and adjust if necessary. Screw on the cap nut and the

valve protection cap (usetorque ratings given in Table 1,Point 8.5)

Tighten retaining nut (item 4),(use torque ratings given inTable 1, Point 8.5)

8.5. TORQUE RATINGS

Designation Item SB 330/400 SB 550 SB 330/400 H

0.5 1 l 2.5 5 l 10 50 l 1 5 l 10 50 l

[ Nm ]

Lock nut 18 90 200 440 150 600

Vent screw 19 3 3 30 3 30

Safety nut 12 4 12 25 12 45

Gas valve insert 3 0.3 0.5

Lock nut with

7/8 14 UNF 4 80

M 50 x 1.5 150

Cap nut 5 30

Table 1: Torque ratings


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9. Special tools and spare parts

9.1. SPECIAL TOOLS

Designation ItemGas valve insert 3

Repair kit consisting of:Bladder 2Gas valve insert 3Lock nut 4Cap nut 5

Valve protection cap 6Oring 7Washer 15Oring 16Seal ring 20Support ring 23Oring 27Antiextrusion ring 14

Oil valve, complete, consisting of:Oil valve body 9Valve plate 10Damping sleeve 11Safety nut 12Valve spring 13Antiextrusion ring 14Washer 15Oring 16Spacer 17Lock nut 18Vent screw 19Seal ring 20Support ring 23

Seal kit consisting ofOring 7Washer 15Oring 16Seal ring 20

Support ring 23Oring 27

9.2. SPARE PARTS

10. CUSTOMER SERVICECustomer service, in particular repairs and pressurerepeat tests, can be carried out at our head office:

HYDAC Technology GmbHGeschftsbereich Zentraler Kundendienst

Postfach 125166273 Sulzbach/Saar

Industriegebiet66280 Sulzbach/SaarGermanyTel: 06897 / 50901Fax: 06897 / 509828

or at any national or international HYDAC Sales andService branch.

Detail X

SB330/4000.56l

Detail XSB330/400 (H)10650l

SB55015lSB6001050l

In addition to the commercially available screwdrivers and torque wrenches, the following tools, which can bepurchased from Hydac, are required.

Tool HYDAC Stock no.

Gas valve wrench 616886

Torque wrench 379354

Cspanner Specialist suppliers

Table 2: Special tools

Bladder Accummulators Inspections

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