HYDAC SK 600 User Manual

Accumulators

SK 210 / 350 / 600

Piston Accumulators

Maintenance and Parts

Index

1. Description

2. Deliver y Inspection

3. Installation and Mounting

4. Connection

5. Commissioning and Precautions

6. Inspection and Maintenance

7. Storage and Preservation

8. Disassembly, Inspection and Assembly

9. Special Tools and Spare Parts

1. Description

These Operating and Maintenance Instructions apply to HYDAC piston accumulators of the series SK210, SK350 and SK 600 having the following speciﬁcations:

permiss. operating pressure: 210 / 350 bar

permiss. operating temperature: –10 / 80°C with NBR seal

max. pre–charge pressure p0: p

permiss. pressure ratio p0: p2 ≤ 1 : ∞

Design, Approval: PED/AD–Regulations, ASME

For volumes, dimensions and weights (when empty), see drawing or brochure.

≤ p1 – 5 bar

0,tmax

2. Delivery Inspection

Prior to delivery, HYDAC accumulators undergo a careful inspection. Upon receipt of the accumulator, check that:

• no damage has been sustained during transport. In particular,

check the gas valve and the hydraulic connection for damage,

• the details shown on the model code correspond to the order

details,

• the test certiﬁcates (if required) are present and correspond

to the factory number of the accumulator,

• the protective cap of the gas valve is tightly closed,

• the hydraulic connection has been closed off with a

protective plug.

After discharging and/or completely draining the accumulator (e.g. to depressurize the hydraulic system before work is carried out), the accumulator can build-up an amount of pressure again when

CAUTION!

PN#02068195 / 04.13 / ACU1102-1326

the lines are later shut off on the ﬂuid side.

This problem must be taken into account generally and in particular before carrying out work on hydraulic systems which include connected hydraulic accumulators.

All the ﬂuid-side lines connected to the accumulator must therefore be depressurized and after that the lines remain open. Only then may the appropriate work (e.g. disassembly of the accumulator) be carried out.

PRESSURIZED VESSEL USE DRY

NITROGEN GAS ONLY

Please refer to HYDAC Operating

and Installation Instructions

CAUTION!

INNOVATIVE FLUID POWER

Maintenance

3. Installation and Mounting

3.1. Mounting Position

The piston accumulators can be mounted in any position. However, the vertical mounting position with the gas valve at the top is generally preferred.

Sufﬁcient clearance must be left to mount and disconnect the piston accumulator. In particular, an area of at least 150 x 150 x 150 mm must be left above the gas valve for ﬁtting and operating the charging and gauging unit.

3.2. Mounting

In accordance with the recommendations of the HYDAC brochure “Mounting Components”, HYDAC piston accumulators must be mounted vibration free using clamps and base brackets.

Note: Mounting elements must never be welded to the

piston accumulator.

4. Connection

The connection of the accumulator to the system must be stress free and torque free.

It must be possible to isolate the accumulator from the pressurized hydraulic system.

5. Commissioning and Safety Precautions

5.2. Venting

Prior to commissioning, the accumulator must be vented on the oil side. Then apply the maximum operating pressure to the complete hydraulic system and check for leakages.

5.3. Safety Precautions

IMPORTANT!

Only use nitrogen to charge the accumulator, never oxygen or compressed air (risk of explosion).

If the pressure of the nitrogen bottle is higher than the permissible operating pressure of the accumulator, a pressure regulating valve must be ﬁtted.

6. Inspection and Maintenance

On the whole, nitrogen losses on piston accumulators are very low. However, it is advisable to check the precharge pressure p0 at least once during the ﬁrst week following commissioning so that larger nitrogen losses can be detected immediately. During the course of the ﬁrst two months check the precharge pressure every two weeks, and thereafter every four weeks. If af ter this period no pressure change is detected, an annual check of the nitrogen pressure is sufﬁcient.

6.1. Checking the Nitrogen Pressure without a Charging and Gauging Unit

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

5.1 Commissioning

Prior to connecting the accumulator to the pressurized system, the precharge pressure should be rechecked. If the accumulator was precharged at HYDAC the pressure level can be found on the label.

The level of the precharge pressure generally depends on the following criteria:

• type of system,

• expected changes in operating temperature,

• intended function of the accumulator.

The following precharge pressures are recommended:

for energy storage:

≤ P1 - 5 bar

0,tmax

≥ 2 bar

0,tmin

for volume compensation:

p0 = static pressure of the system

Further information on the gas precharge pressures can be found in the HYDAC accumulator brochure “Piston Accumulators”. Charging and gauging of the precharge pressure is described in Point 6 “Inspection and Maintenance”.

Isolate the fully charged piston accumulator from the hydraulic system by closing the shut off valve A. Slowly discharge the accumulator on the ﬂuid side via drain valve E. The pressure gauge must be constantly monitored during this process. A slow, steady pressure drop is displayed. The pressure only drops abruptly when the accumulator has been completely discharged. The pressure displayed before the drop corresponds to the precharge pressure of the piston accumulator. If this pressure lies below the permissible value, the charging procedure must be carried out, as described in the following section.

INNOVATIVE FLUID POWER

PN#02068195 / 04.13 / ACU1102-1326

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