BUSCH COBRA User manual

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COBRA
Dry Screw Vacuum Pumps
NC 2500 B Water-Cooled Version (WCV)
Instruction Manual
0870558967 | A0008_en-US | Original instructions 11/30/2022

Table of Contents
2 | 52 Instruction Manual COBRA NC 2500 B WCV_EN_en
Table of Contents
1 Safety..................................................................................................................................................................... 4
2 Product Description............................................................................................................................................. 5
2.1 Operating Principle ............................................................................................................................................. 6
2.2 Intended Use ....................................................................................................................................................... 6
2.3 Start Controls....................................................................................................................................................... 7
2.4 Standard Features............................................................................................................................................... 7
2.4.1 Water Cooling........................................................................................................................................ 7
2.4.2 Cooling Gas Unit ................................................................................................................................... 7
2.4.3 Resistance Thermometer (Cooling Liquid) ........................................................................................ 7
2.4.4 Resistance Thermometer (Exhaust Gas) ............................................................................................ 7
2.4.5 Sealing Systems..................................................................................................................................... 7
2.5 Optional Accessories........................................................................................................................................... 7
2.5.1 Silencer................................................................................................................................................... 7
2.5.2 Vibration Diagnostic Unit..................................................................................................................... 7
2.5.3 Mechanical Seals................................................................................................................................... 8
3 Transport .............................................................................................................................................................. 9
4 Storage .................................................................................................................................................................. 11
5 Installation ........................................................................................................................................................... 12
5.1 Installation Conditions........................................................................................................................................ 12
5.2 Connecting Lines / Pipes .................................................................................................................................... 12
5.2.1 Suction Connection............................................................................................................................... 13
5.2.2 Discharge Connection .......................................................................................................................... 13
5.2.3 Cooling Water Connection................................................................................................................... 14
5.2.4 Barrier Gas System Connection .......................................................................................................... 15
5.3 Filling Oil............................................................................................................................................................... 16
5.4 Filling Cooling Liquid........................................................................................................................................... 18
5.5 Fitting the Coupling ............................................................................................................................................ 19
6 Electrical Connection........................................................................................................................................... 20
6.1 Machine delivered without Variable Speed Drive ........................................................................................... 20
6.2 Wiring Diagram Three-Phase Motor (Pump Drive)......................................................................................... 21
6.3 Electrical Connection of the Cooling Liquid Pump.......................................................................................... 22
6.3.1 Wiring Diagram Cooling Liquid Pump................................................................................................ 23
6.4 Electrical Connection of the Monitoring Devices ............................................................................................ 24
6.4.1 Wiring Diagram Resistance Thermometer ........................................................................................ 24
6.4.2 Wiring Diagram Vibration Diagnostic Unit ........................................................................................ 24
7 Commissioning..................................................................................................................................................... 26
7.1 Recommendations on Operation...................................................................................................................... 27
7.1.1 Operating Frequency............................................................................................................................ 27
7.1.2 Stop & Start............................................................................................................................................ 27
7.1.3 Use with Argon...................................................................................................................................... 27
7.2 Conveying Condensable Vapors........................................................................................................................ 27
8 Maintenance......................................................................................................................................................... 28
8.1 Maintenance Schedule ....................................................................................................................................... 29
8.2 Oil Level Inspection............................................................................................................................................. 30
8.3 Cooling Liquid Level Inspection......................................................................................................................... 30
8.4 Oil Change............................................................................................................................................................ 31
8.5 Cooling Liquid Change ....................................................................................................................................... 34
8.6 Calibration Procedure of the Electrical Devices .............................................................................................. 38

Table of Contents
Instruction Manual COBRA NC 2500 B WCV_EN_en 3 | 52
8.6.1 Resistance Thermometer Calibration................................................................................................. 38
8.6.2 Vibration Sensor Calibration................................................................................................................ 38
9 Overhaul................................................................................................................................................................ 39
10 Decommissioning................................................................................................................................................. 40
10.1 Dismantling and Disposal .................................................................................................................................. 40
11 Spare Parts............................................................................................................................................................ 41
12 Troubleshooting................................................................................................................................................... 42
13 Technical Data...................................................................................................................................................... 44
14 Cooling Liquid....................................................................................................................................................... 45
15 Oil........................................................................................................................................................................... 46
16 EU Declaration of Conformity............................................................................................................................. 47
17 UK Declaration of Conformity ............................................................................................................................ 48

1 | Safety
4 | 52 Instruction Manual COBRA NC 2500 B WCV_EN_en
1 Safety
Prior to handling the machine, this instruction manual should be read and understood. If anything
needs to be clarified, please contact your Busch representative.
Read this manual carefully before use and keep for future reference.
This instruction manual remains valid as long as the customer does not change anything on the
product.
The machine is intended for industrial use. It must be handled only by technically trained personnel.
Always wear appropriate personal protective equipment in accordance with the local regulations.
The machine has been designed and manufactured according to state-of-the-art methods. Never-
theless, residual risks may remain, as described in the following chapters and in accordance with the
chapter Intended Use [➔6]. This instruction manual highlights potential hazards where appropri-
ate. Safety notes and warning messages are tagged with one of the keywords DANGER, WARNING,
CAUTION, NOTICE and NOTE as follows:
DANGER
... indicates an imminent dangerous situation that will result in death or serious injuries if not
prevented.
WARNING
... indicates a potentially dangerous situation that could result in death or serious injuries.
CAUTION
... indicates a potentially dangerous situation that could result in minor injuries.
NOTICE
... indicates a potentially dangerous situation that could result in damage to property.
NOTE
... indicates helpful tips and recommendations, as well as information for efficient and trou-
ble-free operation.

Product Description | 2
Instruction Manual COBRA NC 2500 B WCV_EN_en 5 | 52
2 Product Description
CLV2
MP OSGODV
TSA2
OFP
CWIPHE CLPCWOCLD
INCLG
MTB
CLV1
CLF
OUT
EB EBCGU
MP OFP
OSG
OUTSI
ODV
CD
TSA1
SANP
TMBGS
ECP
TV
MP
Description
IN Suction connection (Inlet) with mesh screen OUT Discharge connection (Outlet)
BGS Barrier gas system CD Condensate drain
CGU Cooling gas unit (air filter included) CLD Cooling liquid drain plug*
CLF Cooling liquid fill plug CLG Cooling liquid sight glass
CLP Cooling liquid pump CLV1 Cooling liquid vent plug (cooling liquid
pump)
CLV2 Cooling liquid vent plug (machine) CWI Cooling water inlet
CWO Cooling water outlet EB Eye bolt
ECP Earth connection MP Magnetic plug
MTB Motor terminal box NP Nameplate
ODV Oil drain valve OFP Oil fill plug
OSG Oil sight glass PHE Plate heat exchanger
SA Vibration transmitter (option) SI Silencer (option)
TM Thermometer TSA1 Resistance thermometer (cooling liquid tem-
perature)
TSA2 Resistance thermometer (exhaust gas tem-
perature)
TV Thermostatic valve
*For additional cooling liquid drain plugs (CLD), see Cooling Liquid Change [➔34].

2 | Product Description
6 | 52 Instruction Manual COBRA NC 2500 B WCV_EN_en
NOTE
Technical term.
In this instruction manual, we consider that the term ‘machine’ refers to the ‘vacuum pump’.
NOTE
Illustrations
In this instruction manual, the illustrations may differ from the machine appearance.
2.1 Operating Principle
The machine works on the one-stage, twin-screw pump principle.
Two screw rotors rotate inside the cylinder. The pumped medium is trapped between the cylinder
and screw chambers, compressed, and transported to the gas outlet. During the compression pro-
cess, the two screw rotors do not come into contact with each other or with the cylinder. There is no
need for a lubrication or an operating fluid in the compression chamber.
2.2 Intended Use
WARNING
In case of foreseeable misuse outside the intended use of the machine.
Risk of injuries!
Risk of damages to the machine!
Risk of damages to the environment!
●Make sure to follow all instructions described in this manual.
The machine is intended for the suction of air and other dry, non-aggressive, non-toxic and non-ex-
plosive gases.
Conveying of other media leads to an increased thermal and/or mechanical load on the machine
and is permissible only after a consultation with Busch.
The machine is intended for the placement in a non-potentially explosive environment.
The machine is capable of maintaining ultimate pressure, see Technical Data.
The machine is suitable for continuous operation.
Permitted environmental conditions, see Technical Data.

Product Description | 2
Instruction Manual COBRA NC 2500 B WCV_EN_en 7 | 52
2.3 Start Controls
The machine comes without start controls. The control of the machine is to be provided in the
course of installation.
The machine must be equipped with a variable speed drive (not included in the scope of supply).
2.4 Standard Features
2.4.1 Water Cooling
The machine is cooled by a cooling liquid circuit in the cylinder cover and cylinder.
The cooling liquid pump (CLP) allows a recirculating flow in the cooling liquid chamber.
The motor of the cooling liquid pump must be electrically connected, see Electrical Connection of the
Cooling Liquid Pump [➔22]
The cooling liquid is cooled by a plate heat exchanger (PHE) which must be connected to the water
main.
2.4.2 Cooling Gas Unit
The purpose of the cooling gas unit (CGU), including an air filter is to cool the compression chamber
and reduce the amount of heat generated by the compression of the process gases.
By inlet pressure < 300 mbar, cooling air is automatically drawn in through an air filter.
2.4.3 Resistance Thermometer (Cooling Liquid)
The resistance thermometer monitors the cooling liquid temperature of the machine.
Warning and trip signals must be set, see Wiring Diagram Resistance Thermometer [➔24].
2.4.4 Resistance Thermometer (Exhaust Gas)
The resistance thermometer monitors the exhaust gas temperature at the machine discharge.
Warning and trip signals must be set, see Wiring Diagram Resistance Thermometer [➔24].
2.4.5 Sealing Systems
The machine is equipped with labyrinth seals on the motor side and suction side.
Other sealing systems are optionally available, see Mechanical Seals [➔8].
Sealing systems prevent the process gas going to the bearings chambers.
The sealing systems include a barrier gas system, see Barrier Gas System Connection [➔15].
2.5 Optional Accessories
2.5.1 Silencer
A silencer at the discharge connection (OUT) can be provided to reduce the exhaust gas noise.
2.5.2 Vibration Diagnostic Unit
The vibration diagnostic unit monitors the correct mechanical operation of the machine.
This unit is composed of a vibration sensor (SA) and a diagnostic electronics VSE100 (delivered
loose).
The machine must be stopped when the vibration limit value (preset at the factory) is reached, see
Wiring Diagram Vibration Diagnostic Unit [➔24].

2 | Product Description
8 | 52 Instruction Manual COBRA NC 2500 B WCV_EN_en
2.5.3 Mechanical Seals
The sealing systems can be equipped with mechanical seals. The following variants are possible:
●Oil lubricated single mechanical seals on the motor side and labyrinth seals on the suction side.
●Oil lubricated single mechanical seals on the motor side and suction side.

Transport | 3
Instruction Manual COBRA NC 2500 B WCV_EN_en 9 | 52
3 Transport
WARNING
Suspended load.
Risk of severe injury!
●Do not walk, stand or work under suspended loads.
WARNING
Lifting the machine using the motor eye bolt.
Risk of severe injury!
●Do not lift the machine using the eye bolt fitted to the motor. Only lift the machine as shown.
NOTICE
In case the machine is already filled with oil.
Tilting a machine that is already filled with oil can cause large quantities of oil to ingress into
the cylinder.
●Drain the oil prior to every transport or always horizontally transport the machine.
●To find out the weight of the machine, refer to the chapter Technical Data or the nameplate (NP).
●Make sure that the eye bolt(s) (EB) is/are in faultless condition, fully screwed in and tightened by
hand.
Transport with a lifting hook
1
23
Description
1 The air filter must be removed before
lifting the machine!
2 l1 = ~430 mm
3 l2 & l3 = ~650 mm

3 | Transport
10 | 52 Instruction Manual COBRA NC 2500 B WCV_EN_en
Transport with a forklift
1
Description
1 Handling access must be from the un-
derneath of the base frame
●Check the machine for transport damage.
If the machine is secured to a base plate:
●Remove the machine from the base plate.

Storage | 4
Instruction Manual COBRA NC 2500 B WCV_EN_en 11 | 52
4 Storage
●Seal all apertures with adhesive tape or reuse provided caps.
If the machine is to be stored for more than 3 months:
●Wrap the machine in a corrosion inhibiting film.
●Store the machine indoors, dry, dust free and if possible in original packaging preferably at
temperatures between 5 ... 55 °C.
NOTICE
Long storage time.
Risk of damage to the machine!
●If the machine is equipped with oil lubricated mechanical seals, we recommend to completely fill
the oil chamber before a long storage, see “Oil filling” in chapter Oil Change [➔31]. This protects
the mechanical seals during a long storage. Use the standard pump oil, see chapter Oil [➔46].
●Before restarting the machine, drain the oil to the normal oil level, see “Oil draining” in chapter Oil
Change [➔31].

5 | Installation
12 | 52 Instruction Manual COBRA NC 2500 B WCV_EN_en
5 Installation
5.1 Installation Conditions
WARNING
If the machine is installed in a potentially explosive environment or if the machine is used to
draw toxic, inflammable or non-inert gases:
Risk of injuries!
Risk of death!
●Ensure that the machine complies with all local, national rules and safety regulations.
NOTICE
Use of the machine outside of the permitted installation conditions.
Risk of premature failure!
Loss of efficiency!
●Take care that the installation conditions are fully complied with.
●Make sure that the environment of the machine is not potentially explosive.
●Make sure that the ambient conditions comply with the Technical Data.
●Make sure that the environmental conditions comply with the protection class of the motor and
the electrical elements.
●Make sure that the installation space or location is vented such that sufficient cooling of the ma-
chine is provided.
●Make sure that cooling air inlets and outlets of the motor fan are not covered or obstructed and
that the cooling air flow is not affected adversely in any other way.
●Make sure that the oil sight glass (OSG) remains easily visible.
●Make sure that enough space remains for maintenance work.
●Make sure that the machine is placed or mounted horizontally, a maximum deviation of 1° in any
direction is acceptable.
●Check the oil level, see Oil Level Inspection [➔30].
●Check the cooling liquid level, see Cooling Liquid Level Inspection [➔30].
If the machine is installed at an altitude greater than 1000 meters above sea level:
●Contact your Busch representative, the motor should be derated or the ambient temperature
limited.
5.2 Connecting Lines / Pipes
WARNING
Rotating Parts.
Risk of severe injury!
●Do not operate the machine without suction / discharge connection installed.

Installation | 5
Instruction Manual COBRA NC 2500 B WCV_EN_en 13 | 52
●Remove all protective covers before installation.
●Make sure that the connection lines cause no stress on the connection of the machine; if neces-
sary use flexible joints.
●Make sure that the line size of the connection lines over the entire length is at least as large as
the connections of the machine.
In case of long connection lines, it is advisable to use larger line sizes in order to avoid a loss of effi-
ciency. Seek advice from your Busch representative.
5.2.1 Suction Connection
WARNING
Unprotected suction connection.
Risk of severe injury!
●Do not put hand or fingers in the suction connection.
NOTICE
Ingress of foreign objects or liquids.
Risk of damage to the machine!
If the inlet gas contains dust or other foreign solid particles:
●Install a suitable filter (5micron or less) upstream from the machine.
Connection size(s):
– DN150 PN16, EN 1092-1
– ANSI 150, 6”
If the machine is used as part of a vacuum system:
●Busch recommends the installation of an isolation valve in order to prevent the machine from
turning backwards.
5.2.2 Discharge Connection
NOTICE
Discharge gas flow obstructed.
Risk of damage to the machine!
●Make sure that the discharged gas will flow without obstruction. Do not shut off or throttle the
discharge line or use it as a pressurized air source.
Connection size(s):
At the machine discharge connection:
– DN100 PN16, EN 1092-1
– ANSI 150, 4”
At the silencer (SI) discharge connection:
– DN100 ISO-K, DIN 28404
●Make sure that the counter pressure (also termed back pressure) at the discharge connection
(OUT) does not exceed the maximum allowable discharge pressure, see Technical Data.

5 | Installation
14 | 52 Instruction Manual COBRA NC 2500 B WCV_EN_en
5.2.3 Cooling Water Connection
CWO CWIPHE
Description
CWI Cooling water inlet CWO Cooling water outlet
PHE Plate heat exchanger
●Connect the cooling water connections (CWI / CWO) to the water supply.
Connection size:
– G1/2, ISO 228-1 (CWI / CWO)
●Make sure that the cooling water complies with the following requirements:
Supply capacity l/min 18
Water pressure bar 1 ... 6
Supply temperature °C +10 ... +30
Required pressure differential across supply
and return
bar ≥ 1
●To reduce the maintenance effort and ensure a long product lifetime we recommend the follow-
ing cooling water quality:
Hardness mg/l (ppm) < 90
Properties Clean & clear
PH value 7 ... 8
Particle size µm < 200
Chloride mg/l < 100
Electrical conductivity µS/cm ≤ 100
Free chloride mg/l < 0.3
Materials in contact with the cooling water Stainless steel

Installation | 5
Instruction Manual COBRA NC 2500 B WCV_EN_en 15 | 52
NOTE
Water hardness unit conversion.
1 mg/l (ppm) = 0.056 °dh (german degree) = 0.07 °e (english degree) = 0.1 °fH (french degree)
5.2.4 Barrier Gas System Connection
Without nitrogen panel
PRV FRBGC MAN FME
Description
BGC Barrier gas connection FME Flow meter
FR Flow regulator MAN Manometer
PRV Pressure regulating valve
●Connect the barrier gas connection (BGC) to the gas supply.
Connection size:
– G1/4, ISO 228-1
●Make sure that the gas complies with the following requirements:
Gas type Dry nitrogen or air
Gas temperature °C 0 ... 60
Maximum gas pressure bar 13
Recommended pressure setting at the pres-
sure regulating valve (PRV)
bar(a) 3
Filtration µm 5
Recommended flow rate SLM (standard li-
ter per minute)
30
Air quality (only for air) Acc. to ISO
8573-1
Class 5.4.4.

5 | Installation
16 | 52 Instruction Manual COBRA NC 2500 B WCV_EN_en
5.3 Filling Oil
NOTICE
Use of an inappropriate oil.
Risk of premature failure!
Loss of efficiency!
●Only use an oil type which has previously been approved and recommended by Busch.
For oil type and oil capacity see Technical Data and Oil [➔46].

Installation | 5
Instruction Manual COBRA NC 2500 B WCV_EN_en 17 | 52
When the oil filling is achieved:
●Write down the oil change date on the sticker.
Last oil change
__ / __ / ____
Oil type see nameplate
Change interval see
instruction manual
If there is no sticker (part no. 0565 568 959) on the machine:
●Order it from your Busch representative.

5 | Installation
18 | 52 Instruction Manual COBRA NC 2500 B WCV_EN_en
5.4 Filling Cooling Liquid
For cooling liquid type and cooling liquid capacity see Technical Data and Cooling Liquid [➔45].
1
2
Description
1 Cooling liquid vent plug (CLV1) 2 Fill up to the top of the vent orifice
(CLV1)
1
Description
1 Resume cooling liquid filling

Installation | 5
Instruction Manual COBRA NC 2500 B WCV_EN_en 19 | 52
5.5 Fitting the Coupling
NOTE
Radial screw.
For trouble-free operation, use thread locking glue to secure the radial screw.
1
2
3 4
5
Description
1 Coupling hub (machine side) 2 Coupling hub (motor side)
3 Elastic insert 4 Ring
5 Radial screw / max. admissible torque:
10Nm
Machine type Coupling size Value “E” (mm)
NC 2500 B Samiflex® A45 3,5 (0/+1)
In case of a machine delivery without motor:
●Fit the second coupling hub on the motor shaft (separately delivered).
●Axially adjust the hub in such a way until value "E" is reached.
●When the coupling adjustment is done, lock the coupling hub by tightening the radial screw.
For further coupling information, go to www.samiflex.se and download the instruction manual of the
Samiflex® coupling.

6 | Electrical Connection
20 | 52 Instruction Manual COBRA NC 2500 B WCV_EN_en
6 Electrical Connection
DANGER
Live wires.
Risk of electrical shock.
●Electrical installation work must only be executed by qualified personnel.
CURRENT PROTECTION OF THE CUSTOMER INSTALLATION:
DANGER
Missing current protection.
Risk of electrical shock.
●Current protection according to EN 60204-1 must be insured by the customer on its installation.
●The electrical installation must comply with the applicable national and international standards.
NOTICE
Electromagnetic compatibility.
●Make sure that the motor of the machine will not be affected by electric or electromagnetic dis-
turbance from the mains, if necessary seek advice from Busch.
●Make sure that the EMC of the machine is compliant with the requirements of your supply net-
work system, if necessary provide further interference suppression (EMC of the machine, see EU
Declaration of Conformity [➔47] or UK Declaration of Conformity [➔48]).
NOTE
●Make sure that the machine is started by a variable speed drive!
6.1 Machine delivered without Variable Speed Drive
DANGER
Live wires.
Risk of electrical shock.
●Electrical installation work must only be executed by qualified personnel.
●Make sure that the power supply for the motor is compatible with the data on the nameplate of
the motor.
●If the machine is equipped with a power connector, install a residual current protective device to
protect persons in case of isolation default.
●Busch recommends installing a type B residual protective device suitable for the electrical in-
stallation.