BUSCH COBRA ATEX NC 2500 B User manual

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Instruction Manual
COBRA
Dry Screw Vacuum Pumps
NC 2500 B (Water-Cooled Version)
0870558967/A0006_en / Original instructions / Modifications reserved 14/09/2021

Table of Contents
2 / 44 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 Application....................................................................................................................... 6
2.3 Start Controls .................................................................................................................. 6
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 ...................................................................................................... 8
2.5.1 Silencer ................................................................................................................ 8
2.5.2 Vibration Diagnostic Unit ...................................................................................... 8
2.5.3 Mechanical Seals ................................................................................................. 8
3 Transport ................................................................................................................................9
4 Storage....................................................................................................................................10
5 Installation ..............................................................................................................................11
5.1 Installation Conditions ..................................................................................................... 11
5.2 Connecting Lines / Pipes ................................................................................................ 11
5.2.1 Suction Connection .............................................................................................. 12
5.2.2 Discharge Connection .......................................................................................... 12
5.2.3 Cooling Water Connection ................................................................................... 13
5.2.4 Barrier Gas System Connection........................................................................... 14
5.3 Filling Oil ......................................................................................................................... 14
5.4 Filling Cooling Liquid ....................................................................................................... 16
5.5 Fitting the Coupling ......................................................................................................... 17
5.6 Electrical Connection ...................................................................................................... 18
5.6.1 Wiring Diagram Three-Phase Motor (Pump Drive) .............................................. 19
5.7 Electrical Connection of the Cooling Liquid Pump .......................................................... 20
5.7.1 Wiring Diagram Cooling Liquid Pump .................................................................. 20
5.8 Electrical Connection of the Monitoring Devices............................................................. 21
5.8.1 Wiring Diagram Resistance Thermometer ........................................................... 21
5.8.2 Wiring Diagram Vibration Diagnostic Unit ............................................................ 21
6 Commissioning ......................................................................................................................22
6.1 Recommendations on Operation .................................................................................... 23
6.1.1 Operating frequency............................................................................................. 23
6.1.2 Stop & Start .......................................................................................................... 23
6.1.3 Use with Argon ..................................................................................................... 23
6.2 Conveying Condensable Vapours................................................................................... 24
7 Maintenance ...........................................................................................................................24
7.1 Maintenance Schedule.................................................................................................... 25
7.2 Oil Level Inspection......................................................................................................... 26
7.3 Cooling Liquid Level Inspection ...................................................................................... 26
7.4 Oil Change ...................................................................................................................... 27
7.5 Cooling Liquid Change.................................................................................................... 30
8 Overhaul..................................................................................................................................34
9 Decommissioning ..................................................................................................................35
9.1 Dismantling and Disposal................................................................................................ 35

Table of Contents
Instruction Manual COBRA NC 2500 B WCV_EN_en 3
10 Spare Parts .............................................................................................................................35
11 Troubleshooting.....................................................................................................................35
12 Technical Data........................................................................................................................38
13 Cooling Liquid........................................................................................................................38
14 Oil ............................................................................................................................................38
15 EU Declaration of Conformity...............................................................................................39
16 UK Declaration of Conformity...............................................................................................40

1 | Safety
4 / 44 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 any-
thing 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 meth-
ods. Nevertheless, residual risks may remain. This instruction manual highlights po-
tential hazards where appropriate. 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 inju-
ries.
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
trouble-free operation.

Product Description | 2
Instruction Manual COBRA NC 2500 B WCV_EN_en 5 / 44
2 Product Description
CLV2
MP OSGODV
TSA2
OFP
CWIPHE CLP CWOCLD
INCLG
MTB
CLV1
CLF
OUT
EB EBCGU
MP OFP
OSG
OUTSI
ODV
CD
TSA1
SA
NP
TMBGS
ECP
TV
MP
BGS Barrier gas system CD Condensate drain
CGU Cooling gas unit (includ. air filter) 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 IN Suction connection with mesh screen
MP Magnetic plug MTB Motor terminal box
NP Nameplate ODV Oil drain valve
OFP Oil fill plug OSG Oil sight glass
OUT Discharge connection PHE Plate heat exchanger
SA Vibration transmitter (option) SI Silencer (option)
TM Thermometer TSA1 Resistance thermometer (cooling liquid
temperature)
TSA2 Resistance thermometer (exhaust gas
temperature)
TV Thermostatic valve
*For additional cooling liquid drain plugs (CLD), see Cooling Liquid Change [►30].

2 | Product Description
6 / 44 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 are rotating inside the cylinder. The pumped medium is trapped be-
tween the cylinder and screw chambers, compressed, and transported to the gas out-
let. During the compression process, the two screw rotors do not come into contact
with each other nor with the cylinder. There is no need for a lubrication or an operating
fluid in the compression chamber.
2.2 Application
The machine is intended for the suction of air and other dry, non-aggressive, non-toxic
and non-explosive 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 [►38].
The machine is suitable for continuous operation.
Permitted environmental conditions, see Technical Data [►38].
2.3 Start Controls
The machine comes without start controls. The control of the machine is to be provid-
ed in the course of installation.
The machine must be equipped with a variable-frequency drive.

Product Description | 2
Instruction Manual COBRA NC 2500 B WCV_EN_en 7 / 44
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 cham-
ber.
The motor of the cooling liquid pump must be electrically connected, see Electrical
Connection of the Cooling Liquid Pump [►20]
The cooling liquid is cooled by a plate heat exchanger (PHE) which must be connect-
ed 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 com-
pression 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
[►21].
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
[►21].
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
[►14].

2 | Product Description
8 / 44 Instruction Manual COBRA NC 2500 B WCV_EN_en
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 ma-
chine.
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 [►21].
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 / 44
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.
• Make sure that the eyebolt(s) (EB) is/are in faultless condition, fully screwed in and
tightened by hand.
3x
Machine weight:
see the technical data or the nameplate (NP)
Transport with a lifting hook
The air filter must be removed
before lifting the machine
l1 = ~430 mm
l2 & l3 = ~650 mm

4 | Storage
10 / 44 Instruction Manual COBRA NC 2500 B WCV_EN_en
Transport with a Forklift
Handling access must be from
the underneath 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.
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 [►27]. This protects the mechanical seals during a long storage. Use the
standard pump oil, see chapter Oil [►38].
• Before restarting the machine, drain the oil to the normal oil level, see “Oil draining”
in chapter Oil Change [►27].

Installation | 5
Instruction Manual COBRA NC 2500 B WCV_EN_en 11 / 44
5 Installation
5.1 Installation Conditions
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 [►38].
• Make sure that the environmental conditions comply with the protection class of the
motor and the electrical instruments.
• Make sure that the installation space or location is vented such that sufficient cool-
ing of the machine is provided.
• Make sure that cooling air inlets and outlets of the motor fan are not covered or ob-
structed 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 of 1° in
any direction is acceptable.
• Check the oil level, see Oil Level Inspection [►26].
• Check the cooling liquid level, see Cooling Liquid Level Inspection [►26].
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.
• Remove all protective covers before installation.
• Make sure that the connection lines cause no stress on the machine‘s connection; if
necessary 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 efficiency. Seek advice from your Busch representative.

5 | Installation
12 / 44 Instruction Manual COBRA NC 2500 B WCV_EN_en
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
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 discharged gas will flow without obstruction. Do not shut off or
throttle the discharge line or use it as a pressurised air source.
• 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 [►38].

Installation | 5
Instruction Manual COBRA NC 2500 B WCV_EN_en 13 / 44
5.2.3 Cooling Water Connection
CWO CWIPHE
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
°F
+10 ... +30
Required pressure differential across sup-
ply and return
bar ≥ 1
• To reduce the maintenance effort and ensure a long product lifetime we recom-
mend the following 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
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 | Installation
14 / 44 Instruction Manual COBRA NC 2500 B WCV_EN_en
5.2.4 Barrier Gas System Connection
Without nitrogen panel
PRV FRBGC MAN FME
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
pressure regulating valve (PRV)
bar 3
Filtration µm 5
Recommended flow rate SLM* 30
Air quality (only for air) Acc. to ISO
8573-1
Class 5.4.4.
* standard litre per minute
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.

Installation | 5
Instruction Manual COBRA NC 2500 B WCV_EN_en 15 / 44
For oil type and oil capacity see Technical Data [►38] and Oil [►38].
1
2
Busch Oil
3
MAX
MIN
3 mm
4
Check oil level
Oil filling at the motor side
1
2
Busch Oil
3
MAX
MIN
3 mm
4
Check oil level
Oil filling at the suction side

5 | Installation
16 / 44 Instruction Manual COBRA NC 2500 B WCV_EN_en
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.
5.4 Filling Cooling Liquid
For cooling liquid type and cooling liquid capacity see Technical Data [►38] and
Cooling Liquid [►38].
1
2
Cooling
liquid
Zitrec M-25
3
4
5
Cooling liquid filling Cooling liquid vent plug (CLV1)
Fill up to the top of the
vent orifice (CLV1)

Installation | 5
Instruction Manual COBRA NC 2500 B WCV_EN_en 17 / 44
3
2
MAX
MIN
Cooling
liquid
Zitrec M-25
1
Resume cooling liquid filling
5.5 Fitting the Coupling
2
3
E
1
Coupling hub (machine side)
Coupling hub (motor side)
Elastic insert
Radial screw
Max. admissible
torque: 10 Nm
Ring
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.

5 | Installation
18 / 44 Instruction Manual COBRA NC 2500 B WCV_EN_en
5.6 Electrical Connection
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.
• The electrical installation must comply with applicable national and international
standards.
• Provide a lockable disconnect switch on the power line so that the machine is com-
pletely secured during maintenance tasks.
• Provide an overload protection according to EN 60204-1 for the motor.
• Make sure that the motor of the machine will not be affected by electric or electro-
magnetic disturbance from the mains; if necessary seek advice from Busch.
• Connect the protective earth conductor.
• Electrically connect the motor.
• Make sure that the machine is started by a variable-frequency drive.
NOTICE
The admissible motor nominal speed exceeds the recommendation.
Risk of damage to the machine!
• Check the admissible motor nominal speed (nmax) on the nameplate of the machine
(NP).
• Make sure to comply with it.
• Consult the Technical Data [►38] to get more information.
NOTICE
The motor frequency is below 20 Hz.
Risk of damage to the machine!
• The motor nominal speed must always be higher than 1200 min-1 (20 Hz).
NOTICE
Incorrect connection.
Risk of damage to the motor!
• The wiring diagrams given below are typical. Check the inside of the terminal box
for motor connection instructions/diagrams.

Installation | 5
Instruction Manual COBRA NC 2500 B WCV_EN_en 19 / 44
5.6.1 Wiring Diagram Three-Phase Motor (Pump Drive)
Delta connection (low voltage): Star connection (high voltage):
NOTICE
Incorrect direction of rotation.
Risk of damage to the machine!
• Operation in the wrong direction of rotation can destroy the machine in a short time!
Prior to start-up, ensure that the machine is operated in the right direction.
The intended rotation direction of the motor is defined by the illustration below:
IN
• Jog the motor briefly.
• Watch the fan wheel of the motor and determine the direction of rotation just before
the fan wheel stops.
If the rotation of the motor must be changed:
• Switch any two of the motor phase wires.

5 | Installation
20 / 44 Instruction Manual COBRA NC 2500 B WCV_EN_en
5.7 Electrical Connection of the Cooling Liquid
Pump
DANGER
Live wires.
Risk of electrical shock.
• Electrical installation work must only be executed by qualified personnel.
• Provide an overload protection according to EN 60204-1 for the pump.
• Electrically connect the cooling liquid pump.
• Make sure that the cooling liquid pump is connected such that is running when the
machine is started.
5.7.1 Wiring Diagram Cooling Liquid Pump
230/400 VAC cooling liquid pump version:
Delta connection (low voltage): Star connection (high voltage):
• Make sure that the cooling liquid flows in the right direction according to the follow-
ing illustration.
Rotation direction
of the motor
Cooling liquid flow
direction
If the rotation of the motor must be changed:
• Switch any two of the motor phase wires.