BUSCH COBRA NX 0450 A User manual

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Instruction Manual
COBRA
Dry Screw Vacuum Pumps
NX 0450 A, NX 0650 A
(air-cooled version)
0870211160/-0001_en / Original instructions / Modifications reserved 17/11/2021

Table of Contents
2 / 40 Instruction Manual COBRA NX 0450-0650 A ACV_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 ................................................................................................................... 7
2.4 Standard Features ............................................................................................................ 7
2.4.1 Air Cooling ............................................................................................................7
2.4.2 Temperature Switch .............................................................................................. 7
2.4.3 Sealing Systems .....................................................................................................8
2.5 Optional Accessories ........................................................................................................ 8
2.5.1 Gas Ballast Valve ...................................................................................................8
2.5.2 Silencer.................................................................................................................. 8
2.5.3 Barrier Gas System................................................................................................. 8
3 Transport ..................................................................................................................................8
4 Storage .....................................................................................................................................9
5 Installation................................................................................................................................9
5.1 Installation Conditions...................................................................................................... 9
5.2 Connecting Lines / Pipes .................................................................................................. 10
5.2.1 Suction Connection ...............................................................................................11
5.2.2 Discharge Connection ........................................................................................... 11
5.2.3 Barrier Gas System Connection (Optional)............................................................. 12
5.3 Filling Oil.......................................................................................................................... 13
5.4 Cooling System Cover Removal........................................................................................ 15
5.5 Filling Cooling Liquid........................................................................................................ 16
5.6 Electrical Connection ........................................................................................................ 17
5.6.1 Wiring Diagram Three-Phase Motor (Pump Drive) ................................................ 18
5.7 Electrical Connection of the Monitoring Devices............................................................... 19
5.7.1 Wiring Diagram Temperature Switch..................................................................... 19
5.8 Electrical Connection of the Cooling System..................................................................... 19
5.8.1 Wiring Diagram Cooling System............................................................................20
6 Commissioning.........................................................................................................................20
6.1 Conveying Condensable Vapors....................................................................................... 21
7 Maintenance.............................................................................................................................22
7.1 Maintenance Schedule ..................................................................................................... 23
7.2 Oil Level Inspection.......................................................................................................... 23
7.3 Cooling Liquid Level Inspection ........................................................................................ 24
7.4 Cleaning the Inlet Screen.................................................................................................. 25
7.5 Cleaning the Gas Ballast Filter (Optional) ......................................................................... 25
7.6 Oil Change....................................................................................................................... 26
7.7 Cooling Liquid Change..................................................................................................... 29
8 Overhaul...................................................................................................................................31
9 Decommissioning.....................................................................................................................31
9.1 Dismantling and Disposal ................................................................................................. 31
10 Spare Parts................................................................................................................................32
11 Troubleshooting .......................................................................................................................32

Table of Contents
Instruction Manual COBRA NX 0450-0650 A ACV_EN_en 3
12 Technical Data..........................................................................................................................34
13 Cooling Liquid..........................................................................................................................34
14 Oil ............................................................................................................................................34
15 EU Declaration of Conformity...................................................................................................35
16 UK Declaration of Conformity ..................................................................................................36

1 | Safety
4 / 40 Instruction Manual COBRA NX 0450-0650 A ACV_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 meth-
ods. Nevertheless, residual risks may remain. This instruction manual highlights potential
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 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
trouble-free operation.

Product Description | 2
Instruction Manual COBRA NX 0450-0650 A ACV_EN_en 5 / 40
2 Product Description
EB IN, IS
OUT
PMR MP
BGRCLD
SI
OSG
GBOFPCLF
BGCNPODP
BGFOFP
OSG CLDODP CLP MP
OUTCD
AHE CLD BGMAF
TS2 TB
TS1
MTB
CLV1CLV2
AHE Air-water heat exchanger AF Axial fan
BGC Barrier gas connection BGF Barrier gas flow meter
BGM Barrier gas manometer BGR Barrier gas pressure regulator
CD Condensate drain CLD Cooling liquid drain plug
CLF Cooling liquid fill plug CLV1 Cooling liquid vent valve (heat exchanger)
CLV2 Cooling liquid vent plug (machine) CLP Cooling liquid pump
EB Eye bolt GB Gas ballast valve
IN Suction connection IS Inlet screen
MP Magnetic plug MTB Motor terminal box
NP Nameplate ODP Oil drain plug
OFP Oil fill plug OSG Oil sight glass
OUT Discharge connection PMR Plug for manual rotation of rotors
SI Silencer TB Terminal box (cooling system)
TS1 Temperature switch (machine) TS2 Temperature switch (cooling system)

2 | Product Description
6 / 40 Instruction Manual COBRA NX 0450-0650 A ACV_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 outlet.
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 [►34].
The machine is suitable for continuous operation.
Permitted environmental conditions, see Technical Data [►34].

Product Description | 2
Instruction Manual COBRA NX 0450-0650 A ACV_EN_en 7 / 40
NOTICE
Chemical compatibility of the process gases with the machine component materials.
Risk of corrosion inside the compression chamber which can reduce performance and
its lifetime!
• Check if the process gases are compatible with those following materials:
- Cast iron
- Steel
- Aluminium
- Fluoroelastomer (FKM/FPM)
• In doubt, please contact your Busch representative.
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 can be optionally equipped with a starter unit or a variable-frequency drive.
2.4 Standard Features
2.4.1 Air 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 cooling liquid is cooled by an air-water heat exchanger (AHE).
IN
AHE
M
TS2
TS1
T1
Tcooling liquid
MOT3
OUT
M
CPL MOT1
CLP
M
MOT2
AHE Air-water heat exchanger CLP Cooling liquid pump
CPL Coupling IN Suction connection
MOT1 Motor (pump) MOT2 Motor (cooling liquid pump)
MOT3 Motor (Air-water heat exchanger) OUT Discharge connection
TS Temperature switch
2.4.2 Temperature Switch
The temperature switch monitors the cooling liquid temperature of the machine.
The temperature switch has one switch point :
Switch point 1 (T1) Trip, the machine must be stopped

3 | Transport
8 / 40 Instruction Manual COBRA NX 0450-0650 A ACV_EN_en
2.4.3 Sealing Systems
The machine is equipped with labyrinth seals on the motor side and suction side.
Sealing systems prevent the process gas going to the bearings chambers.
Depending on the application, the sealing systems efficiency can be improved with a
barrier gas system, see Barrier Gas System [►8].
2.5 Optional Accessories
2.5.1 Gas Ballast Valve
The gas ballast valve mixes the process gas with a limited quantity of ambient air to
counteract the condensation of vapour inside the machine.
The gas ballast valve has an influence on the ultimate pressure of the machine, see Tech-
nical Data [►34].
2.5.2 Silencer
A silencer at the discharge connection (OUT) can be provided to reduce the exhaust gas
noise.
2.5.3 Barrier Gas System
The barrier gas system allows the supply of compressed air or nitrogen into the motor
side shaft seals in order to improve the sealing efficiency.
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 in-
gress 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.

Storage | 4
Instruction Manual COBRA NX 0450-0650 A ACV_EN_en 9 / 40
Machine weight: see the technical data or the nameplate (NP)
• Make sure that each of the slings used to lift the machine has a minimum length of
400 mm.
• Make sure that the length of each sling is exactly the same.
• 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.
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.

5 | Installation
10 / 40 Instruction Manual COBRA NX 0450-0650 A ACV_EN_en
~20 cm
~20 cm
~50 cm
~50 cm
• Make sure that the environment of the machine is not potentially explosive.
• Make sure that the ambient conditions comply with the Technical Data [►34].
• 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 cooling
of the machine is provided.
• Make sure that cooling air inlets and outlets 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 of 1° in
any direction is acceptable.
• Check the oil level, see Oil Level Inspection [►23].
• Check the cooling liquid level, see Cooling Liquid Level Inspection [►24].
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
• 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.

Installation | 5
Instruction Manual COBRA NX 0450-0650 A ACV_EN_en 11 / 40
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):
– G3
– ISO DN100, DIN 28404
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
Discharge variants (without silencer)
Connection size(s):
At the machine discharge connection:
– G2 for NX 0450 A, horizontal (orientable 180°)
– G3 for NX 0650 A, horizontal (orientable 180°)
– DN63 ISO-K, DIN 28404 for NX 0450 A, vertical (without discharge elbow)
– ISO DN100, DIN 28404 for NX 0650 A, vertical (without discharge elbow)
At the silencer (SI) discharge connection (Optional):
– G2 for NX 0450 A, G3 for NX 0650 A, horizontal

5 | Installation
12 / 40 Instruction Manual COBRA NX 0450-0650 A ACV_EN_en
• 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 con-
nection (OUT) does not exceed the maximum allowable discharge pressure, see Tech-
nical Data [►34].
5.2.3 Barrier Gas System Connection (Optional)
PRV FMEBGCMAN
BGC Barrier gas connection FME Flow meter
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(a) 3
Filtration µm 5
Recommended flow rate SLM* 10 ... 15forNX0450A
15 ... 20forNX0650A
Air quality (only for air) Acc. to ISO
8573-1
Class 5.4.4.
* standard litre per minute

Installation | 5
Instruction Manual COBRA NX 0450-0650 A ACV_EN_en 13 / 40
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 [►34] and Oil [►34].
Check oil level
Oil filling at the motor side

5 | Installation
14 / 40 Instruction Manual COBRA NX 0450-0650 A ACV_EN_en
Check oil level
Oil filling at the inlet side
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.

Installation | 5
Instruction Manual COBRA NX 0450-0650 A ACV_EN_en 15 / 40
5.4 Cooling System Cover Removal
NOTE
Before filling or changing the cooling liquid and electrically connecting the cooling sys-
tem.
• Remove the cooling system cover.

5 | Installation
16 / 40 Instruction Manual COBRA NX 0450-0650 A ACV_EN_en
5.5 Filling Cooling Liquid
The machine is already dispatched with cooling liquid.
If it is not the case:
• Electrically connect the cooling system, see Electrical Connection of the Cooling
System [►19].
• Fill in the machine with cooling liquid according to the following procedure.
For cooling liquid type and cooling liquid capacity see Technical Data [►34] and
Cooling Liquid [►34].
Resume cooling
liquid filling
Close the cooling liquid
vent valve (CLV1)
when the cooling
liquid is spilling out*
Switch on the
cooling liquid
pump (CLP)
Switch off the
cooling liquid
pump (CLP)
Open the cooling
liquid vent valves
(CLV1, CLV2)
Close the cooling
liquid vent valve
(CLV2) when the
cooling liquid is
spilling out*
Vent air from the
cooling system
*This illustration shows the
COBRA NX 0650 A ACV.
For the COBRA NX 0450 A ACV,
invert the order of cooling liquid
vent valve closings: first close
CLV1 then CLV2.

Installation | 5
Instruction Manual COBRA NX 0450-0650 A ACV_EN_en 17 / 40
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.
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 [►34] 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.

5 | Installation
18 / 40 Instruction Manual COBRA NX 0450-0650 A ACV_EN_en
5.6.1 Wiring Diagram Three-Phase Motor (Pump Drive)
Delta connection (low voltage): Star connection (high voltage):
Double star connection, multi-voltage
motor with 12 pins (low voltage):
4
4
4
Star connection, multi-voltage motor
with 12 pins (high voltage):
4
4
4
Delta connection, multi-voltage motor
with 12 pins (middle voltage):
4
4
4
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:
• 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.

Installation | 5
Instruction Manual COBRA NX 0450-0650 A ACV_EN_en 19 / 40
5.7 Electrical Connection of the Monitoring Devices
NOTE
In order to prevent potential nuisance alarms, Busch recommends that the control system
is configured with a time delay of at least 20 seconds.
5.7.1 Wiring Diagram Temperature Switch
Part no.: 0651563762
Connector: M12x1, 4-pin
U = ≤ 250 V AC/DC (50/60 Hz) ; I = ≤ 1 A
Switch point:
Ttrip = T1 ► pin 3 + 4 1 = Brown ; 2 = White ;
3 = Blue ; 4 = Black
5.8 Electrical Connection of the Cooling System
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.
• Provide an overload protection according to EN 60204-1 for the fan motor.
• Electrically connect the cooling system, according to the wiring diagram, see Wiring
Diagram Cooling System [►20].
• Make sure that the cooling system is in operation when the machine is started.
NOTE
In operation, the fan only starts as soon as a certain operating temperature is reached.
• Make sure that the air flow blows in the right direction according to the following il-
lustration.
If the rotation of the motor must be changed:
• Switch any two of the power supply.

6 | Commissioning
20 / 40 Instruction Manual COBRA NX 0450-0650 A ACV_EN_en
5.8.1 Wiring Diagram Cooling System
NOTE
The wiring diagram of the cooling system might be specific to the order.
• Please refer to the specific wiring diagram supplied inside the terminal box (TB).
Wiring diagram
6 Commissioning
NOTICE
The machine can be shipped without oil.
Operation without oil will ruin the machine in short time!
• Prior to commissioning, the machine must be filled with oil, see Filling Oil [►13].
NOTICE
The machine can be shipped without cooling liquid.
Operation without cooling liquid will ruin the machine in short time!
• Prior to commissioning, the machine must be filled with cooling liquid, see Filling
Cooling Liquid [►16].
NOTICE
Lubricating a dry running machine (compression chamber).
Risk of damage to the machine!
• Do not lubricate the compression chamber of the machine with oil or grease.