BUSCH COBRA NF 0750 A User manual

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Instruction Manual
COBRA
Dry Screw Vacuum Pumps
NF 0750 A, NF 0950 A
Water-Cooled Version
0870232965/-0001_en / Original instructions / Modifications reserved 10/05/2021
Ateliers Busch S.A.
Zone industrielle, 2906 Chevenez
Switzerland

Table of Contents
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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 Water Cooling.......................................................................................................7
2.4.2 Temperature Switch .............................................................................................. 7
2.4.3 Sealing Systems .....................................................................................................7
2.5 Optional Accessories ........................................................................................................ 8
2.5.1 Gas Ballast Valve ...................................................................................................8
2.5.2 Silencer.................................................................................................................. 8
2.5.3 Barrier Gas System................................................................................................. 8
2.5.4 Inlet Filter ..............................................................................................................8
3 Transport ..................................................................................................................................9
4 Storage .....................................................................................................................................10
5 Installation................................................................................................................................10
5.1 Installation Conditions...................................................................................................... 10
5.2 Connecting Lines / Pipes .................................................................................................. 11
5.2.1 Suction Connection ...............................................................................................11
5.2.2 Discharge Connection ........................................................................................... 12
5.2.3 Cooling Water Connection ....................................................................................12
5.2.4 Barrier Gas System Connection (Optional)............................................................. 13
5.3 Filling Oil.......................................................................................................................... 14
5.4 Electrical Connection ........................................................................................................ 16
5.4.1 Wiring Diagram Three-Phase Motor (Pump Drive) ................................................ 17
5.5 Electrical Connection of the Monitoring Devices............................................................... 18
5.5.1 Wiring Diagram Temperature Switch..................................................................... 18
6 Commissioning.........................................................................................................................18
6.1 Start Procedure ................................................................................................................ 20
6.2 Shutdown Procedure........................................................................................................ 21
7 Maintenance.............................................................................................................................22
7.1 Maintenance Schedule ..................................................................................................... 23
7.2 Oil Level Inspection.......................................................................................................... 24
7.3 Cleaning the Inlet Screen.................................................................................................. 25
7.3.1 Cleaning the Inlet Screen with Vertical Flange G3 or DN100 ................................. 25
7.3.2 Cleaning the Inlet Screen with Horizontal Flange G3 ............................................. 25
7.3.3 Cleaning the Inlet Screen with Double Flange G2 .................................................. 26
7.4 Cleaning the Gas Ballast Filter (Optional) ......................................................................... 26
7.5 Oil Change....................................................................................................................... 27
8 Overhaul...................................................................................................................................30
9 Decommissioning.....................................................................................................................30
9.1 Dismantling and Disposal ................................................................................................. 30
10 Spare Parts................................................................................................................................31
11 Troubleshooting .......................................................................................................................31
12 Technical Data..........................................................................................................................33

Table of Contents
0870232965_NF0750A_NF0950A_WCV_-0001_IM_en 3
13 Oil ............................................................................................................................................33
14 EU Declaration of Conformity...................................................................................................34

1 | Safety
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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.
WARNING
... indicates a potentially dangerous situation related to the presence of an oxygen level
of more than 21%.

Product Description | 2
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2 Product Description
EB IN, IS
MTB
PMR MP
CWD
OSG
TS CWO
ODP
OFP
CWDODPOSG
CWI NP
MP
OFP
SI OUT
GB
CWD Cooling water drain plug CWI Cooling water inlet
CWO Cooling water outlet 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
TS Temperature switch
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 | Product Description
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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
between 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 [►33].
The machine is suitable for continuous operation.
Permitted environmental conditions, see Technical Data [►33].
A specific Oxygen Version (see nameplate), can convey process gas
with > 21% vol. oxygen.
The following warning and precautions additionally apply for the
Oxygen Version if process gas with > 21% vol. is drawn:
• The barrier gas system is obligatory (see Sealing Systems
[►7] and Barrier Gas System [►8]).
• Installation conditions: The installation area must be ventilated in
such a way so as to prevent unacceptable levels of oxygen (see
Installation Conditions).
• Only use an oil type which has been approved and recommen-
ded by Busch for oxygen applications (see Filling Oil [►14]).
• Follow the additional commissioning instructions (see Commis-
sioning [►18]).
• Follow the additional maintenance instructions (see Maintenance
[►22] and Oil Change [►27]).
• Only use Busch genuine spare parts (see Spare Parts [►31]).

Product Description | 2
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Pump nameplate of Oxygen version :
Danger : Pump Version for Oxygen Service !
Follow all warnings and precautions of the
instruction manual
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
- Stainless 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 must be equipped with a variable-frequency drive.
2.4 Standard Features
2.4.1 Water Cooling
The machine is cooled by a cooling water circuit in the cylinder cover, cylinder and in the
motor.
2.4.2 Temperature Switch
The temperature switch monitors the cooling water temperature of the machine.
The temperature switch has one switch point:
Switch point T = 70°C Trip, the machine must be stopped, pin 1+2 (see Electrical
Connection of the Monitoring Devices [►18]).
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 | Product Description
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WARNING
The barrier gas system is obligatory for the suction of process gas with > 21% vol. oxy-
gen.
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 [►33].
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.
Obligatory for the suction of process gas with > 21% vol. oxygen.
2.5.4 Inlet Filter
The inlet filter protects the machine against dust and other solids in the process gas. The
inlet filter is available with a cartridge.
Connection size: G3'

Transport | 3
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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.
Machine weight:
see the technical data or the nameplate (NP)
• Check the machine for transport damage.
If the machine is secured to a base plate:
• Remove the machine from the base plate.

4 | Storage
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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!
5 Installation
WARNING
Lack of oxygen regulation knowledge.
Risk of fire!
• Installation, commissioning and maintenance must only be carried out by qualified
personnel who are informed about the applicable safety regulations and trained in the
handling of oxygen.
• Accident prevention regulations or methods must imperatively be complied with.
Seek further information:
- European Industrial Gases Association “EIGA” www.eiga.eu (EIGA SAG NL 79/04).
- Berufsgenossenschaft Rohstoffe und chemische Industrie "BG RCI” www.bgrci.de
(Merkblatt M 034 Sauerstoff).
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 [►33].
• Make sure that the environmental conditions comply with the protection class of the
motor and the electrical instruments.
• 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 [►24].
• Make sure that the cooling water complies with the requirements, see Cooling Water
Connection [►12].

Installation | 5
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WARNING
The machine is not absolutely gas tight.
Risk of fire!
• The installation area must be aired in such a way so as to prevent unacceptable levels
of oxygen.
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.
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.
Several executions are available and typically include a mesh screen:
Connection size(s):
– G3, vertical or horizontal
– 2 x G2, horizontal
– ISO DN100, DIN 28404, vertical

5 | Installation
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5.2.2 Discharge Connection
Connection size(s):
At the silencer (SI) discharge connection:
– G3, horizontal
• 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 [►33].
5.2.3 Cooling Water Connection
CWI
CWO
CWI Cooling water inlet CWO Cooling water outlet
• 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 8 ... 16
Water pressure bar 1 ... 6
Supply temperature °C +5 ... +30
Required pressure differential across supply
and return
bar ≥ 1

Installation | 5
0870232965_NF0750A_NF0950A_WCV_-0001_IM_en 13 / 36
• To reduce the maintenance effort and ensure a long product lifetime we recommend
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 and cast iron
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 (Optional)
Obligatory for the suction of process gas with > 21% vol. oxygen.
(Oxygen > 21% vol.)
PRV FME
BGC
MAN
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

5 | Installation
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• 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* 15 ... 20
* 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.
WARNING
Use of an inappropriate oil.
Process gas with > 21% vol. oxygen, risk of fire!
• Only use an oil type which has previously been approved and recommended by
Busch.

Installation | 5
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For oil type and oil capacity see Technical Data [►33] and Oil [►33].
1
2
Busch Oil
MAX
MIN
3
4
Oil filling at the motor side
Check oil level
1
2
Busch Oil
MAX
MIN
3
4
Oil filling at the inlet side
Check oil level
When the oil filling is achieved:
• Write down the oil change date on the sticker.

5 | Installation
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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 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 [►33] 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).

Installation | 5
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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.
5.4.1 Wiring Diagram Three-Phase Motor (Pump Drive)
• Make sure that you select the proper frequency drive according to the motor specific-
ations.
• Connect the motor to your external frequency drive according to the operating in-
structions of your external frequency drive.
• Connect the motor cables as shown in the below wiring diagram.
NF 0950 A
Delta connection (low voltage): Star connection (high voltage):
NF 0750 A
Double star connection (low voltage):
T1
T6T3
T5T8
T4
T2
T7
T9
Star connection (high voltage):
T1
T6T3
T5T8
T4
T2
T7
T9
Connection of motor thermistors (3xPTC)
(recommended):
P1 P2
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:

6 | Commissioning
18 / 36 0870232965_NF0750A_NF0950A_WCV_-0001_IM_en
IN
• Jog the motor briefly.
• With a phase rotation tester, check if the wiring corresponds to the correct direction of
rotation.
If the rotation of the motor must be changed:
• Switch any two of the motor phase wires.
• Connect the motor temperature protection (Thermistors PTC. 3 x 155°C).
• Motor terminal box cable entries:
– 2 x M25 x 1.5
– 1 x M16 x 1.5
5.5 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.
5.5.1 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 = 70° C ► pin 1 + 2
1 2
4 3
2
1
T
1 = Brown ; 2 = White ;
3 = Blue ; 4 = Black
6 Commissioning
WARNING
Lack of oxygen regulation knowledge.
Risk of fire!
• Installation, commissioning and maintenance must only be carried out by qualified
personnel who are informed about the applicable safety regulations and trained in the
handling of oxygen.
• Accident prevention regulations or methods must imperatively be complied with.
Seek further information:
- European Industrial Gases Association “EIGA” www.eiga.eu (EIGA SAG NL 79/04).
- Berufsgenossenschaft Rohstoffe und chemische Industrie "BG RCI” www.bgrci.de
(Merkblatt M 034 Sauerstoff).

Commissioning | 6
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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 [►14].
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.
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.
CAUTION
During operation the surface of the machine may reach temperatures of more than
70°C.
Risk of burns!
• Avoid contact with the machine during and directly after operation.
CAUTION
Noise of running machine.
Risk of damage to hearing!
If persons are present in the vicinity of a non noise insulated machine over extended
periods:
• Make sure that ear protection is being used.
• Make sure that the installation conditions (see Installation Conditions) are met.
• Turn on the water supply.
If the machine is equipped with a barrier gas system:
• Turn on the barrier gas supply.
• Adjust the barrier gas pressure.
• Switch on the machine (see Start Procedure [►20] and Shutdown Procedure
[►21]).
• Make sure that the operating conditions comply with the Technical Data [►33].
• After a few minutes of operation, perform an Oil Level Inspection [►24].
As soon as the machine is operated under normal operating conditions:
• Measure the motor current and record it as reference for future maintenance and
troubleshooting work.

6 | Commissioning
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6.1 Start Procedure
Temperature switch
70°C
START
Procedure
YES
Stop the machine
NO
Cooling water outlet
temperature
YES
NO
Start the machine
Active or inactive
Barrier gas flow
15-20 SLM (option)
Active or inactive
Cooling water supply
8-16 l/min, 1-6 bar,
5 - 30°C
Open barrier
gas supply -
visual confirmation
Temperature
switch closed ?
Machine in operation ?
Stop the machine
YES
NO
Ramp up time:
150 seconds
Minimum speed: 20Hz
Maximum speed:
60Hz (NF 0750 A)
72Hz (NF 0950 A)
Emergency
STOP button
activated ?
Open cooling
water supply