The COBRA BC 0601 G vacuum pumps are COBRA NW screw
vacuum pumps with cooling water and nitrogen circuits.
The COBRA NS screw vacuum pumps are driven by water-cooled
motors.
Principle of DP vacuum pumps
The COBRA NS screw vacuum pumps work by the principle of spiral
pumps. Two parallel screws (8) rotate in opposite directions in the
pump body. Entering gases are trapped between the flights of the
screws and the pump body. The gases are conveyed by the rotation of
the screws to the exhaust, where they are discharged.
Principle of MB vacuum pumps
The Roots vacuum pumps operate according to the approved principle
of the Roots type machine. Operation is both simple and effective.
Two lobes (9) with identical profiles rotate in opposition directions with
in a casing. As they rotate, gas is drawn into the space between each
lobe and the casing where it is trapped and by the rotation pushed out
into the discharge. This action is repeated twice for each revolution of
each lobe and therefore four times for each revolution of the drive
shaft. There is no mechanical contact between lobes and cylinder. So
no oil lubrication is required.
The drive motor of roots pump is a water cooled canned motor.
Gas flow checks
A pressure sensor PSA at the discharge monitors the discharge
pressure. If the pressure reaches more than the limit value (alarm,
preset at the factory: 0.2 bar), the purge cycle starts.
Oil circuit
Since the complete operating principle works without contact, no oil
circuit is needed in the work area.
Cooling
The vacuum pump is cooled by
–
a direct cooling water circuit in the motors and the DP and MB
transmission casing. The flow regulating valve CWR of cooling
water is preset on 3-4 l/min at the factory. The water cools in the
DP and MB pumps motors, the one frequency inverter (VFD 1)
and the drive/ pump transmission DP system.
–
a direct cooling water circuit in the rear bearing (for exceptionally
cool running in option).
NOTE
: The COBRA BC 0601 G vacuum pumps are principally dispatched
without oil already in the vacuum pump but, without cooling water.
Before vacuum pump first startup, control the oil level and the cooling
liquid level. In the event of absence of one or the other
of these lubricants, please carry out the filling (please refer to the
various chapters of filling). Do not forget to connect the cooling water
supply before the first startup. Operation without these coolants can
result in damage to the vacuum pump.
Nitrogen system
The nitrogen system can be used in a number of different ways :
–
nitrogen is used as dilution gas. It is injected inside the cylinder on
two different places. Nitrogen flow injected in the middle hole is
preset at 2 l/ min and can be adjusted with valve DGR 2, depending
on the application. Nitrogen flow injected in the hole on cylinder
endplate side is preset at 10 l/ min and can be adjusted with valve
DGR 1, depending on the application. When flow is too low a
warning then an alarm signal is generated by flowmeter DGF to the
PLC. Status of the pump depends on the alarm function set by user
(factory setting : None, pump continues running with an alarm).
Dilution improves the screwsfunctioning, especially when sucking
corrosive gases.
–
nitrogen is used as sealing gas. The nitrogen is injected between the
transmission and the process gas to achieve good closeness. The
Nitrogen flow used for the sealing is set by two chips (
ɸ
). With a
pressure of 1,5 bar, the flow is around 8-10 l/min.
Optional functions/ Use of available
accessories
A pressure sensor (PSA) mounted at the exhaust , controls the
overpressure at the exhaust. If overpressure is above 0,3 bar, pressure
sensor gives a warning then an alarm signal. Status of the pump
depends on the alarm function set by user (factory setting : None,
pump continues running with an alarm).
A temperature sensor PT100 (TS 4) mounted on the cylinder, measures
the temperature inside the cylinder (DP).
A silencer or sound absorber (accessory) at the exhaust reduces the
noise of the pump and collects any condensate.
A leak-protection non-return valve (optional) at the exhaust traps the
condensate in the pump when the pump is switched off.
The LCD controller processes the data of the sensors as follows:
–
PSA: exhaust pressure
–
TS 4: temperature inside the cylinder DP
–
MOT 1 and MOT 2: DP and MB current and speed
–
DGF: nitrogen flow rate, dilution
–
CWM: cooling water flow rate in motors/ transmission/ frequency
inverters
See "Installation and Maintenance Instructions, Busch PLC and BuschLCD (No.
0870758077)".
On/ Off switch
The vacuum pump is delivered with a circuit breaker. The function start/ stop can
be done in Local by using the LCD controller or in Remote by the production
machine.
Versions
Further vacuum pump descriptions state the nominal displacement and the
design level.
Example: BC 0601 G
BC = standard version
601 = 600 m
3
/h
G
= Design
Product description
Page 6
BC 0601 G
0870235875
(En)
Summary of Contents for COBRA BC 0601 G
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