Operating; Start Up Of The Pump; Inerting Process; Operation - BUSCH COBRA NC 400 B Supplément Au Manuel D'installation Et De Maintenance

Operating

Start up of the pump

Before the actual start-up of the vacuum pump, the inside of the va-
cuum pump has to be inerted, if it cannot be excluded that an explo-
sive mixture is present inside the pump. This is generally done by
flushing the pump with a non explosive gas, such as air or nitrogen,
whilst the pump is stopped and its inlet closed.

Inerting process

l Close the pump inlet (suction valve MV1)
l Feed non-explosive gas through the flushing gas connection, suc-
tion side
l Non-explosive gas volume flow:
u NC 400 B : ³ 100 liter/ min
l Inertise for 200 seconds, after that the gas supply can be shut off
and the inerting is completed.
After inerting, the pump can be started. The seal on the exhaust side
(motor side) can be supplied with a barrier gas, such as air or nitrogen.
On starting the motor, major vibrations can briefly occur. Consequen-
tly, a possible alarm of the vibration pickup (SA+/ 0701) up to 10 se-
conds after starting the motor does not need to be taken into
consideration.
If the application requires even higher operating temperatures, more
flushing gas can be added. After having reached the operating tempe-
rature, the suction valve MV1 can be released. As some suction valves
can open jerkily, it is admissible not to consider a possible alarm of the
vibration pickup during the opening of the suction valve.

Operation

During operation the pump runs continually. No other connection will
be activated.
The vacuum pump has to be stopped immediately if one of the moni-
toring elements exceeds the set value defined in "COBRA ATEX
Catalogue".
WARNING
Obligatory minimal surveillance for vacuum pumps certified:
Inside II 2G Ex h IIB T3 Gb X
Outside II 2G Ex h IIB/IIC T3 Gb X
- Cooling liquid temperature TSA+/ 0102
- Temperature of the exhaust gases TSA+/ 0103
- Acceleration of the pump SA+/ 0701
- Cooling liquid level LS-/ 0203
Obligatory minimal surveillance for vacuum pumps certified:
Inside II 3G Ex h IIB T3 Gc X
Outside II 3G Ex h IIB/IIC T3 Gc X
- Temperature of the cooling liquid TSA+/ 0102
The customer must operate the pump in accordance with explosion
protection regulations.

Idle operation

Before switching off the vacuum pump, the inside of the vacuum
pump must be inerted, if it cannot be excluded that an explosive mix-
ture is present inside the pump. For the inerting process, the vacuum
pump must be operated a certain time during which it will be flushed
with a non-explosive gas. This can be done with non-explosive am-
bient air by opening the pump inlet, or with the help of the optional li-
quid purge.

Inerting process with purge gas

On starting the motor, some major vibrations can briefly occur. Conse-
quently, a possible alarm of the vibration pickup (SA+/ 0701) does not
need to be taken into consideration.
l Run the pump
Description
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l Close the pump inlet after the end of the process (suction flange
MV1)
l Feed non explosive gas through the flushing gas connection, suc-
tion side
l Non explosive gas volume flow:
u NC 400 B : ³ 100 liter/ min
l Inertise for at least 200 seconds, after that the gas supply can be
shut off and the inerting process is completed
l Switch off the pump, close the valves MV2, MV3, MV5, MV7
In case of built-up of condensates inside the pump due to the process,
the time for inertising should be extended to a minimum of 10 minu-
tes, which will dry the pump.
In case the pump is to be flushed with liquid, the optional liquid purge
should be done at a reduced speed (10 Hz) and after the inerting pro-
cess. The vacuum pump works with internal compression and can the-
refore only take a limited amount of fluid, which is determined by the
pipe diameter.

Flushing procedure with flushing liquid

l Inertise the pump
l Run the pump (max. 10 Hz)
l Close the pump inlet after the end of the process (suction valve
MV1)
l Feed flushing liquid through the flushing liquid connection, suction
side (open MV6)
l The flushing time and quantity of liquid depends on the process
and on experience
l Close MV6 after the flushing process
l Dry the pump with flushing gas for a minimum of 10 minutes, see
inerting process
l Switch off the pump and close all valves

Trip function

When a dysfunction occurs on the screw vacuum pump, it must be
stopped immediately. Close the suction valve MV1 immediately in or-
der to avoid the ventilation of the recipient via the screw vacuum
pump. The pump will then have to be inerted immediately.

Shutdown procedure

l A problem has been flagged up by a monitoring element during
the operation of the pump
l Close the suction valve MV1 immediately and simultaneously sup-
ply non explosive gas through the flushing gas connection, suction
side
l Switch off the vacuum pump (motor)
l Non-explosive gas volume flow:
u NC 400 B : ³ 100 liter/ min
l Inertise for at least 200 seconds, after that shut off the gas supply
and the inerting process is completed
l Switch off the pump and close the valves MV2, MV3, MV5, MV7
Before restarting the pump, the cause of the problem has to be found
and resolved. This is particularly important when TSA+/ 0103, TSA+/
0102, PSA+/ 0301 (option), LS-/ 0203 or SA+/ 0701 have indicated
the problem.
The vacuum pump must be installed in such a way as to prevent any
return of gas or liquid drawn medium to get back into the pump when
the pump stops.

Protection against explosions

The vacuum pump COBRA NC 400 B conforms to European Directive
2014/34/EU.
The vacuum pump is provided with one of the following explosion pro-
tection markings: