Bypass Option; Operation/ Running; Start Up Of The Pump; Running - Busch COBRA NC 0100 B Installation Und Betriebsanleitung

Bypass Option

To avoid the loss of suction capacity of the pump COBRA NC through
the flame-arresters on the suction side at low suction pressures, Ateliers
Busch S.A. offers a Bypass in option. The screw vacuum pump is
delivered with flame-arresters for the explosion group IIB3, as well as
with a Bypass connection on the suction side, with a ball valve DN50.
The ball valve is equipped with a limit switch (GS/ 0601).

Operation/ Running

Start up of the pump

After the start up of the pump, the nitrogen valve MV2 opens first; 3
seconds later, the screw vacuum pump starts up. The pump warms up
until it reaches the adjusted running temperature. After the starting,
the flushing gas valve MV3 opens for a pre-determined period (min. 5
minutes). After the running temperature is reached, the suction valve
MV1 is released by a signal given by the resistance thermometer PT
100 TS+/ 0102. The suction valve can then be opened. As the process
begins, the pressure in the recipients will decreased and the flushing
gas valve MV3 should be closed before the suction valve MV1 opens.

Running

During the running, the pump turns continually. No other connection
will be activated.
The customer must operate the pump in accordance with explosion
protection regulations.

Bypass Option : Installation and Operation

To complete the Bypass equipment, the pipe-work should at least
correspond to DN40 (COBRA NC 0100 B) or DN50 (COBRA NC 0200/
0300 B). For a category 1 equipment (zone 0) two pressure sensors
must be installed on the suction side, see flow sheet. The exact position
and the space towards the flame-arrester aren't prescribed. However
it's useful to install both pressure sensors, one close beside to the
other. For a category 2 equipment (zone 1) one pressure sensor is
sufficient.
The control of the Bypass valve has to ensure that the valve is closed
with pressures > 100 hPa. The limit switch GS/ 0601 must confirm the
closing of the valve. In case of pressures £ 100 hPa, the Bypass can be
opened. If both pressure sensors measure on adjustment a Dp > 10
hPa, e.g. because of a defect on a sensor, the Bypass valve must close
automatically.
Description
Seite/ Page/ Page 14
The connected vacuum system must have an explosion resistance > 1
bar !

Empty running

For the gas flushing or inertisation, the pump should run empty for a
while. At the end of the process, the suction valve MV1 should be
closed first. As the vacuum pump runs against the end pressure,
approx. 3 seconds later, the valve of the flushing gas MV3 opens for at
least 10 minutes for the expulsion of the solvent and the drying of the
pump. After that, the pump can be stopped and the nitrogen valve
MV2 and the water cooling valve MV4 closed.
Depending on the purge medium, the optional liquid purge should
take place at a reduced speed (10 Hz). The empty pump works with
internal compression and can therefore only take a limited amount of
fluid, which is determined by the pipe section.

Trip procedure

When a dysfunction occurs on the screw vacuum pump, it should
immediately be stopped. Close without delay the suction valve MV1 in
order to avoid the ventilation of the recipient via the screw vacuum
pump. If necessary, the nitrogen valve MV2 and the flushing gas valve
MV3 can stay open for a certain time for the inertisation of the pump.
Both valves should close instantaneously after the flushing of the pump
and the pipe on the pressure side. If the problem is solved, the
installation can be started again. If the running temperature of the
vacuum pump is still there, the work can continue. If the pump has
cooled down in the meantime, the starting procedure according to
"Start up" should be executed again.
The vacuum pump should be installed such a way than when the
pump stops, a rear current resp. a reflux of the drawn medium isn't
possible.
If the contacts TSA+/ 0101, TSA+/ 0102, TSA+/ 0103, or PSA+/ 0301
are triggered, check any accumulation of dirt and / or damage of the
flame arrester filters before starting again; if necessary or in doubt
replace the filters or clean them as and when appropriate.

Protection against explosions

The vacuum pumps COBRA NC 0100 ... 0300 B are conformable to
the European directive 2014/34/EU.
The vacuum pumps are provided with one of the following
characteristics for the protection against the explosions:
COBRA NC 0100 B
inside (i)
II
outside (o)
or
inside (i)
II
outside( o)
For the adjustment of the temperature class, imperatively refer to
"Adjustment of the thermostatic valve (option) and adjustment of the
temperature class".
1G c IIB3 T4
2G c IIB T4
1G c IIB3 T4
2G c IIC T4
NC 0100...0300 B, Cat. 1
0870549526 (En/ De/ Fr)