BUSCH 7180551, Installation And Maintenance Instructions Manual

Page: 4 / 36

WARNING
When using toxic, inflammable and/or explosive gases, make sure
that the system corresponds in design to applicable local and
national safety regulations and that all applicable safety measures
are followed.
All product-specific safety regulations must be observed.
Solid particles must not get into the vacuum pump. Procedural errors
can result in the pump drawing in a certain quantity of liquid. If the
pump has drawn in liquid, a short drying time will be necessary at the
end of the process. In case a silencer (accessory) is fitted at the outlet:
u Drain the silencer (accessory)
The vacuum pump is thermally suitable for continuous operation at any
pressure between atmospheric pressure and ultimate pressure.
Principle of operation
The COBRA NC vacuum pumps operate according to the principle of
screw pumps. Two parallel screws (RT) rotate in opposite directions in
the pump body. Entering gases are trapped between the pitches of the
screws and the pump body. The gases are conveyed by the rotation of
the screws to the exhaust side where they are discharged.
The COBRA NC vacuum pump is driven by an air-cooled motor.
The single stage vacuum pump is equipped with the essential
supervisory and monitoring equipment. The vacuum pump is mounted
on a robust frame. The vacuum pump is equipped with a direct cooling
system.
The cooling system is complemented by an external heat exchanger,a
recirculation pump and a thermostatic valve which must be selected
and fitted by the manufacturer of the system.
A level switch (LS) supervises the level of the cooling liquid. When the
level switch (LS) detects a too low level for more than 30 seconds, the
pump must be stopped.
A vibration transmiter (SA) supervises the condition of the ball-bearings
which must be replaced when the set values are exceeded.
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
protection markings:
COBRA NC 400 B
Inside II 2G Ex h IIB T3 Gb X
1 2 3 4 5 6 7 8 9
1 Design approved according to ATEX Directive
2 Explosion protection inside the machine
3 Equipment group II (not for mining application)
4 Equipment category for explosive gases inside the machine
5 Type of protection
6 Explosion group inside the machine
7
Temperature class inside the machine (T2=300°C) ;
(T3=200°C) ; (T4=135°C)
8 Equipment protection level
9 Special conditions of use
Cooling
The vacuum pump is cooled by a cooling liquid (mix of water and
glycol) inside the cooling liquid chambers (CL) of the cylinder and the
motor side end plate of the cylinder (A-side) as well as the inlet side
end plate (B- side).
An external recirculating pump sends the cooling liquid to the external
heat exchanger and from that point back into the vacuum pump.
When using a plated heat exchanger, the secondary cooling circuit
must be regulated by a thermostatic valve.
During operation, the pressure loss between
r
1 -
r
2 must not exceed
0,17 bar at 50 Hz respectively 0,30 bar at 60 Hz. This means that pipes
with sufficiently large diameters must be chosen and flow resistance
should be limited.
When using an external air/water heat exchanger, the thermostatic
valve is not needed.
NOTE
The COBRA NC vacuum pumps are always shipped without oil,
cooling water and cooling liquid. Operation without any of these
lubricants will destroy the vacuum pump within a short period of
time.
Sealing
The COBRA NC vacuum pumps are equipped with mechanical seal on
the motor side (A-side) and mechanical seal on the inlet side (B-side) as
standard.
The mechanical seal on the motor side (A-side) is complemented by a
barrier gas system. Compressed air is connected to the barrier gas
system and the pressure regulating valve (BGR) for the barrier gas
pressure set to 3 bar over-pressure.
Accessories
A silencer or sound absorber (accessory) at the outlet of the pump
reduces the noise of the pump and collects any condensates.
A temperature sensor (TS) on the motor side (A-side) monitors the
cooling liquid temperature. If the temperature exceeds 65°C, the pump
must be inertised and stopped.
The pump is equipped with a gas ballast connection (GB) which can be
opened and closed with a ball valve.
On/ Off switch
The vacuum pump is delivered without on / off switch. The control of
the vacuum pump must be provided during installation.
Product Description
Page 4
r
1
TV
r
2
uP
TV - thermostatic valve control range 25 ... 65 °C
Danfoss AVTA, uP: Recirculation pump, WITA u55