BUSCH COBRA NS 0070-0160 C Installation And Maintenance Instructions Manual Download Page 4

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Product description

Use

The COBRA NS vacuum pumps are designed for use in the field of
industrial applications and similar industries.

They can be used to draw gases and gas mixtures.

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.

Corrosion inside the compression chamber can reduce the pump
peformance and its lifetime. Therefore the chemical compatibility of the
process gases with the pump component materials should be checked.
In doubt, please contact your Busch representative.

Pump component materials with process gas contact:

–

ductile cast iron

–

polytetrafluoroethylene (PTFE)

–

fluoroelastomer (FKM/ FPM)

–

steel/ stainless steel

Solid particles must not get into the vacuum pump. Procedural errors
can result in the pump sucking in a certain quantity of liquid. If the
pump has sucked in liquid, a short drying time is necessary at the end
of the process.

The temperature of the drawn gas depends on the inlet pressure. The
lower the inlet pressure (Pa) is, the higher the temperature of the
drawn gas can be (TGas). Following values apply:

–

Pa < 50 mbar, TGas < 200°C

–

Pa > 50 mbar, TGas < 70°C

The vacuum pump is designed for use in an environment which is
non-explosive.

Max. permissible number of startings per hour: 6.

As far as temperature is concerned, the pump is suitable for continuous
duty at any inlet pressure between atmospheric pressure and ultimate
pressure.

Operating principle

The COBRA NS vacuum pumps are vacuum pumps with cooling water
and nitrogen circuits (optional).

The COBRA NS screw vacuum pumps work by the principle of screw
pumps. Two parallel screws (7) 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.

The COBRA NS screw vacuum pumps is driven by a water-cooled
motor.

The COBRA NS screw vacuum pumps can be combined with a Busch
booster pump, i.e. type WY 0500 C.

Cooling

The vacuum pump is cooled by

–

a cooling water circuit in the cylinder (4) (indirect cooling). A
temperature probe mounted in the cylinder of the pump regulates
a thermostatically controlled valve (TV). The water flow is
regulated by setting of the valve from position 0 (cold) to position
4 (warm). The setting depends on the vacuum application.
Use of a higher setting is recommended for the thermostatically
controlled valve to prevent re-sublimation or condensation inside
the pump.

CAUTION

Changing from position 0 to position 4 or vice versa must take place
in steps. The pump must stabilise after every change in setting.
Never switch directly from position 0 to position 4 or vice versa.

–

a cooling water circuit in the motor and in the drive housing (4)
(direct cooling). The cooling water flow is factory set on 2 l/min
and can be adjusted at the regulating valve CWR. This water circuit
is used to cool the motor and the oil.

–

filling of a cooling liquid (water-glycol mixture) in the water
chambers (6).

NOTE

: The NS 0070-0160 C vacuum pumps are always delivered

without oil, without cooling water and without cooling liquid.
Operation without these coolants can result in damage to the vacuum
pump.

Nitrogen system (option)

The nitrogen system performs two main functions

–

the nitrogen is used as dilution gas. The nitrogen flow is factory set
to 18 SLM and can be adjusted at the regulating valve DGR
according to the application. The nitrogen is injected into the
compression chamber. Dilution leads to an improvement in the
function of the screws particularly when drawing corrosive gases.

–

the nitrogen is used as sealing gas. The nitrogen is injected into the
intermediate chamber (5) to keep process gas out of the gearbox.

To set the nitrogen pressure of 1,5 bar recomended (max. 3 bar) at
the inlet, a manometer and a nitrogen regulating valve are necessary
to install on the vacuum pump.

Safety valve

The safety valve (SV) prevents excessively high pressure in the
expansion vessel (EV), relief pressure: 6 bar.

A silencer (SI) (optional accessory) at the exhaust reduces the noise
emission of the pump.

Product description

NS 0070-0160 C

Page 4

0870570353 (En)