CAUTION:
Do not use the pump to pump gases containing more than 20% oxygen. This will cause the
lubricant to polymerise and the pump to fail prematurely.
Note:
Concentrations of gases may be modified by the compression of the pump.
The turbo pump is designed to pump the following residual gases normally used in high
vacuum systems:
•
Air
•
Carbon monoxide
•
Neon
•
Ethane
•
Methane
•
Nitrogen
•
Krypton
•
Argon
•
Propane
•
Carbon dioxide
•
Helium
•
Hydrogen
•
Butane
The pump can be used to pump oxygen and water vapour, subject to the following conditions:
•
Oxygen - When the pump is purged by an inert gas, oxygen can be pumped at
concentrations above 20% by volume. Refer to the nEXT85 instruction manual
(B8G0-00-880) for purge gas specification. However, if the pump is not purged, the
oxygen concentration must be less than 20% by volume.
•
Water vapour - Ensure that vapour does not condense inside the pump.
To pump a gas not in the list above, contact the supplier for advice. Failure to contact the
supplier may invalidate the warranty on the pump. The pump is not suitable for pumping
aggressive or corrosive gases.
Venting gas specification and vent control data
Although the pump may be vented to atmosphere, high relative humidity of the air may greatly
increase the subsequent pump down time. To reduce pump down times the pump should be
vented with dry, clean gases.
Refer to the nEXT85 turbo pump manual (B8G0-00-880) for the vent valve connection. Refer to
Vent valve screen
on page 20 for configuring the venting options.
Table 18 Vent gas specification and vent control
Vent gas specification and control
Reference data
Vent gas
Dry air, nitrogen, argon or other inert gases
Maximum dew point at atmospheric pressure -22 °C
Maximum size of particulates
1 μm
D395-94-880A - Technical Reference
Page 39