Edwards EXT250 Series, Instruction Manual, Page: 17 / 42

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Technical data
B722-01-880 Issue K
2.5 Vent gas specification and vent control data
Although the pump may be vented to atmospheric air, high relative humidity of the air may greatly increase the
subsequent pumping time. To reduce pump-down times vent the pump with dry, clean gases.
Figure 3 - Maximum allowed rate of pressure rise during venting: system pressure
(Pa/mbar, with the backing pump isolated) against time (s), with the pump initially at full rotational speed
Table 5 - Vent gas data
Vent gas Dry air, nitrogen, argon or other inert gases
Maximum dew point at atmospheric pressure -22
o
C
Maximum size of particulates 1
μ
m
Maximum concentration of oil 0.1 parts per million
Maximum allowed rate of pressure rise See Figure 3