Edwards EXT250 Series, Инструкция по эксплуатации, Страница: 11 / 42

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Introduction
B722-01-880 Issue K
1.3 Vent options and vent control
To maintain the cleanliness of your vacuum system, we recommend that, whenever you switch the pump off, you
vent the pump (or vacuum system) when the speed of the EXT pump is between full rotational speed and 50% of full
rotational speed. At and above 50% of full rotational speed, the rotor spins fast enough to suppress any backstreaming
of hydrocarbon oil from your backing pump.
However, if you vent the pump when it is at full rotational speed and the rate of pressure rise is too high, the pump
life may be reduced. We therefore recommend that you either limit the rate of pressure rise in accordance with
Figure 3 , or only open the vent-valve after the EXT pump speed has fallen to 50% of full rotational speed.
The rate of pressure rise cannot be controlled by the manual vent-valve, so if you use the manual vent-valve, you
must only open the vent-valve after the EXT pump speed has fallen to 50% of full rotational speed.
If you use a TAV5 vent-valve, but you cannot limit the rate of pressure rise, you must only open the vent-valve after
the EXT pump speed has fallen to 50% of full rotational speed. If you use the EXC Controller to control your TAV5
vent-valve, configure the Controller to select this option: refer to
Section 3.4 for more information. The
EXC Controller is factory set to vent when the EXT pump is at 50% of full rotational speed after you have selected
Stop.