Multiple 7401s On a Single Pump
3.
Change one valve to the pump-down position and note that the pressure in
the associated spectrometer begins to decrease after a few minutes of
pumping. It will take several minutes for the pressure to reach the 1000
µ
m
Hg read-out limit of standard Canberra Spectrometers. When the pressure
reaches about 100
µ
m Hg you will know that this channel and the pump-
down manifold are free of gross leaks. Turn the valve to the High-Vacuum
position and verify that the pressure on this side is in the same range.
4.
If the pressure on either side is not in the right range tighten and or re-
lubricate the vacuum line couplings.
5.
Repeat step 3 for each of the spectrometers in the system.
Routine Operation of the 7400-14
1.
Always evacuate chambers with the valve in the Pump-Down position.
2.
When the pressure in the chamber reaches the normal operating range turn
the valve to the High Vacuum position.
3.
Before opening a chamber turn the associated manifold valve to the pump-
down position.
4.
Before re-evacuating a chamber check to see that the associated manifold
valve is in the pump-down position.
Routine Precautions
1.
Never connect an evacuated chamber to a manifold or pump which is not
under vacuum. The chamber may draw oil vapor from the pumping system
and contaminate detectors.
2.
Service vacuum pumps periodically. Do not wait for them to fail. Consult
manufacturer’s instructions.
3.
Replace filters periodically. Oil clogged filters will reduce pumping speed
and may allow backstreaming.
7401/7401VR Alpha Spectrometer User’s Manual - 9231603C
15
