Varian VHS-250, Инструкция по эксплуатации

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2-1
VHS-4, VHS-6 and VHS-250 Diffusion Pumps
D
R
A
FT 2/
24
/05
Section 2. Operation
CAUTION
❑
Before turning on the heater, ensure there is fluid in the pump.
Running the heater without fluid can ruin the heater and
damage the pump.
❑
Do not air-release the pump while the boiler is hot. Most
diffusion pump fluids are heat sensitive and breaks down under
these conditions.
❑
Do not operate the pump without the internal splash baffle or
foreline baffle in place. If the splash baffle is omitted, the pump
may be unstable and operate at a low speed. If the foreline
baffle is omitted, there may be excessive fluid loss.
❑
Do not operate the pump for extended periods at inlet pressures
above 1 mTorr (1.3x10
-3
mbars). High-pressure operation can
cause excessive backstreaming.
❑
Do not operate the pump heater unless cooling water is
circulating. It causes the pump fluid to overheat.
2.1 Startup
During initial operation of the diffusion pump, a fresh charge of diffusion pump oil may go
through a degassing process. This can result in inlet and foreline pressure fluctuations.
These pressure fluctuations are normal.
1. Visually inspect the sight glass assembly to ensure that the diffusion pump has been
charged with the proper amount of diffusion pump fluid.
When properly filled, the oil level (when the pump is cold) is even with the FULL/COLD
mark on the oil level indicator.
2. Evacuate the diffusion pump (rough pump) with a mechanical backing pump
(customer supplied).
The pressure must be reduced to less than 0.5 Torr (.66 mbars). The backing pump
should remain connected to the foreline of the diffusion pump.
3. Turn on the cooling water supply to the pump body and verify that the cooling water is
not being supplied to the Quick Cool Coil at this time.
4. Turn on the power to the diffusion pump heater.