Varian F1730308, Instruction Manual

Page: 37 / 49

2-1
SECTION II
OPERATION
During initial installation, the newly installed pump fluid may be subjected to a degassing process. This
may result in foreline pressure fluctuations and “bursts”. Such fluctuations are considered normal.
2-1 START-UP PROCEDURE
a. Evacuate the diffusion pump by means of the mechanical roughing pump to a pressure level
below 0.5 Torr (66.5 Pa). The diffusion pump will not function unless the discharge pressure is
less than the tolerable forepressure (approximately 0.5 Torr (66.5 Pa)).
b. Turn on the cooling water supply to the pump body and check that adequate flow is provided
by examining the amount of water discharged at the visual drain points.
WARNING
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The following conditions increase the risk of explosion:
• any air leaks into the system;
• roughing through a hot diffusion pump may cause some hot hydrocar-
bon fluids to ignite or explode when exposed to air;
• air release or admitting air to a pump with a hot boiler, permit a strong
oxidizer to contact the hot pump oil;
• high (above 1 micron (.133 Pa)) inlet pressure;
• insufficient (or low level of) pump fluid;
• running pump without cooling water circulating to main water cooling
coils;
• trapping water between closed isolation valves at inlet and discharge
of quick cool coils and running diffusion pump;
• foreign matter in the pumping fluid which changes its viscosity and
obstructs flow passages.
CAUTION
________
• Do not turn on the heater without fluid in the pump. This may ruin the
heaters and damage the pump.
• Do not air-release the pump while the boiler is hot. Most diffusion
pump fluids are heat-sensitive and will break down under these con-
ditions.
• Do not operate the pump without the foreline baffle. This may cause a
greater than normal fluid loss.
• Do not operate the pump for extended periods at an inlet pressure
above 1 micron (.133 Pa). High pressure operation may cause exces-
sive backstreaming.
• Do not operate the pump heater unless the cooling water is circulating.
It will cause the pump and fluid to overheat.