Varian HS-20, Instruction Manual, Page: 7 / 43

iii
THE INSTALLATION, OPERATION, AND/OR SERVICING OR DIFFUSION PUMPS INVOLVES ONE
OR MORE OF THE FOLLOWING HAZARDS, ANY ONE OF WHICH, IN THE ABSENCE OF SAFE
OPERATING PRACTICES AND PRECAUTIONS, COULD POTENTIALLY RESULT IN DEATH OR
SERIOUS HARM TO PERSONNEL.
Hazard Suggested Corrective Action
Loss of utility: water and/or electricity Provide sufficient backup water and power supply as neces-
sary to effect a safe shutdown under worst case conditions.
Overpressure in foreline Provide an interlock to ensure that the power supply to the
pump heater cannot be activated if the foreline pump is not run-
ning AND/OR pressure in foreline is above 0.5 Torr (66.5 Pa).
Overtemperature Fit temperature sensors and pump fluid level sensors with
feedback to an interlock on the heater power supply.
Insufficient water flow through the Use water flow sensor and feedback to interlock the heater
maincooling coils power supply.
Water trapped between inlet and Provide vent or pressure relief valves for both quick-cool coil
outlet of quick-cool coil,or liquid and liquid nitrogen trap.
nitrogen trapped between inlet and
outlet of liquid nitrogen trap
Loss of ground integrity Incorporate ground fault interrupt circuit into heater power
supply.
Positive pressure in pumping system Integrate pressure relief valve in vacuum system.
High voltage Prevent personnel contact with high voltages; design and
attach warnings.
Toxicity/Corrosivity Toxic and/or corrosive gases must be vented to a safe loca-
tion, ensuring adequate dilution or scrubbing to safe levels,
taking all action required to meet air quality standards.
Explosion Integrate pressure relief valves in all systems using pumps
10 inches or larger in diameter.
Do not use or recommend the use of hydrocarbon-based
pumping oils.