Agilent Technologies VHS-4, Instruction Manual

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ix
VHS-4 Diffusion Pump
DRAFT 8/7/02
Diffusion Pump Hazards
Designers of systems utilizing diffusion pumps must design out hazards wherever possible. For hazards that cannot be
designed out, warnings, procedures, and instructions on proper use and servicing are provided. Please use guards, safety
features, and interlocks as recommended.
Refer to Table 1 for a list of general hazards and recommended actions, Table 2 on page x for a list of prohibited actions
that can result in explosions, and Table 3 on page xi for a list of pressurization hazards that can result in damage to
equipment.
THE INSTALLATION, OPERATION, AND SERVICING OF 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.
Table 1 General Hazards
Hazard Suggested Corrective Action
Loss of utility: water and/or electricity Provide sufficient backup water and power supply as
necessary 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
running and/or the pressure in foreline is above 0.5 Torr
(0.38 mbar)
Overtemperature Fit temperature sensors and pump fluid level sensors with
feedback to an interlock on the heater power supply
Insufficient water flow through the main cooling coils Use water flow sensor and feedback to interlock the heater
power supply
Water trapped between inlet and outlet of Quick Cool coil,
or liquid nitrogen trapped between inlet and outlet of
liquid nitrogen trap Provide vent or pressure relief valves for both Quick Cool
coil and liquid nitrogen trap
Loss of electrical 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 and Corrosivity Toxic and/or corrosive gases must be vented to a safe
location, 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 hydrocarbon-based pumping oils