Instruction manual

VHS-4, VHS-6 and VHS-250 Diffusion Pumps
13
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 (0.67 mbar).
Overtemperature Fit temperature sensors and pump fluid level
sensors with feedback to an interlock on the
heater power supply.
Insufficient water flow through 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” or larger in diameter.
Do not use hydrocarbon-based pumping oils.