Vacuum systems include those activities involving mechanical vacuum pumps, building vacuum systems, water aspirators, or steam aspirators. 

Work with vacuum systems poses a substantial danger of injury to the operator from flying glass shrapnel released during an implosion. Other hazards may include: 

  • The toxicity of the chemicals in the vacuum system 
  • Fire following breakage of a flask containing flammable solvents 
  • Toxicity from the mercury in manometers and gauges 
  • Over- or under-pressurization arising with thermal conductivity gauges 
  • Electric shock with hot cathode ionization systems. 

Operational Practices

[collapsed title=Vacuum Apparatus]

  • Vessels used in vacuum operations shall be protected with suitable relief valves (vacuum breaker). 
  • A protective shield shall be placed around evacuated systems. 
  • “Fish net” or electrical tape shall be wrapped around all glassware under reduced pressure.
  • PPE for laboratorians shall include safety glasses or goggles AND  face shields when working with evacuated systems or setting up such systems. 
  • The vacuum system shall be been arranged to allow the equipment to be moved without transmitting strain to the neck of the flask; flasks are to be supported from below as well as by their necks. 
  • The vacuum apparatus must be well out of the way of traffic to avoid being struck inadvertently. 
  • Belt-driven mechanical pumps shall be equipped with protective guards to enclose the moving belts (machine guarding). 

[/collapse]

[collapsed title=Capture of Contaminants]

  • Each vacuum system used for solvent distillation operations shall be  protected by a suitable trapping device (cold trap, filter, liquid trap) with a backflow check valve. 
  • Water, solvents, and corrosive gases shall be trapped and not allowed to be drawn into the building vacuum (house) system. 
  • When mechanical vacuum pumps are used with volatile substances, the input line to the pump shall be fitted with a cold trap to minimize the amount of volatile materials entering the pump and dissolving in the oil. 
  • Use pump oil that is appropriate for the contaminant such as Fomblin® when working with corrosives or other materials that are not compatible with hydrocarbon based oils.
  • If particulates could contaminate a vacuum line (e.g., from an inert atmosphere dry box or glove box), a HEPA filter shall be installed. 
  • If pump oil becomes contaminated, it shall be drained and changed to prevent the exhaust of chemicals into room air. 
  • Used pump oil shall be labeled Used Oil and disposed of through GT EHS. 
  • Records of pump use shall be maintained for general-purpose lab pumps in order to forestall cross-contamination or reactive chemical incompatibility problems.
  • The exhaust from evacuation of volatile, toxic, or corrosive materials shall be vented to an air exhaust system such as a chemical fume hood or local exhaust duct. 

[/collapse]

[collapsed title=Vessels]

  • Glass vessels used in conjunction with the vacuum system should be checked with polarized light for cracks, scratches, or etching each time the vessel is used. At minimum, a visual inspection will be conducted. 
  • Dewar flasks shall be wrapped with tape or enclosed in wooden or metal containers. 
  • Reduced pressure must never applied to flat-bottomed flasks unless they have been designed for this purpose. 
  • Vacuum desiccators shall be made of borosilicate/Pyrex glass or plastic. 
  • Evacuated dessicators must never be carried or moved. 
  • Dessicators shall not be opened until atmospheric pressure has been restored. 
  • If rotary evaporators are used, increases in rotation speed and application of vacuum to the flask are gradual.

[/collapse]