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).
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[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.
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[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.
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