Vacuum systems pose severe implosion hazards. Follow these guidelines and requirements to ensure system safety:
- Ensure that pumps have belt guards in place during operation.
- Ensure that service cords and switches are free from defects.
- Always use a trap on vacuum lines to prevent liquids from being drawn into the pump, house vacuum line, or water drain.
- Replace and properly dispose of vacuum pump oil that is contaminated with condensate. Used pump oil must be disposed as hazardous waste.
- Place a pan under pumps to catch oil drips.
- Do not operate pumps near containers of flammable chemicals.
- Do not place pumps in an enclosed, unventilated cabinet.
All vacuum equipment is subject to possible implosion. Conduct all vacuum operations behind a table shield or in a fume hood.
Do not underestimate the pressure differential across the walls of glassware that can be created by a water aspirator.
The glassware used with vacuum operations must meet the following requirements:
- Only heavy-walled round-bottomed glassware should be used for vacuum operations. The only exception to this rule is glassware specifically designed for vacuum operations, such as an Erlenmeyer filtration flask.
- Wrap exposed glass with tape to prevent flying glass if an implosion occurs.
- Carefully inspect vacuum glassware before and after each use. Discard any glass that is chipped, scratched, broken, or otherwise stressed.
Glass desiccators often have a slight vacuum due to contents cooling. When using desiccators, follow these guidelines:
- When possible, use molded plastic desiccators with high tensile strength.
- For glass desiccators, use a perforated metal desiccator guard.
A cold trap is a condensing device to prevent moisture contamination in a vacuum line. Guidelines for using a cold trap include:
- Locate the cold trap between the system and vacuum pump.
- Ensure that the cold trap is of sufficient size and cold enough to condense vapors present in the system.
- Check frequently for blockages in the cold trap.
- Use isopropanol/dry ice or ethanol/dry ice instead of acetone/dry ice to create a cold trap. Isopropanol and ethanol are cheaper, less toxic, and less prone to foam.
- Do not use dry ice or liquefied gas refrigerant bath as a closed system. These can create uncontrolled and dangerously high pressures.
A disinfectant trap should be used in-line when a vacuum is used with hazardous biological materials. The diagram below illustrates a suitable disinfectant trap assembly.
Disinfectant Trap System
END OF SECTION
Reviewed November 2014