When using a vacuum source, it is important to place a trap between the experimental apparatus and the vacuum source. The vacuum trap
- protects the pump and the piping from the potentially damaging effects of the material
- protects people who must work on the vacuum lines or system, and
- prevents vapors and related odors from being emitted back into the laboratory or system exhaust.
There have been incidents at UC San Diego where improper trapping caused serious failure of building vacuum pumps and in one case in 2009 the explosion was so severe that the pump was completely destroyed leaving the vacuum system in disrepair for months. Luckily no one was injured.
Proper Trapping Techniques
To prevent contamination, all lines leading from experimental apparatus to the vacuum source should be equipped with filtration or other trapping as appropriate.
- For particulates, use filtration capable of efficiently trapping the particles in the size range being generated
- For most aqueous or non-volatile liquids, a filter flask at room temperature is adequate to prevent liquids from getting to the vacuum source.
- For solvents and other volatile liquids, use a cold trap of sufficient size and cold enough to condense vapors generated, followed by a filter flask capable of collecting fluid that could be aspirated out of the cold trap.
- For highly reactive, corrosive or toxic gases, use a sorbent canister or scrubbing device capable of trapping the gas.
For most volatile liquids, a cold trap using a slush of dry ice and either isopropanol or ethanol is sufficient (to -78 deg. C). Avoid using acetone. Ethanol and isopropanol
are cheaper and less likely to foam.
Liquid nitrogen may only be used with sealed or evacuated equipment, and then only with extreme caution. If the system is opened while the cooling bath is still in contact
with the trap, oxygen may condense from the atmosphere and react vigorously with any organic material present.
Requirement: Use the Chemical Hazard Use Application, or CHUA, to create hazard control plans* (HCPs) for work with high hazard chemicals.
* At UC San Diego, a hazard control plan is a standard operating procedure (SOP).
Follow basic emergency preparedness best practices:
- Never work alone when hazardous chemicals are involved.
- Prepare for spills.
- Clean up only very small quantities and only if you have been properly trained. All other spills should be cleaned up by specially trained personnel.
- Read How to Handle Chemical Spills in Laboratories.
- Keep a fully stocked chemical spill kit easily accessible.
- Train personnel on how to use the spill kit, and when it is safe to do so.
- Know the locations of emergency equipment and how to use it:
Emergency override buttons (EOBs)
Some laboratories have emergency override buttons (see image at right) installed to provide maximum room ventilation in the event of a chemical emergency that impacts laboratory air.
Activate this button only if you feel laboratory air has been impacted by a chemical emergency.
- Open the clear cover and push where it says PUSH HERE. Once activated, room air supply and exhaust will be ramped up to maximum capacity to ventilate the space.
- Evacuate all personnel from the space immediately. Stay out until the room is cleared for reentry.
When the button is pushed, UCSD Police and Environment, Health & Safety (EH&S) will be contacted to investigate. To ensure rapid response:
- Contact UCSD Police after activating the EOB: Call 9-1-1 from campus phones.
- Provide the police with any useful information.
When the issue has been resolved, the EOB will be deactivated by authorized personnel and the space will be declared safe for reentry.
First aid kits and Emergency Guides
First aid kits (PDF) and Emergency Guides are provided by EH&S in work areas using hazardous materials or generating hazardous waste.
- The department representative, typically your Area Safety Coordinator, is responsible for monitoring first aid supplies and expiration dates.
- Contact EH&S, (858) 534-3660, if they are missing, damaged, or to request replacement supplies for EH&S-provided first aid kits.