Hello All,
From my experience with this equipment, I can rationalize a few motives for manual manipulation of the pressure. I'd be interested to hear everyone's thoughts from a safety perspective on how this could be improved:
- Manually manipulating the stopcock to achieve adequate pressure is done to prevent "bumping."
- Lowering the pressure beyond textbook level is done to achieve rapid evaporation for sometimes sensitive materials, or time-dependent operations.
Further, I have a question regarding the incident report:
- Was the stopcock leading to the vacuum tubing closed between use periods -- essentially while ether was lying dormant in the collection bulb of the rotary evaporator?
If it was open to vacuum, I could easily see ether buildup in the vacuum/vacuum line adding to the UEL. I believe ensuring that stopcocks are closed to create a sealed system for the rotovap while not in use would be a great precaution not discussed in the paper. In theory, this would minimize entrainment into the cabinet during standby operation. Additionally, it does not need to be opened until the vacuum is actively engaged and functional via the switch mentioned that controls both vacuum and fan.
In general, an interesting analysis. Next step is the hard part, convincing the organic labs why they should follow these controls when this sort of operation has been performed this way for easily 100 years!
Kind regards,
Christopher E. Sleet, Ph.D.
Safety Specialist - Chemical Safety
Office of Safety and Business Continuity
The University of Texas Southwestern Medical Center
