You're probably used to seeing rotary evaporators out in the open on a lab bench, or tucked away in a fume hood. Both options are acceptable, but will depend on various factors of the application and environment.
In this article, we explain the considerations to consider when deciding whether to use a fume hood with a rotary evaporator.
1. Health hazards of smoke
A rotary evaporator was used to remove volatile solvents. Although rotary evaporators are designed so that the evaporated solvent is condensed and collected, some volatiles may still escape. Some vapors may cause respiratory illness or explosion hazard if present in high enough concentrations.
Therefore, the evaporation process should always be carried out in a well-ventilated area. If there is insufficient ventilation, it is better to place the device under the hood.
Some procedures will involve the use of solvents that produce toxic vapors, in which case a fume hood should be used regardless of ventilation.
2. Explosion hazard
Certain applications increase the risk of explosion, including when using chemicals or mixtures that are explosive under certain conditions. For example, there have been numerous reports of azides in the presence of halogenated solvents causing explosions that shattered rotovap glassware.
In the event of an explosion, rotavapor operators and other bystanders are at risk of being hit by projectile glass shards and hazardous chemicals. Injuries from glass and chemical burns are common injuries associated with various laboratory explosions.
To reduce the risk of injury, the rotary evaporator can be used with the sash lowered in a fume hood. Lowering the sash of the fume hood was one of the precautionary recommendations made following a serious incident involving a rotary evaporator unit explosion. In this case, the researchers were using a rotary evaporator to remove organic solvents from azobenzene precipitates. The spinning flask exploded and blew shards of glass into her face, necessitating stitches.
3. Risk of implosion
There is also the risk of implosion, which is likely to happen if your glassware cracks or breaks before use. Once under vacuum pressure, defective glassware is prone to cracking, posing a risk of injury. You can use coated glassware to help reduce the risk of rotovap glass breakage, but a fume hood can also help.
If you choose to use a fume hood due to the risk of explosion or implosion, you will always want to keep the sash fully closed if desired. Some models have a removable control panel that can be used to operate the unit from outside the closed hood. For example, many Heidolph benchtop rotary evaporators have this capability.
4. Safety issues in high temperature applications
Your application may involve risks other than those described above. Let's say you're doing high temperature evaporation, which requires the use of an Oil Bath heated to over 100°C. This setup can present a safety hazard when running on an unattended bench.
By installing the equipment under a fume hood, the equipment will be free from interference and less likely to be disturbed and present a risk of injury.
5. Have the right equipment
This might sound obvious, but if your installation doesn't fit in a fume hood, you can't use it. Condensers are generally divided into two types: vertical and diagonal. The former is generally suitable for installations with limited work space, while the latter is more suitable for installations with limited high availability. If your fume hood is low enough to fit your stand condenser, you're probably out of luck.
Alternatives to Using a Fume Hood
In many cases, whether you don't have a fume hood in your lab, or you only have one, you can't use the fume hood for other applications. So what if you absolutely need more ventilation or better protection than your current setup? Well, there are two options:
buy case
The enclosure is a desirable alternative to a built-in fume hood to minimize exposure to fumes and vapors.
create the right environment
Depending on your application requirements, you may need to work in special environments. For example, some applications should be performed in a fully explosion-proof laboratory with minimum ventilation requirements.
In addition to the environment itself, it is important to consider any other equipment required, such as personal protective equipment (PPE).
in conclusion
The main reason for using a fume hood with a rotary evaporator is to better reduce the risks associated with inhaled fumes and to protect glassware from injury should it burst or explode. If your application requires these considerations, a fume hood should be strongly considered. Other options include purchasing a dedicated rotavapor enclosure or disposing of it in a special environment.
