As you may know, rotary evaporator systems use vacuum to lower the boiling temperature of the solvent. However, using a vacuum increases the risk of glassware imploding.
In this article, we learn why rotavapor implosions occur, the dangers involved, and how to prevent rotavapor glassware from imploding and causing injury.
Why Rotary Evaporator Glassware Can Burst and Be Dangerous
Of course, the desirable effect of drawing a vacuum on your rotavapor unit is to reduce the pressure inside the system. However, the reduced pressure creates a suction effect inside the system components. This may cause the glassware to burst.
In addition to destroying the sample, implosion can cause projectile glass shards and liquid splashes. As you increase the vacuum and decrease the pressure, the risk of implosion increases. When glassware is damaged, the risk is multiplied.
How to Prevent Glassware Implosion and Better Reduce Risk of Injury
In addition to wearing appropriate personal protective equipment in any laboratory setting, you should also consider the following:
use the correct glassware
It is important to ensure that only glassware designed for use under vacuum is used. Other glassware may not be strong enough to withstand pressure changes.
Many rotary evaporators come with safety-coated glassware options to help prevent breakage. But keep in mind that this mostly applies to condensers and collection bottles. Evaporating flasks generally do not have a safety coating because they are required to withstand higher bath temperatures, which may deteriorate the plastisol coating.
For example, the FAQ section for the Hei-VAP Precision Rotary Evaporator explains which components to coat and why. For this product, only the condenser and collection bottle will be coated when you select the coated glassware set.
Carefully inspect glassware
Before using the rotavapor, all glassware should be carefully inspected and should not be used if it is visibly damaged. In addition to cracks, also look for scratches or chips. Note that it only takes a small crack to compromise the integrity of the glassware and cause it to break instantly under vacuum.
If your glassware does not have a safety coating, to better minimize the damage that could be caused if the glassware implodes, you can use tape. The criss-cross filament tape helps keep parts together in the event of an explosion or blast, meaning glass shards are less likely to injure lab personnel and damage nearby equipment. A grid or net is often applied to achieve a similar effect.
Slowly increase the vacuum
In addition to potentially causing sample collisions or foaming, applying too strong a vacuum too quickly can increase the risk of implosion. When desired, it should be increased gradually and only to the level required by the application.
use a fume hood
If you're concerned about implosion, consider using a rotary evaporator under a fume hood. Regardless, this may be necessary for some applications to avoid inhalation of toxic fumes.
If your main reason for using a fume hood is the risk of an explosion (or explosion), then you will most likely need to keep the sash closed and closed at all times. However, this makes it difficult to operate and control the rotavapor equipment. Fortunately, with some units, you can remove the control panel and operate the unit from outside the closed hood.
