Bart Explains how to find and prevent leaks in rotary evaporators…

I was out riding my bike last week, and after a short while, I was getting out of breath; This was nothing new for me, but the effort required to keep up the pace I had set, which admittedly wasn’t the fastest, seemed to have increased. I struggled on for a while until, finally, the thought occurred – perhaps the problem wasn’t me! I realized that my rear tire had lost pressure due to a leak. I made a quick repair, got the tire back to pressure, and within no time, I set off again and quickly got back to speed. All of this got me thinking about other problematic leaks, specifically leaks within a rotary evaporator.

Over the years, I have talked in length about rotavapors in this blog, from achieving optimal pressure and temperature to configuring them. Today though, I would like to speak specifically about leaks as they can slow down your process and significantly reduce efficiency, much like my leaky tire.

Leaks can cause havoc in a rotary evaporation system. The instrument will not reach set vacuum levels and, as a result, will continue pumping, trying to achieve the set level. This will ultimately reduce the pump’s lifetime and increase power consumption. So how do you know if your rotavapor has a leak? There are a few tell-tale signs that will alert you to the problem. The most apparent indicator might be a noticeable smell, as vapor can escape through the pump. Sometimes you can listen for leaks by placing your ear next to the various connections. You may also notice that your process is taking longer and is less efficient. The best way, however, is to perform a leak test. For this, the rotavapor is evacuated to 50mbar, and the pressure increase is monitored for one minute with the vacuum pump stopped. For some rotary evaporators, an automatic leak test is available through the maintenance menu. A leak test will help you pinpoint the source of the leak and acquire meaningful data to ensure your fix has remedied the problem.

If an initial leak test gives you a high leak rate (>5mbar/min), you can start excluding parts of your rotavapor system to pinpoint the source of the leak. Rerun the leak test, and when a result is considerably lower than the initial leak rate, you have found the source of your leak!

Start by excluding the vacuum pump from the system by kinking the connecting hose during the leak test when the vacuum is reached. If the vacuum pump is the source of the leak, check all tubes and seals and replace any damaged or worn parts.

Fixing a leaking rotavapor is easy, as in most cases, the source of the leak is one of the following:

• Hoses are not tight
• Seals are worn out

For the seals, I recommend first checking the ones that are easily accessible, which are the ones on the hose connections. Seldom is the source of the leak the main vacuum seal. Therefore, check this one at the end.

Following my suggestions, you should have your rotavapor running smoothly and efficiently and increase your instrument’s lifespan. Ensuring no leaks also has the benefit of protecting the environment as well as your health. For further tips on enhancing the performance of your rotavapor, check out my previous blog on Eco-Friendly rotary evaporation and save up to 45% energy with my handy tips. If you’re looking for general advice on how to save time during rotary evaporation, take advantage of this great poster available for free. And with this, you should have a squeaky, not leaky, clean performance of your distillations!

Till next time,