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Best Practices for Rotary Evaporator Maintenance

By Aimee O'Driscoll, 21 February 2020

A rotary evaporator can be a big investment, but it’s also an imperative piece of equipment for many applications. Maintaining your rotary evaporator properly can help ensure it performs efficiently and increase the lifespan of your unit.

Best practices for maintaining your rotovap include:

  1. Cleaning your unit properly
  2. Not leaving water in your bath
  3. Checking glassware for damage
  4. Not setting the speed too high
  5. Changing parts as needed

In this post, we take a look at each of these more closely.

1. Clean Your Unit Properly

To keep your rotary evaporator in top working order, and avoid cross-contamination between samples, your equipment needs to be cleaned properly.

Some favor the “quick and dirty” method of cleaning, which involves pulling vacuum to flush glassware with acetone. However, this method could damage your pump, so you’re better off performing a thorough cleaning. This involves taking apart the equipment, washing parts separately, and allowing them to dry before reassembling. If your application calls for it, you may also choose to sterilize some parts in an autoclave.

The condenser can be a bit tougher to clean than other glassware. In particular, you may see some algae buildup that needs to be removed. One option is to soak the condenser in an agent such as nitric acid or hydrochloric acid for a few hours before rinsing. Remember to use proper protocol including wearing appropriate personal protective equipment when working with these materials.

2. Avoid Leaving Water in Your Bath

It may seem convenient to simply leave the same water in your rotovap water bath for days or even weeks. After all, it’s not coming in contact with your sample, so it seems harmless enough.

However, leaving water in the bath can lead to fouling due to dust, debris, and inevitable algae growth. It can also cause rust, resulting in irreparable damage, especially if the bath has an exposed heating element.

If you’re using oil in your bath, you can get away with changing it less frequently, but it should still be cleaned out regularly. If the oil has been overheated at any point, it should not be reused.

3. Check Glassware Regularly for Damage

Damaged glassware is prone to breaking easily when you pull vacuum. Even a small scratch or chip can result in implosion. It’s important to check all your glassware before use.

Using safety coated glassware can help minimize the potential damage if there is an implosion. If that’s not an option, using filament tape in a crisscross pattern (or mesh or netting) will help keep the broken pieces together, lowering the risk of shards hurting someone.

 

Taped glassware.

A rotovap setup with a taped collection flask.

4. Don’t Set the Speed Too High

It can be tempting to simply set the speed as high as possible. It makes sense that a faster speed will result in a more efficient process, and this is the case to some extent. However, using your rotovap at too high a speed can cause problems with the equipment, including deterioration due to vibrations and mechanical issues.

In addition, above a certain speed (found to be between 250 - 280 rpm), turbulence will start to decrease, lowering the rate of evaporation.

5. Change Seals As Needed

Although your rotovap should last you a long time, it’s inevitable that certain parts will need replacing from time to time. Sealing rings, in particular, will likely need to be replaced fairly regularly (roughly once per year for normal usage).

Cleaning seals when you clean your glassware can help prolong their life, but they can still become damaged, especially if used with incompatible materials. You can check your seal for visual damage, but a tell-tale sign that you may have a problem is if you have difficulty reaching the desired vacuum. 

It’s recommended you consult your equipment manual for specific details on changing seals.