Modified Atmosphere Gas Flows

Potential issues and solutions

Breaking a pipette tip during degassing

If the purge pipette is inserted too far into the reaction flask, it may be broken by the spinning stirrer bar. Broken glass inside your reaction flask should not affect the reaction. However, the pipette should be replaced to ensure effective degassing of your solvent.

Blocked Pipette tip

Pipettes can occasionally become blocked with solids from the reaction mixture. Nitrogen flow through a blocked pipette should be stopped immediately, and any pressure build-up alleviated by removing the nitrogen supply tube from the pipette. If pressure is allowed to build up inside the pipette, it could cause the glass to shatter. Solvent degassing can continue once the blocked pipette has been replaced. 

Loss of oil from the bubbler

If the flow of nitrogen through an oil bubbler is too fast, oil may be expelled from it.  In this case reduce the nitrogen flow to an appropriate rate (see GIF) and top up the oil in the bubbler as necessary. It is important that there is sufficient oil in the bubbler to form a seal in the glass bubbler to prevent air from entering the reaction system.