Rotary evaporator bumping: a troubleshooting sequence

Bumping is a process behavior, not automatically a failed component. A structured check makes it easier to separate a pressure-control issue from a loading or heat-transfer issue.

A repeatable sequence

1. Confirm the flask is not overloaded for the current rotation and bath conditions.
2. Check whether pressure is changing too quickly for the material.
3. Verify that the flask is rotating smoothly and that the vapor path is clear.
4. Check condenser temperature and receiver conditions.

Change one variable at a time

Small changes produce better evidence than multiple simultaneous adjustments. Record the pressure, bath temperature, rotation, and visible behavior so the next run starts with useful information.