Rotary Evaporator Automation

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A critical step in the purification process is the removal of excess solvent to provide a pure product for chemical analysis and subsequent use. The rotary evaporator is a basic tool for removing excess solvent.

The AutoEvap is a new tool that extends the use of a standard rotary evaporator. AutoEvap is an addition to standard rotary evaporator systems that allows continuous drain of distillate as well as continuous feed of concentrate. Further considerations for this device were the need to gracefully recover from a sudden power loss such that it might start up in an undefined state during the power recovery in the lab.

By design the AutoEvap provides a pneumatic control and fiber optic sensor control that is intended to reach into large fire restraint solvent storage rooms such that solvents can be moved to and from large solvent drums to e.g. HPLC skids for purification and back to large solvent storage drums for stripped solvents. This way solvent use can be minimized by separating the solvent with a rotary evaporator and feeding it back into the HPLC skid.

Installation takes only a few minutes without tools. Once installed, the AutoEvap allows the evaporator system to run continuously in a safe unattended mode, feeding and removing solvent from the rotary evaporator at near constant vacuum (increasing efficiency). Drain and feed operations are controlled by the use of an embedded controller. The automated controller performs the operations listed below.

Operation Features
Initial liquid fill of evaporator flask
Liquid level detection to trigger refill of evaporator flask
Liquid level sensor triggers emptying solvent receiver bulb
Pneumatic emptying of receiver to distant container
Automated stop upon completion of evaporation process
Concentrate can be set to a specific liquid level thus avoiding over-concentration.

The AutoFill module connects to the standard stopcock on the rotary evaporator and places a fiber optic (Teflon, quartz) inside the boiling flask for liquid sensing. The sensor can be set at a specific level to stop concentration when the last of the feed concentrate has dropped to a certain level, preventing over-concentration.

The AutoDrain module replaces the receiver flask on any rotary evaporator. When the controller senses liquid in the receiver bulb, it triggers pneumatic drain of the solvent. A series of check valves maintain a constant vacuum in the evaporator at all times, and the evaporated solvent can be transported a significant distance to waste or recycling.

AutoEvap runs unattended
Easy retro-fit to any existing rotary evaporator
Teflon, glass and porcelain wetted surfaces
Empty receiver means no-reflux thus faster solute concentration
Safety shut-off that never overfill waste
Flexible use of supply and collection containers

Minimized foot print controller box can be mounted on existing rotary evaporator.
No modifications required to existing rotary evaporator
No tools to install or remove from rotary evaporator
Simple to switch from automated to non-automated original operation
Designed with the careful consideration of the needs for such equipment for corporate Environmental Health and Safety groups in mind



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  • Name:
    Abraham H Horstin
  • Type of entry:
  • Number of times previously entering contest:
  • Abraham H is inspired by:
    Working with others on their scientific and engineering needs.
  • Software used for this entry:
    AVR C programming
  • Patent status: