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Schlenk Line Diagram (Vacuum/Inert Gas, Bubbler, Cold Trap, Labeled)
A Schlenk line handles air- and moisture-sensitive reagents. Taps switch each port between a vacuum manifold and an inert-gas (nitrogen or argon) manifold, so the inside of a flask can be replaced with inert gas.
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Equipment
- Schlenk line (dual vacuum / inert-gas manifold)
- Nitrogen cylinder and regulator
- Oil bubbler
- Cold trap (liquid nitrogen)
- Vacuum pump
- Schlenk flask
- Septum and syringe
- Dry-ice bath (−78 °C) and magnetic stirrer
Setup tips
- Replace the air in a flask by evacuating and back-filling with inert gas about three times.
- Connect an oil bubbler to the inert-gas outlet to see the flow, and to stop air from flowing back in.
- Keep the regulator outlet pressure low (around 0.05 MPa gauge). The actual line pressure is set by the depth of oil in the bubbler; too high a supply can pop joints and septa if the line is blocked.
- Cool the cold trap with liquid nitrogen only after the system is under vacuum. Cooling it while open to air condenses liquid oxygen, which can explode with organic material.
- To shut down, remove the liquid-nitrogen dewar from the trap before letting the system back to atmospheric pressure (never admit air to a cold trap).
- Add reagents by syringe through a septum under a flow of inert gas.
Common mistakes
- Cooling the trap with liquid nitrogen while it is open to air (liquid oxygen).
- Running inert gas without a bubbler (pressure builds; air flows back).
- Setting the regulator outlet pressure too high.
- Doing only one evacuate–refill cycle.
Always follow your institution's safety rules and your supervisor's instructions.
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