Gas bubbler

A gas bubbler is a piece of laboratory glassware which consists of a glass bulb filled with a small amount of fluid—usually mineral or silicone oil, less commonly mercury.

In the latter case, an oil bubbler is usually installed at the end of the inert gas manifold on a Schlenk line to prevent contamination by atmospheric oxygen and water.

A gas bubbler acts as a one-way valve—gases (hot air, evolved gases, solvent vapors) from the inlet will bubble through the fluid before being vented to the atmosphere.

If there were an underpressure in the reaction vessel (such as when heat is removed, and the gases within contract), some fluid is sucked into a sump to equalize the pressure, instead of air.

They usually have a longer body to prevent mercury from splashing out through the bubbler outlet, and the inlet connection usually has a sintered glass disc to prevent mercury from being sucked back into the inert gas system when refilling an evacuated vessel.