text: The largest risk when using a separating funnel is that of pressure build-up. Pressure accumulates during mixing if a gas evolving reaction or physical change occurs. This problem can be easily handled by simply opening the stopper at the top of the funnel routinely while mixing. More standard procedure is to invert the separating funnel upside down, and open the stopcock to release the pressure, a step done repeatedly known as venting. This should be done with the tip of the funnel pointed away from the body.