Recommended Set-Up for Vacuum Filtrations
Every year we get 2 or 3 vacuum pumps in for repair. Complaints are: Don't work, Extremely noisy, Creates smoke in the air. In the majority of the cases, the problem was due to water or mist getting sucked into the pump. Every operator tells us this could not have possibly happened to them, but when we take the pump apart, we find a mixture of water and oil.
The way to avoid this is to use a "moisture trap" to protect the pump. The set-up illustrated below uses a second filtration flask as added protection to keep overflow and mist from reaching the pump.
The moisture trap is made by inserting a piece of glass tubing through a one-hole rubber stopper close to the bottom of the moisture trap.