Tuesday, August 19, 2008

There was a time when people found it impossible to imagine a vacuum. How could there be a place where there is nothing? After the Michelson/Morley experiment in 1887 failed to find the Luminiferous Aether the earth was supposed to be traveling through, the possibility of a vacuum in space began to be accepted. Actually Muslim scientists were discussing the possibility of creating a vacuum around the turn of the first century. By the 17th century European water pump design was good enough to produce a measurable vacuum. A perfect vacuum is unachievable in the laboratory and does not exist in space. There are many uses for vacuums, however imperfect, in the laboratory. Vacuum ovens by Sheldon and Thermo are used to dry samples, or remove volatile solvents from samples. Filtering flasks, Buchner funnels and filter funnels are used to filter samples. Buchi Rotary evaporators, Labconco vacuum concentrators, Eppendorf centrifugal concentrators, and Labconco freeze dry systems are all used for removing volatiles from samples. For a small vacuum environment Nalge Nunc makes vacuum chambers and vacuum desiccators as does Bel-Art. A vacuum may be created in a number of ways, the obvious of which is a vacuum pump. Some vacuum pumps are simple for mostly dry samples such as the Gast pumps. Some are designed for specific purposes such as handling volatile organics like the Gardner Denver Welch and BrandTech pumps. A vacuum can be created by aspiration, Nalge Nunc and Troemner Henry make such devices. Nalgene also makes a hand pump for creating a vacuum for a small volume. To carry the vacuum to the apparatus, vacuum tubing and valves are necessary. Vacuum grease is used to maintain a vacuum seal. Remember, there is a place for nothing.