A Simple Non-Contaminating Glass Pump During the process of saturating samples with an organic compound a pump which would circulate volatile organic solvents without introducing any contamination was required. The need for very low contamination levels (0.2 mg/100 ml of solvent) ruled out pumps with sealed hearings or plastic components, since the solvents used would extract grease or plasticizers. The flammable nature of these solvents also had to he considered. These objectives were achieved by the construction of a glass pump as shown in the figure. The impeller is a bar magnet totally encased in Pyrex tubing. The two tungsten wires to glass hearings were found necessary to prevent galling from glass to glass contact. Glass to Teflon or other inert material can be substituted for tungsten wire to glass hearings when liquids which are corrosive to tungsten are used. The impeller is rotated by a magnetic stirrer controller placed under the housing. The precision required in design and c o n s t ~ c t i o nis low. A cylindrical impeller with wall to impeller clearances of 5-Y4 in. produced a 12-in. head of heptane. In a free flowing system with a &in. head this pump circulated 150 l/hr. After several months operation we have not detected any deterioration in ei- - t e r n ther construction or performance of this pump.
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B. A. Baldwin F. W. Blanton Phillips Petroleum Company Bartlerville, Oklahoma 71001
Volume 50, Number 6, June 1973 / 437
