A Simple Apparatus for Stirring Solutions Contained in Submerged, Sealed Vessels John H. Grinstead, Jr., and Jack M. Sullivan Chemlcal Research, Tennessee Valley Authorlty, National Fertilizer Development Center, Muscle Shoals, AL 35660 Solubility studies conducted in our laboratory1 required that a series of solutions contained in sealed vessels be stirred while partially submerged in a controlled-temperature bath. An apparatus which can simultaneously stir the contents of several submerged flasks is not commercially available. Therefore, we designed and constructed a simple apparatus to accomplish this task from readily available materials. The stirring units consist of four Cole-Parmer model 7018 Masterflex polyphenylene sulfide pump heads (other brands could be substituted; use of trademarks or brand names does not constitute a TVA endorsement), which were disassembled and mounted on a semicircular. 6-in. radius. %&.-thick aluminum plate using 1%X %in. bolts and winbuts. The shaft and bottom d a t e of the oumo . . heads were inserted through the bearings in the housing and through 18-ln. holes drilled in the aluminum olate. Reducina unions were used to connect 5/16-in.-o.d., three-prong micro~lamps,with the extension rods trimmed to 11/~ in., to the top of the pump head shafts; 3-in.-long Teflon-coated magnetic stirring bars were placed in each clamp. The drive mechanism for the stirrers consists of a variable-speed laboratorystirrer, with a Y ~ i nshaft . connected to a central sorocket that is 3%in. in diameter and has 60 teeth. A 2%-in.-diameter, 37-too& sprocket with a ?!,&.-high collar was olaced on each .oumo . head shaft. which extended below the aluminum plate and was secured by a set screw in the sorocket collar. The central 60-tooth drive sorocket was coupied to the four smaller sprockets with a chain. Two 14-in.-long, %-in.-0.d. aluminum rods were clamped parallel to each other approximately 6 in. apart and mounted at a 90' anele to a heavv-base ring stand. The drive assembly was mounted to the stirring assembly via a %-in. aluminum rod mounted to the top of the aluminum plate, which was clamped to the two rods extending from the ring stand. The stirrer motor then was clamped to the ring stand. The chain tension was adiusted bv chaneine the leneth of the drive shaft or the position of t i e stirrer gotor. F&I 50mL high-temperature plastic Erlenmeyer flasks were mounted with four three-prong microclamps, which were clamped onto the top 14-in. rod mounted to the ring stand. Magnetic coupling between the sprocket-driven 3-in. bar magnets and magnetic stirring bars placed in the Erlenmeyer flasks resulted in simultaneous stirring of each solution. The unit used in our solubility studies, including the oil bath 'Sullivan. J. M.; Kohler, J. J.; Data l988,33,367-370.
vessel, heater-regulator hich-temperature plastic Erlenmever flasks, and a ihermomeier, is shown in ;he figure. Many variations of this design are possible using materials on hand in a particular labo~atory.For example, cheaper bearings with mounting brackets, along with %-in. aluminum rod stock for the shafts, could be substituted for the pump head parts. Our cost for the stirring units was essentially zero since the parts were available in the laboratory. The most expensive part would be the pump beads, which retail for approximately $62 each.
Grinstead, J. H.. Jr. J. Chem. Eng. Stirring apparatus wilh bath equipment
Volume 67 Number 6 June 1990
521
