Page History

The first Stock Tank team goal is to obtain appropriate hydrometers for usage at plants. Ideally, the hydrometers will be made of polycarbonate or some other shatter-resistant material. Typical AguaClara PACl solution concentrations of 100-200 g/L require a device capable of reading between 1.0-1.2 SG and typical AguaClara chlorine solutions require a device capable of reading between 1.012-1.013 SG. Currently, the $74 Krackeler Scientific 1.000-1.220 polycarbonate hydrometer is being utilized to measure the density of PACl coagulant solution. The team is still researching devices for usage with chlorine; the $33.50 Cole Parmer 1.000-1.050 glass hydrometer with 0.0005 divisions is the tool currently used. Chlorine solutions pose an interesting challenge because they require a much smaller range than typical polycarbonate hydrometers for accurate measurement.

primary goal of the Fall 2013 team was to design a centrifugal pump to mix stock solutions, with test designs utilizing a rotating arm that employed the pressure gradient due to rotation to bring

dense solution located at the bottom of the tank to the top.

End-of-semester tests showed high pump inefficiency due to large amounts of wasted input power due to drag on the rotating arm

. The test results prompted entire mixing redesign by the Spring 2014 team.

Two main designs were fabricated and tested on the small scale: a shallow bucket with small holes in the bottom and a plate (each attached to a handle) that were pumped up and down in the stock tank. The bucket design was meant to physically bring dense solution located at the bottom of the tank to the top of the tank while the plate design created turbulence and jets to encourage mixing. Both designs achieved full mixing with the same number of pump cycles, but the plate design requires less time because when the plate reaches the surface height, it is immediately plunged back down to the bottom of the tank. The bucket design, meanwhile, requires waiting for the fluid to drain out before being plunged back to the bottom. Full-scale designs will be based on the plate mixer are will be restricted by stock tank dimensions.

Additionally, a water injection system was designed to deposit the necessary volume of water for the stock solution into the bottom of the tank. This process greatly reduced the amount of manual mixing required of the operator. Any required manual mixing is intended to be performed using the plate mixer described above.