The baffle should not fully extend to the bottom of the tank and a noticeable gap, usually 1/2 to 1-inch in size, should be left between the baffles and the tank walls if solids are present or for viscosities over 500 cPs to prevent a buildup where the baffle connects to the tank wall. It is suggested that four baffles be used in this situation with them placed 90 degrees apart on the walls of the container and sized approximately 1/12th of the tank’s diameter. When this occurs, the mixing action in the tank will be poor. In this configuration, it is recommended that the operator put baffles on the walls of the tank in order to prevent the contents of the tank from turning in the direction of the mix, or creating an inefficient vortex. Vortexing occurs when the contents of the tank swirl around the walls of the tank without much top-to-bottom turnover this creates a less-efficient mixing operation and the possibility of uneven mixing or blending.Ĭylindrical tanks with capacities of more than 1,000 gallons may require that the mixer be mounted directly in the center of the tank with the shaft in a vertical orientation. On-center angling is better for gentler mixing and creates a vortex. Angling the mixer 15 to 20 degrees off of the tank’s centerline is preferred when good material turnover is required, as when mixing a slurry. Effective mixing patterns will be achieved if the mixer is angled 10 to 15 degrees away from the vertical, either off-center or on-center. In most mixing applications involving small cylindrical tanks of 1,000 gallons or less, the mixer is clamped to the side of the container. With that in mind, the position of the shaft and prop in the mixing container is a critical concern. The goal of any portable mixer is to either blend, dissolve or disperse, and to do this in the most efficient manner. This is because a mixer with dual props of the same diameter has a higher head capacity and will produce an increase of flow of around 20 % (dependent on propeller spacing), but will require an 80 % increase in power to create that increased flow. Keep in mind, though, that when determining mixing rate that dual props do not produce twice the flow of single props. In this case, the props should be located at least two prop diameters apart and the upper prop should be submerged at least two prop diameters below the fluid surface to ensure good mixing. In general, dual props will also be required in any container whose height is greater than 1.5 times its diameter. This configuration can produce the vortex that is required to draw in powder or liquid materials, even in a baffled tank. In this case, one prop is placed at the top of the shaft, near the surface of the liquid, while the second is located in its traditional position at the bottom of the shaft. Since it may be difficult to create a vortex in a baffled tank, a solution can be to use dual props. Another consideration in the realm of vortexing may be the need to use two props on the shaft.
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