Float Calculation
Abstract
On the fall semester of 2009, Non-linear Chemical Doser TM developed a Mathcad file to help operators to determine the float parameters given a non-linear doser lever arm. For our prototype, we calculated that our float needs to
weigh 4.95 lbs with a diameter of 6 inches and 4 inches of thickness.
Method
The float design parameters can be determined using a moment balance around the pivot of the lever arm. This is to ensure that a change in head in the entrance tank will cause a similar change in the relative height of the float. We first determined the weight and location of each components of the lever arm with respect to the pivot. We then identified all the moments for each of those components. We then specified a float diameter and specified and solve for the weight of the float with the specification that at equilibrium the float will be halfway submerged in the water.
Results/Discussion
The scale portion of the lever where the dual scale and the slider and the doser tube are connected is heavy enough that there will always be tension on the float. As water level in the entrance tank rises, buoyancy force will increase until the lever arm on the scale drops releasing the necessary alum flow rate while maintaining the tension on the float.
Conclusion and Future Work
We require a float with a weight of 4.95 lbs, diameter of 6 inches and 4 inches of thickness for our prototype lever arm.
Once we build the lever arm, we would further specify the float parameters by utilizing a makeshift float that we can adjus prior to ordering the final float for the design competition.
Bibliography
- CEE4540 Flow Control Measurement Notes at https://confluence.cornell.edu/display/cee4540/Syllabus
Deliverables
- Final Float Design Parameters and Calculations
- Float protype for March 2010 EPA Competition