Talk:Aquarium pump

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We received your report, and you have some interesting results. Typically we expect to see your primary findings and conclusions in the executive summary, rather than needing to dig for them. Detailed comments follow:

  • Please include a picture of the product
  • Be sure to consider issues of cleaning and storage in addition to use. Also, the siphon appears to be used both to remove water from the tank and to clean gravel at the bottom of the tank. Are these two uses distinct?
  • You might consider alternative uses for the siphon, such as emptying a waterbed or hot tub.
  • Product function descriptions are relatively clear, but a figure would help. Additionally, some explanation of the physics of how a siphon functions would be helpful. The videos are interesting, but some explanation of what we are supposed to be looking at in each is in order.
  • FMEA: We are surprised that hole or wear in the tube would be more likely than blockage. It seems that tube blockage is a quite likely failure mode that could be difficult to correct if the right (wrong) sided rock were to become jammed.
  • DFE – your analysis is sensible, and we agree that there are likely not significant impacts associated with this product.
  • For the bilge pump, it is not clear how the flapper attaches to the rest of the device. Also, was the plunger valve removed from the rest of the assembly? How is this assembled?
  • The DFMA analysis is a good overview with some good ideas.
  • For the fluid analysis of the bilge pump, the weight of the water lifted by the person is 1.23 lbs, but the applied force must be greater because of 1) friction forces between the piston and the sleeve, and 2) the damping force created by water moving around the seal when the piston is pressed down. Do you have intuition for which of these forces dominate and what the total applied load would be?
  • For the fluid analysis of the siphon, you have some equations, but getting an estimate for this particular device is important. How are the velocity in the large and small diameter sections of the tube related? What implications does this have for cleaning? What is a reasonable number or range for fluid flow rate?

Our design team has discussed your comments of our preliminary work and updated our report to respond to your requests. The executive summary was revised considerably in order to make this section more succinct. The new executive summary focuses more on the main conclusions from our research and is filled with the most significant results from our product dissection and analysis. Below you will find a more detailed response to each of your points:

  • Please include a picture of the product
    • While pictures of the bilge pump and siphon were previously shown at the top of each of the respective sections, a combined picture of these two devices was added to the main report page to clarify what we refer to in the report.
  • Be sure to consider issues of cleaning and storage in addition to use. Also, the siphon appears to be used both to remove water from the tank and to clean gravel at the bottom of the tank. Are these two uses distinct?
    • Analyses of cleaning and storage aspects for the bilge pump and siphon can now be found under the Product Use sections of each of the respective product pages. Additional discussion of the uses of the siphon has been added under the Product Purpose sections of both the main report as well as the siphon-specific section.
  • You might consider alternative uses for the siphon, such as emptying a waterbed or hot tub.
    • Alternative uses for the siphon were previously considered in the Consumer Demographics section of the main page. During our updates, we added a short sentence to the Product Purpose section in order to make this point more evident.
  • Product function descriptions are relatively clear, but a figure would help. Additionally, some explanation of the physics of how a siphon functions would be helpful. The videos are interesting, but some explanation of what we are supposed to be looking at in each is in order.
    • In order to convey the product functions more clearly, we added visuals to the bilge pump and siphon pages that illustrate the process described in the text above the images. Furthermore, a short section on the physics of a siphon was added to the siphon page to offer a high-level explanation of the function of a general siphon. In order to add to the descriptiveness of the video titles, short descriptions of these videos were added to the report to give the reader a better understanding of the video content.
  • FMEA: We are surprised that hole or wear in the tube would be more likely than blockage. It seems that tube blockage is a quite likely failure mode that could be difficult to correct if the right (wrong) sided rock were to become jammed.
    • In both the original report and the new one, the blockage mode of failure is more likely to occur than wear. The occurrence parameter for blockage is rated as a 6, while wear is rated as a 5. However, the blockage RPN was originally lower than that of the wear failure mode due to the detectability parameter’s slightly lower value for blockage. A lower D-value was initially chosen for tube blockage, as our group believed that any significant impedance in the clear plastic tube would be easily visible. However, after significant group discussion, we determined that the detectability value should be the same for both blockage and wear, as each would be approximately as likely to be observed in the event of failure. Thus, our revised FMEA analysis indicates that blockage would be the most significant mode of failure for the siphon, which is consistent with your comments.
  • For the bilge pump, it is not clear how the flapper attaches to the rest of the device. Also, was the plunger valve removed from the rest of the assembly? How is this assembled?
    • Details regarding the flapper and plunger assembly were added to the Bill of Materials section of the bilge pump page to describe the assembly of these components.
  • Numerical analyses
    • In order to response to the client needs in these areas, pertinent changes were made to the quantitative sections of the main page, the bilge pump page, and the siphon page. In addition to finding an estimate of the volumetric flow rate to determine the head required to move water through the system, we significantly updated the calculations of the force needed to move the bilge pump handle. In order to do so, we complemented our water weight calculations with approximations for the frictional force and the drag force acting on the plunger. A comparison and summary of these values was also included in the bilge pump section and also in the executive summary.
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