Per the request of several active members of the HBT kegging forums, I have upload a derivation of the proper analysis of hose length, as a dissenting opinion to Mike Soltys calculator (for reference, here is a link to Mike's calculator).
http://www.mikesoltys.com/2012/09/17/determining-proper-hose-length-for-your-kegerator/
I attempted to post a reply on Mike's web page around a month ago, and as my piece has not yet been published to the site, either the site is currently abandoned, or the author has no interest in addressing shortcomings in his methods. In the attached .pdf, I have provide some insight, as well as a simple, and complete, derivation for how to calculate the required hose length in a closed channel fluid system.
After reading through Mike's calculation, 3 issues immediately came to my attention. First, Mike fails to consider the energy within the fluid as it leaves the faucet; Mike does not address the velocity term at the faucet. Second, Mike makes a bold assumption that all of the energy loss within the system is due to pipe friction, rather than a combination of pipe fittings and pipe friction, I summed this up in the previous thread as:
"Second, and more damning, is that he assumes that all the energy loss in the system comes from friction within the tubing, rather than the connections within the draft system. This tells me the author has a poor understanding of how closed channel fluid systems operate. He probably read that friction losses in the pipe are called "major losses", and that losses in the fittings are called "minor losses". In many fluids problems, that is correct, but in many fluids problems, we are dealing with 500+ feet of tubing, not 10 feet"
Third, Mike assumes that the user is able to adjust the flow velocity, now that may be true for those who have flow control functionality, many users (myself included), do not have this capability, so the pour speed is based on the physical parameters of the kegging system, rather than a chosen flow rate.
If there is sufficient interest, I may be able to write an executable that I can host on a 3rd part site that is based off of my analysis, and would allow the user to compare to Mike's solution, and the hose length that works for their system. As I do not wish to purchase and maintain a domain for hosting the site, it would likely be a download executable, with the source code, rather than a web based application.
Please excuse the handwriting, I realize it is anything but easy to read, I tried to comment everything out in the .pdf to ease reading....
I am open to feed back, if there are any questions or concerns, or if you believe you have found an error or incorrect consideration, please let me know...
http://www.mikesoltys.com/2012/09/17/determining-proper-hose-length-for-your-kegerator/
I attempted to post a reply on Mike's web page around a month ago, and as my piece has not yet been published to the site, either the site is currently abandoned, or the author has no interest in addressing shortcomings in his methods. In the attached .pdf, I have provide some insight, as well as a simple, and complete, derivation for how to calculate the required hose length in a closed channel fluid system.
After reading through Mike's calculation, 3 issues immediately came to my attention. First, Mike fails to consider the energy within the fluid as it leaves the faucet; Mike does not address the velocity term at the faucet. Second, Mike makes a bold assumption that all of the energy loss within the system is due to pipe friction, rather than a combination of pipe fittings and pipe friction, I summed this up in the previous thread as:
"Second, and more damning, is that he assumes that all the energy loss in the system comes from friction within the tubing, rather than the connections within the draft system. This tells me the author has a poor understanding of how closed channel fluid systems operate. He probably read that friction losses in the pipe are called "major losses", and that losses in the fittings are called "minor losses". In many fluids problems, that is correct, but in many fluids problems, we are dealing with 500+ feet of tubing, not 10 feet"
Third, Mike assumes that the user is able to adjust the flow velocity, now that may be true for those who have flow control functionality, many users (myself included), do not have this capability, so the pour speed is based on the physical parameters of the kegging system, rather than a chosen flow rate.
If there is sufficient interest, I may be able to write an executable that I can host on a 3rd part site that is based off of my analysis, and would allow the user to compare to Mike's solution, and the hose length that works for their system. As I do not wish to purchase and maintain a domain for hosting the site, it would likely be a download executable, with the source code, rather than a web based application.
Please excuse the handwriting, I realize it is anything but easy to read, I tried to comment everything out in the .pdf to ease reading....
I am open to feed back, if there are any questions or concerns, or if you believe you have found an error or incorrect consideration, please let me know...