I now have a VF pump and was curious if some of the pump experts here might have some ideas of flow and turnover changes on my old 1 hp single speed pump. I have single runs of 1.5" piping, and no solar, heater, or other features. Based on flow and pressure on my VF, I'm guessing that the old pump probably pumped about 50 GPM, showing about 15 psi on my CLEAN 48 sq ft DE filter.
When dirty, the filter could get as high as about 30 psi, with the old single speed pump. The flow was really low then. Since the flow was really low with the old pump with a really dirty filter, I'm guessing the turnovers decreased greatly over time from clean to dirty filter.
1. Any guesses from the experts, how low the flow may have been with the dirty filter at 30 psi? (The clean filter at 15 psi was about 50 GPM I think, comparing to new VF.) My guess is 20 or less GPM, but would like to hear anyone else's thoughts.
2. Would the GPM decrease on a linear relationship from the clean filter at 50 GPM, and 15 PSI? That is, say the clean filter (50 GPM, and 15 psi) went to a dirty filter at 30 psi, (say a drop of 30 GPM to 20 GPM, for the 15 psi increase). Would this be a linear change, so every psi rise of 1 psi, would mean a 2 GPM flow decrease?
This means any turnover estimates I had done using only clean filter would be too high (on average), as the GPM would steadily be decreasing until the dirty filter.
Thanks for your thoughts,