Great video. Does anyone know why it's more efficient to have some head rise across the pump? If partially closing the globe valve increases friction resulting in losses, wouldn't it be best to keep the globe valve open with zero head rise across the pump?
You will always have a head rise across the pump at any flow. It definitely would be more efficient to select the pump that will provide the flow you need so no throttling is required but that’s only in a perfect world. Very quickly, the impeller will start to wear, the pipe will corrode and get rougher or build up will occur and reduce the pipe diameter. Now the pump is maxed out and cannot deliver the required flow. Unfortunately, some energy must be wasted through valves to keep the system working long term.
@@RiffMusic1970thanks! I understand this a lot more now. Saving this video in case I ever forget this stuff. Explained much better than it was in school
I have a question for the last sentence. “For warmer water, the pump should be placed lower, so the inlet pressure will be lower to avoid boiling of the water.” I think it will make the inlet pressure higher to avoid boiling.
Thank you Mr. Sellens for sharing this explanation.
Best regards from Colombia.
Great videos Dr. Sellens! Your material is all I've looked at for 241 this year.
Kevin Mulligan Thanks Kevin -- you should still check in with your instructor to avoid exam surprises...
Kevin Mulligan I agree! Great video Rick Sellens!
Great video. Does anyone know why it's more efficient to have some head rise across the pump? If partially closing the globe valve increases friction resulting in losses, wouldn't it be best to keep the globe valve open with zero head rise across the pump?
You will always have a head rise across the pump at any flow.
It definitely would be more efficient to select the pump that will provide the flow you need so no throttling is required but that’s only in a perfect world. Very quickly, the impeller will start to wear, the pipe will corrode and get rougher or build up will occur and reduce the pipe diameter. Now the pump is maxed out and cannot deliver the required flow.
Unfortunately, some energy must be wasted through valves to keep the system working long term.
@@RiffMusic1970thanks! I understand this a lot more now. Saving this video in case I ever forget this stuff. Explained much better than it was in school
I have a question for the last sentence. “For warmer water, the pump should be placed lower, so the inlet pressure will be lower to avoid boiling of the water.” I think it will make the inlet pressure higher to avoid boiling.