Quote:
Originally posted by myv65
This one is definitely getting way out of hand. Here's my last comment on this thread.
Right idea, but wrong final answer. Pressure drop and flow don't quite work so easily as summing up inverses. In general, pressure drop varies with velocity squared. P/Q curves for pumps are never flat (unless you've got a positive displacement pump, then who cares). The only way to really know is to measure the results.
[rant warning]
The following is directed to no one in particular:
This whole relationship between flow and resistance is probably the biggest misunderstanding people have when trying to determine how to plumb multiple blocks and/or radiators. There is no single method that is guaranteed to yield the better result. I've been dragged into numerous "discussions" on this topic and regardless of whether I take the "simplified, analogy-filled" approach or the hard-core theoretical approach there are always those that insist it must be best one way in all cases. It simply isn't true.
I've long since resigned myself to the conclusion that not everyone will ever "get it". I do not lose sleep over those that would insist their will in the face of overwhelming contrary evidence. I try very hard to form one of two opinions about people that I "meet" on the forums. I either conclude they're on the up-and-up and doing their best ("best" whether learning or sharing knowledge) or I conclude it is not worth my time to bother with them.
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I was trying to get a line of reasoning of what he really meant from the long posted paragraphs down to a single short description of what was being discussed. What was failed to be said in discussion is that the same percentage of reduction in orifice size would need to be placed as the second restriction in order for the same percentage of flow restriction to be imposed as the first.
In short, I was just trying to find out what GeminiCool was trying to say. And this was his answer to the querry,
quote by Geminicool, "Yeah I guess that's about right, but I think I felt the drop would be a little less drastic, since 50% is not ignorable. I did not think in terms of pressure drops across fittings. I simply looked at it from the perspective of the pump. " end quote
myv65, you are of course correct. Vagueries should be questioned to clear up long rambled roads that lead to nowhere
