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Originally Posted by unregistered
ok, how is that different ?
C/W vs. Flow + Flow vs. Head Loss = C/W vs Head Loss
no ?
'cuz thats how I've been doing it
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Sorry Bill, my intentions here are to keep achievable flow always on the graph where people can see it.
The issue I have with a C/W vs PD graph is that when people start linking to it without flow information, then it can present very low P.D. blocks in an overly favorable light. If a low P.D. block matches the performance of a high P.D. block at 1mH2O, but the high P.D. block was pushing 2LPM, while the low P.D. was pushing 15LPM then that puts a remarkably different perception on the pump that is needed than merely looking at P.D. alone. One cannot easily map such information back to the commonly available pump PQ curves.
With a Flow vs Head loss graph, one can very easily grab a pump PQ curve, overlay it, look at the intersection of the two curves, find the flow rate, and then match that up to the block's C/W on the C/W vs flow graph. Yes, I know that there will be other restrictions, but it'll help if stops the users from looking at the outmost right end of C/W vs flow curves, and start focusing on the best that they could achieve given a pump in hand.
i.e. A C/W vs flow and a P.D. vs flow graph is more immediately useful, and inherently easier to use and understand, for the lay-person, with less chance of them making false conclusions due to mis-mapping a C/W derived from a P.D. vs C/W graph back onto the C/W vs flow graph.
Pump's PQ curves are already head vs flow, and it makes most sense to me to keep to that data-style presentation since people are already used to it, and even more so, can finally get to see a real-world use for it.