According to the paper from the Portland State University... using up to 3 nozzles is still within the standard. That answers one question I had.
The nozzles used are: 0.75", 1" and 1.6". That gives this tester the following cfm ranges:
(as stated by the man)
0.75" only: 9 to 19 cfm
1.0" only : 15 to 35 cfm
1.6" only : 39 to 96 cfm
0.75" and 1.0" : 24 to 40 cfm
0.75" and 1.6" : 48 to 71 cfm
0.75" and 1.0" and 1.6" : 63 to 150 cfm
A simple addition, as expected, but max for {0.75" and 1.0"} ought to read 54 cfm (instead of 40), and max for {0.75" and 1.6"} would read 115 cfm (not 71). Not sure why there's a difference.
The cfms calculated are consistent with a dP range of 1.0"wc to 3.0" wc (both our calculations appear to be off, but mine are closer
). I don't understand why the graphs in that paper have a pressure range between ~0 and ~45 Pa: 1.0" wc is 249 Pa.
Am I missing something here? I'd like to master the calculations. That'll be my goal this week. I'll retry the calcs at 60F and 32F, to see if I can sort out the differences.
I read you (clear) about the screens: I just wanted your opinion on wether the egg crate would suffice for us, or if we should consider looking at twpinc.com (I've ordered samples from them in the past, for water filtration). Going over the site quickly, it is possible to replicate the 60, 50 and 45% open area in mesh, but it might be pricey (i.e. in aluminium, ~4.00$ per square foot, off of a 36" wide roll).
I don't understand you on "max velocity differences permitted". We won't be anywhere near 400 cfm, right?