After I posted some incomplete test results recently Michael Clark pointed out that by relying on supplied CFM data I did not really know how my system was performing. I agreed, and decided to go further with this. I was lucky enough to find A Dwyer 471 hot wire anemometer on E-bay for a reasonable price so I bought it. Here’s what I came up with.
My dust collector is an Oneida V3000. It is a 3hp system with a 14.25” backward inclined cast aluminum impeller and a HEPA filter. The filter is well seasoned and was cleaned prior to the testing. Ductwork is 6” PVC.
I used the following test equipment; UEI EM151 digital manometer, and a Dwyer 471 hot wire in duct anemometer.
The Claimed CFM numbers are extracted from an Oneida published system curve for the V3000. SP measurements were taken just before the cyclone inlet. Air velocity measurements were taken from the longest straight piece of pipe in my system, following Dwyer’s guidelines as closely as practical. All FPM measurements were rounded down to the nearest 25, and I used a divisor of 5 to calculate CFM from FPM. Since the accuracy of the Dwyer 471 is +/- 4% I didn’t feel compelled to calculate to the exact decimal.
The results were as follows;
SP Claimed CFM Measured FPM Calculated CFM
12.4(max)<100----------375------------------- 75
12 -------200------------- 925------------------ 185
11------- 400------------ 2050------------------ 410
10------- 525------------ 2950------------------ 590
9 ---------650------------ 3700------------------ 700
8 ---------775-------------4050------------------ 810
7 ---------900------------ 4550------------------ 910
6-------- 1000------------ 5100----------------- 1020
5-------- 1100 ------------5450----------------- 1090
4 --------1200------------ 6100----------------- 1220
3.8(min) 1250 -----------6200----------------- 1240
Somewhat surprisingly, my results fell almost exactly on top of the published performance data. Now I can rely on the published curve and the readings from the manometer that I leave installed on the cyclone inlet to gauge CFM as I use and modify the DC.