Several months ago, I purchased the Super Dust Gorilla 5 HP from Oneida. The specifications on the Super Dust Gorilla were:
• 5 HP US made Baldor motor – 19.5 Amps
• Backward Inclined Cast Aluminum Impeller – 15”
• Max Performance 1860 CFM at 2.5” SP
• 8” Inlet
• HEPA MERV 16+ Filter
• Filter 110 sq. ft
I posted a couple of days ago the measured performance curve for this dust collector. That was all fine and somewhat interesting. But, the important part is not the performance curve but how well is works inside the shop hooked to the individual tools.
My shop is about 15 ft by 35 ft with the dust collector located just outside one end of the shop. It is piped using two 8” 90 long radius elbows and then reduced to 6”DWV. The 6” DWV runs for about 12 feet and has drops for the table saw, planer and other larger tools. The next 15 ft is run with 4” PVC.
The testing in my shop was done in a similar manner as described in the previous part of this blog. A digital thermal anemometer and digital manometer were used. The same holder was used for the digital thermal anemometer and six measurements were made across the diameter of the 6” pipe.
ALL OF THE FLOW MEASUREMENTS AND STATIC PRESSURE MEASUREMENTS WERE MADE IN THE SAME PLACE. Different gates or combinations of hoses and equipment connections were made to determine the flows under various conditions. The testing location is shown in the following diagram.
The results are summarized below. Please understand that the numbers on this diagram represent the flow with only that area open. The 1658 CFM was taken at the dust collector with an open 8” duct.
The flow of 1360 CFM was taken at the same testing point from the previous figure and represents just having the 6” Wye open. Similarly, the 1345 CFM flow at the 6 inch gate represents the flow with just the 6 inch gate open.
As one can see, the reduction of the duct from 6” to 4” and the 4” gates reduced the flow down to about 600-820 CFM.
In the first section of pipe my shop, I am using 6” DWV pipe, 6” blast gates and then reducers, with 5” flex hose for the drops to equipment. The following schematic shows the hookup to the 4” port on my SawStop. Again, the flows were determined for each point by gradually adding components. First, a flow measurement was made with just the wye open for 1360 CFM, then the blast gate was added which resulted in a flow of 1345 CFM. Similarly, the 6”- to 5” reducer was added and the flow dropped to 1071 CFM and with the addition of 10 feet of 5” flexes hose, the flow dropped to 900 CFM. Finally, a 5” to 4” reducer was added providing a flow of 720 CFM and when actually connected to the SawStop the flow was 670 CFM.
I got similar flows when hooked up to the dust port of a 15” Jet planer.
As a comparison, I hooked up a 6” to 4” reducer to the 6” blast gate and then 10 feet of 4” flex hose. The 6” to 4” reducer results in a large drop in air flow. But the end result is similar to using the 5” hose and then 5” to 4” reducer. Both provided about 720 cfm at the connection to the tool. I had expected that the 5” hose would perform better but the bottom line is that both are reduced to a 4” connection to the saw.
I have been using the following setup to connect to my planer including the 4” elbow for convenience. The test results show that the elbow results in a 120 cfm drop in air flow and I will stop with this practice.
After the first 12 feet of my shop with the 6” DWV, I am using 4” PVC. This area has my router table, band saw and drill press. The measured air flow to the drops for these machines is 600-800 cfm at a SP of 9.75 – 9.9”. For the time, this is adequate and does a pretty good job. As I work to improve dust collection this may be an area for improvement. However, with the machines only having 4” ports on them, I do not anticipate making any changes in the near future.
One last item….I took all of my data from both the 8” duct tests and the shop tests and plotted the flow versus static pressure. Using Excel, I had a trend line calculated using a polynomial fit. The data fit the curve extremely well. In the future, if I want to know the flow, I can simply measure the static pressure and read the flow from the curve. For instance, if I would read a static pressure of 9 inches, I could look on the graph and find that corresponds to a flow of about 900 CFM.