I have completed and installed an air scrubber built along the lines of the unit Don Kornfeld described in an earlier thread. The unit is 17 x 21 x 34″, quieter than I anticipated, and seems to move a lot of air. My question is: How much air is it moving? How do I determine the ballpark static pressure with the filter arrangement I’m using?
The intake filters are close to the ones recommended by Don, i.e., a Web electrostatic (16 x 20), a 3M Filtrete 1000 and a Filtrete 1250. The blower unit is a Delhi 407 driven by a 1/4 HP, 1725 rpm GE continuous duty motor. The blower speed is 1380 rpm, and the power curves provided by Delhi indicate that with a static pressure of 0 inches (no restrictions to air flow) I should get almost 900 CFM. At 1/2″ static pressure, the CFM drops to around 600 CFM. At 1″ pressure, the flow drops back somewhere around 300 CFM.
I’ve attached a couple of snaps of the unit and the power curves chart. Any advice would be appreciated!
Regards,
Ron
BTW, I very much aware that the cabinet isn’t fine woodworking. However, it’s sealed, strong and seems to do the job.
Replies
Ron,
Your finished scrubber looks excellent, I'm glad my designs were so helpfull. You can actually increase the efficiency of the air flow into the blower by sealing the internal fairing (air deflector) flush with the side of the box.
Well done!
Dan Kornfeld, Owner/President - Odyssey Wood Design, Inc.
The most reliable way, and the easiest, is to measure it directly. You want the pressure difference between the fan inlet and the fan outlet. Take a piece of clear plastic tube. One quarter inch diameter would be ok. I can't really tell from your photos, but you need to drill a hole in the box on the suction side of the fan and on the discharge side of the fan. If the suction is in open air, then you only need one hole on the discharge. Put a little water, with a touch of food coloring (or a drop of Kool Aid or something) in the tube. Arrange the middle of the tube into a U-shape, trapping the water like water in a trap. Put one end of the tube in each hole. With the fan off both water levels will be equal. Turn on the fan and the water levels will offset. Measure the difference accurately with a ruler in inches. The difference in the heights of the two levels, from one to the other, is the static pressure in inches water column (in. w.c.). That's the pressure to enter your fan curve with.
What you are creating is an instrument called a U-Tube Manometer. It is from such an instrument that the units of inches water column were derived.
Edited 3/29/2004 10:05 pm ET by WAYNEL5
Thanks for the prompt reply. I have a few feet of clear tubing stuffed away somewhere in my shop, so I'll give this a try the next time I'm up on the step ladder checking the filters.
Regards,
Ron
I hope it works out well.
You live in Ottawa, Ontario? I lived in Canton, NY, which is just across the border from Prescott, for 18 years. Ottawa was one of my favorite places. I miss the radio show As It Happens, on CBC Radio One too. And Swiss Chalet -- there are no good rib places here.
You don't have Tim Hortons either! I make frequent trips down to West Virginia to visit family and the first thing I do when I get back across the border to stop for a good cup of coffee!
Regards,
Ron
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