Dust collection question

[frigator]

Its been sometime since I set up a dust collection system. Concerning the wyes or lateral T's, whatever you call those 3 opening fitting we use for drops, is it preferable to bring them out of the side of the main line, then turn them down with a 90, or orientate the wye downward so you just need a 45 to head straight down.

I recall chips collecting at the blast gate when I brought them straight down before...sometimes a lot if didn't open the gate for a long time. It was no big deal, when you open the gate the chips would fly right up. But the gate would sometimes get chips clogged in it. So I am thinking of coming out the side this time. What do you guys do?

[Robert Adams]

My thinking is make the pipe as straight as possible. That means if a drop is under the main line run the wye down. If it's a distance from the main run it laterally.

[ed kerns]

Always good to avoid a 90 degree turn if you can.

[frigator]

Agreed, and try to get the long 90's. I remember talking to Bill Penze many years ago and he recommended a run of straight pipe out of the cyclone and wyes coming out of the side. I notice many people immediately have a turn as they come out of the cyclone cause their inlet is so low. I put mine on a stand, bottom of inlet is 7ft, so I can run pipe straight out of the inlet. Here is what he says on his website:

"Below is a drawing of a well designed small shop duct layout. Note this system uses a 3+ hp blower needed to support an 8" diameter main with only 6" down drops. Moreover, the down drops all exit horizontally and go for a while before turning downward. This makes sure that stuff does not build up in down drops with closed gates to create plugging. Also, for maximum efficiency, particularly with a cyclone, this layout keeps a straight run that is at least 4' or longer going into the inlet. This keeps the incoming air very smooth making for far better material separation and improved efficiency as turbulence kills efficiency."

http://billpentz.com/woodworking/cyclone...ing_design


He has a lot of good info on duct design. My first system he told me to run only 6in pipe...we ran everything 6in right up to the 4in inlets and only there used a reducer, and I also modified some machines to put in bigger ports.

[fredhargis]

I've done both, but I only use a 90 if there is absolutely no way (space wise) to point the 45 down. I didn't give this any thought until you mentioned it, but the only time I've had chips settle down was on the corners that had the 90's....at least that I ever noticed.