3 dust collector questions.

[Jim Horton]

I have a small shop (16X20) and I heat it with a pellet stove.
My large power tools are TSx2, RAS, planer and band saw.
I inherited a Jet 1900A that has one large 8" inlet with a cap that reduces the intake to three 4". Due to its size, there was no other choice for me except to build an attached extra room (6X10) for the DC.
Because of heat loss I want to return the air to my shop thru a hole or holes that are covered by a ? micron felt filter cloth, so:

What size hole(s) is/are needed for the return?-the best info so far is 2" larger than the largest inlet which is 8".

Is it safe (for the motor) to block one of the three 4" inlets on the cap?

99% of the time I will only be using one of the inlets should I open a second blast gate?

thanks all!

[David Kumm]

I'm assuming you are leaving the bags on ( or Cartridge ) and then returning clean air through the final filter? I would make it bigger. Reduces the back pressure from exiting the hole and will stir up the dust in the shop less. Plugging a port will reduce the amp draw so it will not over heat the motor. Has the opposite effect. I would take off the 4" ports and reduce the 8" to 6" and run that to a duct and then run off that main line. Probably won't need to worry about second gates then. If you leave the three 4" on and run 4" from each, opening a second gate won't gain you any cfm on the first. Dave

[Jim Neeley]

Jim,

Please pardon the cut and paste from another thread. I hope you find this usefull.

The answer is a pressure drop (flow restriction) vs. size so it depends upon how much air restriction you are willing to deal with vs noise abatement. Thus there is no *one* answer.

In my opinion, and only my opinion, there's nothing wring with using "next pipe size" as a lower end for the return area. On Ed and Matt Morano's (Original Clearvue Cyclone owners) noise level video: Clearvuecyclones ==> Video Central ==> Sound level video they show what appears to be about 10x20 for a vent, which equates to about 16" diameter. You may want to go to the web site and view the video; they have a good idea for muffling the noise while directing the warm air from the top of the enclosure back into the room but down low where it'll mix with the room air.

Jim

After making this post, I was reading on Clearvue's forum where they recommend a return air area sized 3-4x the size of the inlet duct. They suggest that you make it rectangular and install a louvered face plate on the front, for appearance. For 6" round duct that would be something around 10x12"; for 8", about 10"x20".

As for ducting and that large collector, I would not go smaller than 6" for your mains or you will lose too much air due to friction. Where possible, modify the dust pickup on your tool to 6" (starting with the planer); where not, make the transition as near as feasible to the tool.

Also, it's best to locate your tools requiring the most air as close as feasible to the DC.

Jim

[Chris Damm]

I have that same DC and get rid of the 3x4 adapter. I ran a piece of 8" pipe and then reduced to my 6" main runs. As for the return air I went to Lowes and bought a 16" sq. grate and cut a 14' sq. hole in the ajoining wall. On the DC side I built a bracket to hold a furance filter. It works great. I bought 2 grates in case I needed them but 1 was all I needed to keep the velocity down. The grate has fins on it and I angled them down. If you go too small with the return the air will be moving has fast as the DC sucks.

[Jim Neeley]

Not only will it move quickly but the pressure drop used getting back into your shop is vacuum that could otherwise be used to suck more dust!!