Pipe size for separate trash can baffle on a 2HP HF DC?

[mailalan]

I have the Harbor Freight 2HP dust collector with the Wynn filter. I want to build a two-stage system with a separate trash can pre-separator before the DC. What I mean is I dont want attach Phil's baffle directly to the dust collector blower as some have done. I want the baffle on the trash can before the air flow gets to the DC.

I'm a little confused with all I've read. Is a 4 inch pipe not big enough for this setup? Would that kill the air flow with a 30 gallon can? Do I need 6 inch piping with a 30 gallon can? I'm hoping since so many have experience with Phil's baffle that someone can give me their opinion on air flow and pipe size?

Thanks!
Alan

[dbhost]

Not sure where you got your info, but there are several folks on here that have build and use everyday a 30 gallon or larger separator with 4" pipe from the HF DC... I personally use 2.5" with a 20 gallon separator and a shop vac. Just make sure your top disk is cut and rabbeted correctly so that it gives you a good seal, and you might want to use clear silicone to seal the inlet / outlet adapters to the lid...

FWIW, using a pre-separator is probably the best idea, since the large stuff that otherwise would tear up your impeller, drops out of the air stream before it even gets to the impeller...

[Greg McCallister]

I have a version listed below in this forum with 6" duct and it works exceptionally well.
4" will work as others have done. All depends on your personal talents with metalworking, cost limitations, space and what you are trying to acheive. Having used 4" in my shop and now using 6", I will never go back to 4". Honestly there is no comparison in air flow.

[mailalan]

Greg it was your post that I had seen that said 4" hurt your airflow. I've just about decided to use 5" even though that is more difficult to find since all the HF DC connections seem to be 5 inch. Thanks very much for the information!

- Alan

[Greg McCallister]

Alan,
I tried to go the 5" too but found it was real difficult to obtain except for the stuff you find a Home Depot and all that is a available is metal. Don't get me wrong, metal duct is good but I do not think it flows as well as PVC duct, in fact I think there is something mentioned somewhere about that. However, 6" PVC could be a problem obtaining too but do not use the heavy walled PVC but the thinner stuff sometimes referred to as Sewer and Drain or S & D (much cheaper but still not cheep). You might have to go to a plumbing supply to get it if you have one in your area. I made a inlet to the impeller housing to accommodate the 6" duct (you can see it in my post).
Believe me I have a bunch of 4" and 5" duct in my garage in the rafters I wish I never purchased. If I knew what I know now, I would of went 6" from the beginning and saved a boat load of money and frustration.
I will be making a new post soon as I am in the process of increasing the outlet size to 6" and modifying the filter. Been really busy working on the kitchen cabinets and such.

[mailalan]

Thanks Greg, that is the very valuable information I was looking for. I am very interested in seeing your pictures.

Thanks,
Alan