How to vent fine DC dust outside

[Jeffrey Schronce]

I want to get DC (possiably HF 2HP) and put it in the attic of my shop. I want to vent the fine dust outside. This could easily be accomplished with a traditional Cyclone but I don't want to spend $700 one. Could I use a trash can lid cyclone pre or post impeller to sepearate out the large items and take the output of the cyclone out side through a dryer vent type contraption installed on the wall?
I would never connect the bags in this circumstance, instead putting the trash can in the area of the machine the bags normally occupy. This would of course result in a much shorter machine without the bags (height is not a issue with my application but I mention anyway).
Second, putting the DC in top of the attic with a 10 foot ceiling, will it develope enough CFM to work properly? The duct work would run straight down from the DC to the shop floor where it would splice, one run going to table saw (7 ft away) and one going to CMS (being reduced to 2.5 " at about 10 ft from drop.
Thanks in advance!

[jnesmith]

Is your shop heated/cooled?

[Jeffrey Schronce]

I understand potential heat/cooling loss. It is neither heated or cooled. I was out there until 3:30 last night. It was 30 degrees outside last night. No heat or insulation in shop (yet). Heat will be installed shortly No AC in future (unless I run across a good deal on a split).

[woodsmoke]

1st I don't think you will have enough Static pressure to pull the dust that high and have enough CFM to keep the fines/dust suspended to get it outside.
2nd The amount of heat loss will be unreal when the DC is running. The shop will be the same as the outside temp in no time. I know I can't work safely in my shop until the woodstove gets things up to about 55-60 degrees.

[LarryG]

Kent is correct about the heat loss. The (in)famous HF 2HP DC is rated at 1600 CFM but the mfrs all lie like a truckload of rugs; IIRC Wynn Environmental measured the actual throughput of this unit at something like 550 CFM. But that's still enough air movement to theoretically empty a one-car-garage-size shop (10' x 24' x 8' ceiling) in 3.5 minutes.

I cannot advise you on how long your runs can be, other than to say you should keep them as smooth (i.e., hard pipe rather than flexible hose, with a minium of turns and fittings) and as short as possible. I'm guessing that the setup you propose will tax the HF unit pretty heavily. My longest run, using 4" HF hose and including all fittings, is about 12 feet. This year I may be moving the DC to a location that will add about six feet to the run. If I do, I'll be switching to hard pipe wherever I can.

[Tom Miller]

Re: vertical DC runs -- If you have 550 cfm flowing in a 4" pipe, I'd think you could easily pull your dust & chips up a 20' vertical run with little problem. That might even be enough to lift small cutoffs.

I think the magic number for air velocity to keep dust/chips entrained is 3500 fpm horizontal, and 4000 fpm vertical. 550 CFM in a 4" diameter is over 6000 fpm.

And I'm guessing 20' of smooth wall DC pipe has about the resistance to flow as 5' of flex.

But Larry's calculation of rate of air change is the one that should raise your eyebrows. Six changes per hour is considered pretty good, but your heater/AC won't keep up with 20.

Regards,
Tom

[Jeffrey Schronce]

quote:Originally posted by Tom Miller

Re: vertical DC runs -- If you have 550 cfm flowing in a 4" pipe, I'd think you could easily pull your dust & chips up a 20' vertical run with little problem. That might even be enough to lift small cutoffs.

I think the magic number for air velocity to keep dust/chips entrained is 3500 fpm horizontal, and 4000 fpm vertical. 550 CFM in a 4" diameter is over 6000 fpm.

And I'm guessing 20' of smooth wall DC pipe has about the resistance to flow as 5' of flex.

But Larry's calculation of rate of air change is the one that should raise your eyebrows. Six changes per hour is considered pretty good, but your heater/AC won't keep up with 20.

Regards,
Tom

10 ft vertical - 6ft and 10 ft horz.
I'm glad to see that you think it will do it.
I am concerned a bit about heat loss. On the plus side, it should make for a nice attic fan for summer! lol.
I think I may give this a try. I'm not going to install heat until next fall. During winter months next year I may have to attach the bags.

[LCHIEN]

The volume of fines is relatively small.
I'd go ahead and use a fines filter e.g. some 1 micron or smaller bags - to trap them - you'll hardly ever have to empty it since you plan on capturing the coarse stuff in a trap. That will solve the heat loss problem and keep you from polluting.

[Jeffrey Schronce]

quote:Originally posted by LCHIEN

The volume of fines is relatively small.
I'd go ahead and use a fines filter e.g. some 1 micron or smaller bags - to trap them - you'll hardly ever have to empty it since you plan on capturing the coarse stuff in a trap. That will solve the heat loss problem and keep you from polluting.

It's hard to think of wood as a pollutant, of course it is hard to think of it as a health hazard as well! I do live on over 250 acres, so I am not concerned about it leaving my property, however I think I will keep the whole thing inside, due to environmental impact of heat loss.
Cyclone first?

[LCHIEN]

quote:Originally posted by Jeffrey Schronce

quote:Originally posted by LCHIEN

The volume of fines is relatively small.
I'd go ahead and use a fines filter e.g. some 1 micron or smaller bags - to trap them - you'll hardly ever have to empty it since you plan on capturing the coarse stuff in a trap. That will solve the heat loss problem and keep you from polluting.

It's hard to think of wood as a pollutant, of course it is hard to think of it as a health hazard as well! I do live on over 250 acres, so I am not concerned about it leaving my property, however I think I will keep the whole thing inside, due to environmental impact of heat loss.
Cyclone first?

Typically people like to put the cyclone before the blower, it keeps the chunks and ocassional screw, nail or bolt from whacking your impellor (which can be at least rather startling, and at worst, damge it).

It's my opinion from reading, that the trash can separator is a poormans cyclone and a properly tuned 2 HP system will suck it empty.
Bigger systems use scientifically computed cycloes of certain sloping sides and a certain heigh to achieve the cut point desired. They also put the blower (or sucker as the case is here) on top of the cyclone output to achieve minimal loss.

[Jeffrey Schronce]

quote:Originally posted by LCHIEN

I'd go ahead and use a fines filter e.g. some 1 micron or smaller bags - to trap them - you'll hardly ever have to empty it since you plan on capturing the coarse stuff in a trap.

What is the "trap" which will capture coarse stuff. I was thinking trash can cyclone, but in seperate post you advise I will likely not get much mileage out of that.
Should I just opt for plastic bag on bottom bag and canister filter on top? What canister filter would be recommended by this fine group? Someone mentioned a Wynn ? Not familiar with this. What is the approximate cost?

Edit : Don't think I think that canister filter. Think I will go with below without trash can cyclone.

[LCHIEN]

What is the "trap" which will capture coarse stuff. I was thinking trash can cyclone, but in seperate post you advise I will likely not get much mileage out of that.
Should I just opt for plastic bag on bottom bag and canister filter on top? What canister filter would be recommended by this fine group? Someone mentioned a Wynn ? Not familiar with this. What is the approximate cost?

Edit : Don't think I think that canister filter. Think I will go with below without trash can cyclone.

i think in an earlier post you said you were going to use the trashcan separator. I think I said that some people find it works and some find it doesn't. I think the reason why it works and why it doesn't depend upon airflow and restriction - those with some restriction find the air flow is low enough it works and those with better flowing systems find it sucks all the stuff out of the can. Those who claim it works have sufficient air flow for their needs and are happy - so that's fine. Those with better air flow are probably happy, too. Those with restricted airflow that has caused problems such as plugged lines probably did something to fix it - maybe removed the trashcan.

so I don't know which camp you'll fall in.

My personal use has no trashcan separator, I have a HF 2HP DC, use a Grizzly canister/cartridge filter and a plastic bag on bottom. I'm about to empty the bag for the first time as the bag is more than half full and its seems like its sucking stuff out of the bag.

I personally like the canister system, it makes sense to this engineer.
The Wynn has been made available since I got mine - I'd go with the wynn if i had to do it over.

One of the 2 main reasons for the canister is to replace the bottom cloth filter bag with a plastic bag that's easy to empty. The canister has 7 times the area of a bag so the lower bag no longer needs to be porous. The easy to empty plastic bag, for me, sort of negates the purpose of the trashcan separator.


If you are able to use the trashcan to your liking, then I'd just put a set of 1 micron bags on the outlet and be happy. You won't have to empty the lower bag much. If you put a canister on you may increase the airflow (that's part of the reason for doing so) and your trashcan may stop working. Or get a canister and forget the trashcan and the space it takes.

[Jeffrey Schronce]

i think in an earlier post you said you were going to use the trashcan separator. I think I said that some people find it works and some find it doesn't. I think the reason why it works and why it doesn't depend upon airflow and restriction - those with some restriction find the air flow is low enough it works and those with better flowing systems find it sucks all the stuff out of the can. Those who claim it works have sufficient air flow for their needs and are happy - so that's fine. Those with better air flow are probably happy, too. Those with restricted airflow that has caused problems such as plugged lines probably did something to fix it - maybe removed the trashcan.

so I don't know which camp you'll fall in.

My personal use has no trashcan separator, I have a HF 2HP DC, use a Grizzly canister/cartridge filter and a plastic bag on bottom. I'm about to empty the bag for the first time as the bag is more than half full and its seems like its sucking stuff out of the bag.

I personally like the canister system, it makes sense to this engineer.
The Wynn has been made available since I got mine - I'd go with the wynn if i had to do it over.

One of the 2 main reasons for the canister is to replace the bottom cloth filter bag with a plastic bag that's easy to empty. The canister has 7 times the area of a bag so the lower bag no longer needs to be porous. The easy to empty plastic bag, for me, sort of negates the purpose of the trashcan separator.


If you are able to use the trashcan to your liking, then I'd just put a set of 1 micron bags on the outlet and be happy. You won't have to empty the lower bag much. If you put a canister on you may increase the airflow (that's part of the reason for doing so) and your trashcan may stop working. Or get a canister and forget the trashcan and the space it takes.

Thanks.
I am not set on seperator and am pretty much talked out of it at this point.
Now for my brand new question . . .
The canister filter. You say it have better flow that dual 1 micron bags? Also, how do you maintain the filter? I have noted applications where there are handles on the top and you turn them and the dust falls to the bottom bag. This does not appear to be the case with the Wynn. So how do you clean it?

[LCHIEN]

Thanks.
I am not set on seperator and am pretty much talked out of it at this point.
Now for my brand new question . . .
The canister filter. You say it have better flow that dual 1 micron bags? Also, how do you maintain the filter? I have noted applications where there are handles on the top and you turn them and the dust falls to the bottom bag. This does not appear to be the case with the Wynn. So how do you clean it?

Yeah, the surface area of a pleated filter cansiter or cartridge runs from 7 to 20 times as much area as a bag. Depends on the density of the pleating. Too much pleating will allow the filter to clog with chips. So one pleated filter will replace two bags and still have much less total air flow restriction.

So maybe you pop it with a few bursts of air from the compressor and air gun. That knocks the small stuff off the inside of the filter and into the bottom bag. I have one of those with a handle and a beater. The pleats are stiff and running the beater around gives it a pop on every pleat. I have a neutral vane and all the ever falls off the top canister is fine dust.
(search the tool posts for Neutral vane if you don't know what that is.)

[Jeffrey Schronce]

Yeah, the surface area of a pleated filter cansiter or cartridge runs from 7 to 20 times as much area as a bag. Depends on the density of the pleating. Too much pleating will allow the filter to clog with chips. So one pleated filter will replace two bags and still have much less total air flow restriction.

So maybe you pop it with a few bursts of air from the compressor and air gun. That knocks the small stuff off the inside of the filter and into the bottom bag. I have one of those with a handle and a beater. The pleats are stiff and running the beater around gives it a pop on every pleat. I have a neutral vane and all the ever falls off the top canister is fine dust.
(search the tool posts for Neutral vane if you don't know what that is.)

Sorry if I am killing you here. So the Wynn filter is availiable with the handle and beater?