getting ready to build

[bridger]

My starting point:

blue barrel. HF 2hp collector upgraded with felt bags. 4" S&D ducts.

I'm thinking to use the cart platform, build a simple cabinet on it to house the barrel, mount the blower/motor above the barrel bolted to the inside of the cabinet and couple the blower directly to the intake for the bags. I'm also thinking to couple the blower directly to the lid of the separator, with the baffle and spin chamber built right into the cabinet, rather than suspending the baffle down into the barrel and using the top portion of the can for the spin chamber. (more barrel capacity and easier emptying)

I have it all dimensioned out so it works, but I do have to figure out the connection between the separator and the barrel. the barrel will have to lift up and seal to the separator, be lowered to remove and empty it.

I get about a 19" diameter spin chamber. I'm figuring side inlet at 4", top outlet at 5". the inlet to the blower will stick down about 3/4" into the spin chamber if I mount it directly to the top of the spin chamber.

some questions:

what is the ideal height of the spin chamber? most of the pictures seem to show the distance between the baffle and the lid at about 1-1/2 to 2 times the diameter of the inlet pipe. has any work been done with taller spin chambers? I have plenty of height to work with.

is coupling the spin chamber directly to the blower a bad idea? I see pictures of blower over spin chamber generally coupled with a foot or 3 of pipe.

any thoughts as to whether to have the spin chamber rotation the same as or counter to it, and what a longer pipe between might play on that relationship?

[servant74]

Sounds like a good design. ... Below the baffle I don't think the shape makes much difference, your box containing your barrel just must be 'sealed' so as to not leak vacuum. 

I have thought about making a similar setup, and either need to make the baffle a little smaller than the diameter of the barrel, or put a short 'funnel' below the baffle to help ensure all the chips fall into the barrel rather than 'around' it.

...
some questions:

what is the ideal height of the spin chamber? most of the pictures seem to show the distance between the baffle and the lid at about 1-1/2 to 2 times the diameter of the inlet pipe. has any work been done with taller spin chambers? I have plenty of height to work with.

From my understanding the ideal height of the spin chamber is just enough to allow the fittings between the 'top' and the baffle.

is coupling the spin chamber directly to the blower a bad idea? I see pictures of blower over spin chamber generally coupled with a foot or 3 of pipe.

Coupling the spin chamber top directly to the blower is not bad (good in my thought... for the most part reducing the friction by reducing the length of the ducting).  But you might consider extending the blower inlet down into the chamber to about half way to the baffle.  Extend it by enough to make the cross section (in sq inches) of the duct close to the area of the diameter of the ducting times the length between the duct and the baffle.  A little more open area is OK, but probably not having it open all the way from the top to the baffle.

The 3 ft or so of 'extra' pipe seems to be overkill to keep from cutting the pipe.  Hopefully someone else could chime in on that part.

any thoughts as to whether to have the spin chamber rotation the same as or counter to it, and what a longer pipe between might play on that relationship?

Making them in the same direction would seem to keep the efficiency higher.  Whenever air changes direction, any energy in it must be dissipated before it can start swirling in the other direction.  (If you want to be 'retentive' about it, look at the way the toilet swirls in your hemisphere and make it go the same way.  Countering that will work, but it adds yet another 'little bit' of friction counteracting the 'natural' swirl motion educed by the earths rotation.).

Also having the area of the input ducting to be similar to the area of the exhaust (to the fan) ducting should help ... This part is a guess, but it seems to make sense to me.

Does all this make sense?

[bridger]

Sounds like a good design. ... Below the baffle I don't think the shape makes much difference, your box containing your barrel just must be 'sealed' so as to not leak vacuum. 

the barrel isn't in a sealed chamber. the seal is between the rim of the barrel and the bottom of the swirl chamber.

I have thought about making a similar setup, and either need to make the baffle a little smaller than the diameter of the barrel, or put a short 'funnel' below the baffle to help ensure all the chips fall into the barrel rather than 'around' it.

I didn't consider a funnel. I want to seal the barrel to the bottom of the swirl chamber, so I don't think I have room for a funnel.

...
some questions:

what is the ideal height of the spin chamber? most of the pictures seem to show the distance between the baffle and the lid at about 1-1/2 to 2 times the diameter of the inlet pipe. has any work been done with taller spin chambers? I have plenty of height to work with.

From my understanding the ideal height of the spin chamber is just enough to allow the fittings between the 'top' and the baffle.

so with a side inlet design the swirl chamber could be as high as the diameter of the inlet duct- in this case 4". is there any feedback on units built that tightly?

is coupling the spin chamber directly to the blower a bad idea? I see pictures of blower over spin chamber generally coupled with a foot or 3 of pipe.

Coupling the spin chamber top directly to the blower is not bad (good in my thought... for the most part reducing the friction by reducing the length of the ducting).  But you might consider extending the blower inlet down into the chamber to about half way to the baffle.  Extend it by enough to make the cross section (in sq inches) of the duct close to the area of the diameter of the ducting times the length between the duct and the baffle.  A little more open area is OK, but probably not having it open all the way from the top to the baffle.

The 3 ft or so of 'extra' pipe seems to be overkill to keep from cutting the pipe.  Hopefully someone else could chime in on that part.

any thoughts as to whether to have the spin chamber rotation the same as or counter to it, and what a longer pipe between might play on that relationship?

Making them in the same direction would seem to keep the efficiency higher.  Whenever air changes direction, any energy in it must be dissipated before it can start swirling in the other direction.  (If you want to be 'retentive' about it, look at the way the toilet swirls in your hemisphere and make it go the same way.

that's not being anal retentive. that's just being uninformed.

Countering that will work, but it adds yet another 'little bit' of friction counteracting the 'natural' swirl motion educed by the earths rotation.).

it seems counter-intuitive to reverse the direction. however, if what allows the dust to settle out is the fact that the swirling air slows down and migrates to the center, reversing the rotation as it enters the blower might bump that process up a bit. or it might just rob horsepower. I don't know.

Also having the area of the input ducting to be similar to the area of the exhaust (to the fan) ducting should help ... This part is a guess, but it seems to make sense to me.

Does all this make sense?

it does make sense. however, my ducts are 4", and the inlet to the blower is 5". I'm going with it, unless I know that there is a benefit to adding an adapter, which I doubt.

[bridger]

I'm getting the impression that having a spin chamber the size of the inlet duct (side inlet design) is no problem- that extra height above is room to fit an elbow (top inlet design) and that room below is to pass chips between the elbow and the baffle (top inlet design). I haven't seen any units built with the same distance between the top and baffle as the inlet pipe size though. for instance, with a narrow chamber like that would it be beneficial to increase the diameter?

[phil (admin)]

I'm getting the impression that having a spin chamber the size of the inlet duct (side inlet design) is no problem- that extra height above is room to fit an elbow (top inlet design) and that room below is to pass chips between the elbow and the baffle (top inlet design). I haven't seen any units built with the same distance between the top and baffle as the inlet pipe size though. for instance, with a narrow chamber like that would it be beneficial to increase the diameter?

Having the inlet an inch or two below the top, and an inch or two above the baffle is the typical way to go.  It prevents debris from getting lodged in crevices and also improves airflow by decreasing resistance.

[bridger]

I'm getting the impression that having a spin chamber the size of the inlet duct (side inlet design) is no problem- that extra height above is room to fit an elbow (top inlet design) and that room below is to pass chips between the elbow and the baffle (top inlet design). I haven't seen any units built with the same distance between the top and baffle as the inlet pipe size though. for instance, with a narrow chamber like that would it be beneficial to increase the diameter?

Having the inlet an inch or two below the top, and an inch or two above the baffle is the typical way to go.  It prevents debris from getting lodged in crevices and also improves airflow by decreasing resistance.

in the case of a side inlet system there aren't so many crevices to worry about. if maximum velocity of the swirling air is the goal I'd think that having the chamber the same vertical size as the inlet pipe would be ideal- but I don't know how diameter plays into that scenario. now if the inlet pipe were to project into the chamber a bit that clearance above and below might be needed. is any information about the benefits of having the inlet pipe flush versus projecting into the chamber available?


thanks
Bridger