DC in a box, exhaust air?

[kerrybp]

Hi all,

I'm trying to design a DC system using my Delta 50-850, top-hat style separator using the drum from the 50-850, and Wynn filter (still to be purchased).  Ideally, I'd like to put all of it in a sound-insulating enclosure on wheels that will take up as little space in my half of the 2 car garage as possible (floor space especially, but also vertical, as I could place it under a lumber rack if it's short enough).  I know that having it in an enclosure could be bad for overheating the motor, so I thought to place a vent near the motor but opposite of the cartridge filter so the filtered air would pass across the motor to cool it.  Has anyone tried something like this or have any concerns about the idea?

My second question is about the air after it leaves the blower and goes to the filter.  If I made some sort of a box between the blower and filter instead of using flex pipe, I could use the narrower Wynn filters and not have a tight corner.  If the volume of the box was large enough (not sure what "large enough" is yet), would the air flow at that point matter, or would it just be depressurized air?  And, does the shape of the interior of that box matter - should I make it rounded in some direction?

Finally, if I remove the restrictor ring in the 50-850 and only connect to a single machine via 6" flex pipe, would I risk damaging the motor with the configuration I've described?

Thanks for the help in advance!

[retired2]

I don't like option two.  The box between the blower and filter doesn't do much other than create a lot of turbulance, back-pressure, and consequently more noise.  It really doesn't matter how big the box or what the shape, because it still has a round pipe going in (6"?) and a round outlet to the filter.  You are better off with the smooth round bend of the pipe in figure one.

Before you invest any time and material building a box, I would test your configuration.  I don't know what the inside of the 50-850 separator ring looks like or how you have the blower attached to it, but I just have a feeling you are going to have a lot of waste by-pass.

If the configuration works as well as you hoped, then add the filter and build the box.  Don"t expect miracles from a small light box.  All that air has to get out of the box and if you size the vent to avoid putting back-pressure on the system, you are going to let a lot of noise escape.

[dabullseye]

theses are early pic rt after i built my top hat.motor and tophat are on one side of door and my 50-850 ring and filter/bag are enclosed in a cabinet on other side of door the top of cabinet is open. since then ive added a screw jack under can and some pink foam around motor/tophat supports plus i moved my framed decimal chart in front of motor/TH now its really quiet. having the filter/bag in the cabinet is no big deal over the yrs i only have a tiny amount of dust in bag(maybe a quart)my 50-850 frame is elevated on platform and panels are on z clips. when i built it i put french cleats on outside of panels but ive never used them cuz that corner of shop is buried behind in junk

[retired2]

theses are early pic rt after i built my top hat.motor and tophat are on one side of door and my 50-850 ring and filter/bag are enclosed in a cabinet on other side of door the top of cabinet is open. since then ive added a screw jack under can and some pink foam around motor/tophat supports plus i moved my framed decimal chart in front of motor/TH now its really quiet. having the filter/bag in the cabinet is no big deal over the yrs i only have a tiny amount of dust in bag(maybe a quart)my 50-850 frame is elevated on platform and panels are on z clips. when i built it i put french cleats on outside of panels but ive never used them cuz that corner of shop is buried behind in junk

It appears you are using a self-built Thien as the first stage separator, and the 50-850 ring as the second stage.  However, the OP's sketches suggest he plans to use the Delta ring as the only separator.  I don't know what the inside of that ring looks like or how he plans to connect the blower to the ring, but I'm concerned about how well this configuration is going to separate the waste.  Since you are familiar witj the internals of the 850 ring, you might have a better idea.

[dabullseye]

kerry id build a top like retired2 top had design. use that as a first stage and then run that blower outlet to the delta 850 ring. i also installed a Thien baffle in my ring. on the top side of ring i turned on lathe a huge tapered plug to fit into ring so filter would have a place to seal. i think a made the center hole 7" and extended it down below the original opening so i ended up around 2" above baffle. check out this
http://www.jpthien.com/smf/index.php?topic=100.msg500#msg500
http://www.jpthien.com/smf/index.php?topic=164.msg1025#msg1025

[kerrybp]

Thanks for the replies and ideas. 

My intent on attaching the blower would be to close off the 11" opening in the inverted cone inside the delta ring, then use a 6" duct straight up to the blower inlet, much like TX_Lenador did in http://www.jpthien.com/smf/index.php?topic=1054.0 .  I'm not sure how that cone would affect the airflow or separation, though I recall Phil saying that people have had good success using the dc ring as a top-hat.

I'm not opposed to making a separate Thien top-hat, but I thought if the delta ring worked as well as a self-made top-hat, it would be a lot less work - already have the 6" side inlet and 20" diameter cylinder, just need to cut some circles.

I'd like to keep the airflow as high as possible, so having two rings (a Thien top-hat and the delta ring) seems like it would restrict flow.  If I can get rid of one of those and go directly into the filter, that seems better to me for airflow.  The only caveat would be if the air forced into the filter slams into the bottom of the filter and creates turbulence.  I don't know if that happens or not, but the design seems to work fine with cyclone systems.

The enclosure I had imagined is made of 2x4s with insulation between, peg-board (rough side exposed) to the inside and something (homasote, maybe) on the outside.  To keep it from back-pressuring the system, is there a rule-of-thumb for sizing the vent?  I agree that if the vent has to be large, it defeats the purpose of the box.

dabullseye, I had the same thought about putting french cleats on the enclosure.  I try to make things do double duty in my garage if possible.

[retired2]

There's no rule of thumb for the vent size, but the larger it is the lower the velocity will be - that's good thing, but the larger it is the more noise that will escape - that's a bad thing! So, it is a bit of a balancing act.   I think a minimum size would be the size of the inlet to your bag filter.

[jdon]

Finally, if I remove the restrictor ring in the 50-850 and only connect to a single machine via 6" flex pipe, would I risk damaging the motor with the configuration I've described?

I think it's safe to remove the restrictor ring. I assume you're referring to the sheet metal disc that's spot welded just to the inside of the impeller intake, which reduces the intake diameter. I removed the ring in a 50-850 that I had, by drilling out the welds, and had no problems.

It's my understanding that the ring was added in later versions of the 50-850, as a means to prevent possible motor burnout resulting from numbskull user behavior. By that I mean running the DC with no duct work attached, and possibly without a filter. With no restriction to air flow, the motor will move a lot of air, and draw a lot of amps- so risk burning out. The restrictor prevents unimpeded air flow, but also impairs performance.

As long as you have a filter and a duct attached to your DC, you should have enough restriction that motor burnout isn't an issue, and the restrictor ring isn't needed, or even desirable.

[jgt1942]

kerrybp - your design is something like mine, see the following image.
One of my first attempts was to install the Thien ring (e.g. the ring in the bottom of the Thien baffle) in the Grizzly intake. I was NOT satisfied with the results. After picking up a lot of dust I removed the intake hose and there was a LOT of dust on top of the ring.

Thus I highly suggest NOT using the original ring and replace it with a Thien Baffle, use the design by Retired2.

As you can see my original design is portable and I've decided this was NOT a good option and a royal pain moving it around the garage and connecting to the tool being used. Thus I'm in the process of running fixed pipes and putting the DC in a corner of my garage.

Another major change I'm considering is eliminating everything on the left side of my image and just running the exhaust outside. I will be running my pipes to the DC and tools up in my attic just to get the pipes out of the way. From the output of my current blower, currently going to the bags on the left side of the image, I'm planning to just run it directly outside. Before I run it outside I will test the noise level to ensure I don't get my neighbors or the Home Owners Association upset with me. If the noise level is too high then I will do something like what I currently have or a Wynn filter as you are thinking.

The only time I get something in the bags is when the Brute can overflows. This can be resolved by either ensuring it is not full or installing an automatic shutoff. I'm thinking of installing the automatic shutoff. If you are running a lot of wood through a plainer you will be shocked as to how quickly the can fills. 

BTW I use a 20 GAL Brute, originally I planned to use the 32 GAL but this gets heavy for us old folks and if it is full dust it really blows up a cloud when emptying it into something else.

Put a lift under the can to lift it up to make a tight seal (I use door weather stripping) between the can and the Thien Tophat.
REF:

I know that having it in an enclosure could be bad for overheating the motor

You will be very surprised as to how much air the unit needs. I enclosed my air compressor in an area about 3x3x10 and installed a vent and fan to ensure it did not get too hot after using it quite a bit one day without the vent. The fan comes on when the air compressor comes on. Do the same for your enclosed unit.
REF:

I'm not opposed to making a separate Thien top-hat, but I thought if the delta ring worked as well as a self-made top-hat, it would be a lot less work - already have the 6" side inlet and 20" diameter cylinder, just need to cut some circles.

In my test the ring did not work near as good as the TopHat. I suggest going with the TopHat. The TopHat does NOT restrict the air flow and the amount of dust separation is VERY good.

[retired2]

I suggest going with the TopHat. The TopHat does NOT restrict the air flow and the amount of dust separation is VERY good.

Not true!  A top hat, at least mine, imposes a CFM penalty in the vicinity of 40%.  The exact figure can be found in the table of test data I posted on my build.

[jgt1942]

I missed your post on the air restriction and I was basing my statement only on observation of my unit which did NOT include   measurements with instruments. Thanks for the correction!
I looked for the gov. site with the measurements on the Tophat and cyclone and so far I have not found it. I found it very interesting at the time and I'm surprised I did not keep a copy of the report. The report was very well done, I do recall that both the TopHat and Cyclone had a dust separation in the high 90 percent range.

[BernardNaish]

That report sounds interesting and I would very much like to read it. Can anyone point to it?

BTW the link to r2's build is here:

http://www.jpthien.com/smf/index.php?topic=563.msg3034;topicseen#msg3034

[retired2]

I missed your post on the air restriction and I was basing my statement only on observation of my unit which did NOT include   measurements with instruments. Thanks for the correction!
I looked for the gov. site with the measurements on the Tophat and cyclone and so far I have not found it. I found it very interesting at the time and I'm surprised I did not keep a copy of the report. The report was very well done, I do recall that both the TopHat and Cyclone had a dust separation in the high 90 percent range.

The devil is always in the details!  The statement you are referencing probably included a qualifier such as "90% of all particles above x microns in size."  That is not inconsistent with a statement that also says they only capture a very small percent of the particles below x microns in size!

[jgt1942]

The devil is always in the details!  The statement you are referencing probably included a qualifier such as "90% of all particles above x microns in size."  That is not inconsistent with a statement that also says they only capture a very small percent of the particles below x microns in size!

It is driving me nuts that I cannot find the article I do recall that the author was very interested in the performance and even tested connecting the two devices in series. Hopefully I or somebody can find the website and article.

[kerrybp]

Thanks everyone for the inputs.  After doing a bit more reading about what makes a good top-hat design, I'm becoming convinced that I shouldn't use the dc ring - mostly because of the 6" round inlet that would be blowing in only 1" away from the 6" outlet, making bypass much more likely.

So, my plans now include making a top-hat with a 6" round to 8"x4" transition (13% larger cross-section for the rectangle).  I would make the rectangle taller and narrower, but that would increase the height.

I'd like to have the outlet at least even with the bottom of the inlet, so the tophat should be 11-12" tall.  With a 1.5H tophat, I recall some issues with bellmouth outlets (Mike F http://www.jpthien.com/smf/index.php?topic=1110.msg6292#msg6292), so I'm leaning toward a straight outlet with air-straighteners (t8/t12 bulb protectors).

I see that Retired2's tophat is 1H.  Is there any evidence that other than height, there is any drawback to making the tophat taller than the inlet?  I guess if I wanted to make the rectangle of my transition taller and narrower, I could make the overall height the same or slightly taller than the inlet.  I wonder which would be better...a 12" TH with an 8"x4" inlet or a 10" TH with a 10"x3.2" inlet?

As far as enclosing everything for noise-reduction, I'm going to try it without enclosure first and see how tolerable it is (I haven't had DC before, just recently picked up the used delta unit).  I may try an insulated hvac duct from the blower to the filter for the first step in noise reduction.

You will be very surprised as to how much air the unit needs. I enclosed my air compressor in an area about 3x3x10 and installed a vent and fan to ensure it did not get too hot after using it quite a bit one day without the vent. The fan comes on when the air compressor comes on. Do the same for your enclosed unit.

If I do end up enclosing, this was my concern.  However, the case of an air compressor vs a DC is a bit different, since the DC pulls ambient air into the box and if it flows across the motor, it should act like a very strong fan (or so my theory goes).  We'll see if I ever test that theory.

Thanks again for the ideas and thoughts... this site makes for some interesting reading on a topic I've never thought much about before.