Menu
What's new

Pentz design cyclone

Ok, I was confusing your setup with larry's, my bad. Shouldn't be any problem with the fan either. Definitely try emptying the saw dust bin. I know the manual for my grizzly said it will carry over sawdust if the drum is too full.
 
Jeb Taylor said:
Ok, I was confusing your setup with larry's, my bad. Shouldn't be any problem with the fan either. Definitely try emptying the saw dust bin. I know the manual for my grizzly said it will carry over sawdust if the drum is too full.
Click to expand...

I emptied the bin, its a 55 gal drum and it was about 10" from the top, It helped some, then I opened another blast gate since the sander is only hooked up with a 4" hose right now. That helped to the point where I couldn't see dust coming out of the blower but it still made the air cloudy somewhat. I guess that would be normal? I would think that having a longer ducting run before the cyclone and a smoother transition from the duct to cyclone would help further.
 
If I decided to exhaust the cyclone outside whats the best way to deal with makeup air. I have a propane heater that draws combustion air from inside and power vents outside, so I would need a solution that would not cause a problem with that.
 
Dave Black said:
If I decided to exhaust the cyclone outside whats the best way to deal with makeup air. I have a propane heater that draws combustion air from inside and power vents outside, so I would need a solution that would not cause a problem with that.
Click to expand...

With mine, my plan is to make it so it is switchable, inside to out. That is a lot of heat loss, if you calculate what 2000cfm say will cost you to heat in the winter you may want to change your mind. Depends on how much you actually run the DC, and your average temp, but there are days for me when it is on all day.

Larry
 
Larry Edgerton said:
With mine, my plan is to make it so it is switchable, inside to out. That is a lot of heat loss, if you calculate what 2000cfm say will cost you to heat in the winter you may want to change your mind. Depends on how much you actually run the DC, and your average temp, but there are days for me when it is on all day.

Larry
Click to expand...

That is why I vented inside in the first place, after having the cyclone for a few years I am now thinking it may not be too bad to vent outside. I think that I may do what your plan is a have it switchable. I can rig up a system so when I turn on my sander blastgate it will switch the air to vent outside.
 
Since I moved the shop into the basement a few weeks ago I got most of the tools set up and the DC ducting hooked up the them. I would like to put the cyclone and blower in the garage to cut down on noise and make it easier to empty the dust bin. To do this I would need to add about 15'-18' of ducting 2 90 degree turns and about the same amount of flex hvac duct to go from the blower to the filters. Any thoughts about how this would effect the performance?
 
What's your total ft of ducting/sizes you're running? Do you happen to have a fan curve for your fan?

I have a feeling you're going to get a very significant impact in your dust collector adding that much. The 90's are equivalent to about 12' duct each, and flex is usually listed as being equivalent to 3x as much rigid duct.


It's hard to give you any real specifics without knowing the fan curve/duct layouts, but you might be looking at as much as 3-4" pressure difference to maintain 3500-4000 fpm air speed. If your air speed drops off to much because of the extra flow resistance, you might run into trouble keeping the sawdust clear, as well as decreased dust collecting performance.
 
Jeb Taylor said:
What's your total ft of ducting/sizes you're running? Do you happen to have a fan curve for your fan?

I have a feeling you're going to get a very significant impact in your dust collector adding that much. The 90's are equivalent to about 12' duct each, and flex is usually listed as being equivalent to 3x as much rigid duct.


It's hard to give you any real specifics without knowing the fan curve/duct layouts, but you might be looking at as much as 3-4" pressure difference to maintain 3500-4000 fpm air speed. If your air speed drops off to much because of the extra flow resistance, you might run into trouble keeping the sawdust clear, as well as decreased dust collecting performance.
Click to expand...

I couldn't find a fan curve for my blower, its a 5hp, 14" impeller pentz design. My other thought was to put the cyclone in the basement and the blower in the garage, This would eliminate the 90's and not really add any duct. I am using 6" PVC duct. The main duct run is about 25' and with fairly short branch lines.
 
There's a pretty huge difference between a 14" and 15" impellar, you're in a lot better shape than I thought. 6" pipe should have your fan in the low flow region of the fan curve, so you're probably getting very high velocities right now. Without running all the numbers, I'd say you're good to add an equivalent of 50-75' of 6" pipe without going below 800 cfm range. Pentz has an excel sheet on his page, and www.airhand.com has a good quick and easy design guide to approximate flow rates with the changes. It would be best to avoid pvc 90's though, if you can get some metal sweeping 90's that are close to the same ID as your pvc it would be nice. Not sure what schedule pvc you have though.


I'm not real sure how the flex hose you're talking about is going to perform, it'd be best to try and avoid adding 15' of flex going to the filters. You might be ok if you oversized it a lot, it would reduce the pressure drop from that hose. It'll be prone to get dust build up in it, but if it's operating correctly you should be getting very little carryover. So depending on how easy it is to get to, running some 8" or bigger hose there might be a trade off - clean occasionally, but better performance from the dust collector. If you can relocate it some way to get rid of that 15' of flex it would really be worthwhile though.
 
Jeb Taylor said:
There's a pretty huge difference between a 14" and 15" impellar, you're in a lot better shape than I thought. 6" pipe should have your fan in the low flow region of the fan curve, so you're probably getting very high velocities right now. Without running all the numbers, I'd say you're good to add an equivalent of 50-75' of 6" pipe without going below 800 cfm range. Pentz has an excel sheet on his page, and www.airhand.com has a good quick and easy design guide to approximate flow rates with the changes. It would be best to avoid pvc 90's though, if you can get some metal sweeping 90's that are close to the same ID as your pvc it would be nice. Not sure what schedule pvc you have though.


I'm not real sure how the flex hose you're talking about is going to perform, it'd be best to try and avoid adding 15' of flex going to the filters. You might be ok if you oversized it a lot, it would reduce the pressure drop from that hose. It'll be prone to get dust build up in it, but if it's operating correctly you should be getting very little carryover. So depending on how easy it is to get to, running some 8" or bigger hose there might be a trade off - clean occasionally, but better performance from the dust collector. If you can relocate it some way to get rid of that 15' of flex it would really be worthwhile though.
Click to expand...

I use 6" S and D PVC which is thin wall used mainly for outdoor drainage, I wasn't going to use elbows, I will use 2 45's with a short piece in between. I was planning on using 8" or 9" insulated HVAC flex from the blower to the filters. Somewhere on Bill Pentz's site he said using HVAC flex works well as a muffler. I used about 8' of 8" HVAC flex when I was in the other shop. The flex didn't seem to get dust buildup, When I installed it I stretched the flex as much as possible to avoid getting bumps between the wire reinforcement, seemed to work well.
 
I'm going off the assumption you're running around 900 cfm in your ducting, if you have 6" hole worth of openings on your duct at any point in time, which would be ideal for 6" duct.

A metal duct path 15' long is going to add around .2" water in 8", or .834" water in 6" With flex hose, I'm sure there's a huge variation depending on the type, but the rule of thumb I've always read is 3x ducting pressure drop for flex hose. So you're adding about .6" water static pressure with the 8" flex, which isn't bad, or 2.5" water with 6" flex which is pretty considerable for just connecting your filters.

Now the downside of the 8" is you're only moving around 2500 fpm which is well under the speeds to move dust that most dust colleciton/transport information recommend to move 100% of the dust. So you'll get some acculation. I know for my cyclone I haven't gotten a tablespoon of dust this year, so even if it was in the ducting I wouldn't notice. If you fill up your drum, you're going to be cleaning some ducting I would guess. Shouldn't be bad in normal operation.

You might be a little off 900 cfm, to really calculate it goes through an interative process, guess a flow rate, figure a pressure drop, check the curve to get the flow rate at that pressure, plug it back in etc until the assumed flow rate is close enough to the calculated flow rate. I think the results will be pretty close to the same though. I'd recommend reading through the pentz's stuff and/or the airhand.com design guide if you are interested in the exact impact on your system.

The 90's from www.blastgateco.com or www.oneida.com will probably work inside that pipe, google said it was 6-1/8" ID. I used the blastgate company's 90's slid inside spiral pipe and have had no problems with them. hand pland shavings, planer shavings, etc no troubles yet. They'll be a little loose so you'll have an edge inside, but the radius is a lot better.
 
Last edited:
Jeb Taylor said:
I'm going off the assumption you're running around 900 cfm in your ducting, if you have 6" hole worth of openings on your duct at any point in time, which would be ideal for 6" duct.

A metal duct path 15' long is going to add around .2" water in 8", or .834" water in 6" With flex hose, I'm sure there's a huge variation depending on the type, but the rule of thumb I've always read is 3x ducting pressure drop for flex hose. So you're adding about .6" water static pressure with the 8" flex, which isn't bad, or 2.5" water with 6" flex which is pretty considerable for just connecting your filters.

Now the downside of the 8" is you're only moving around 2500 fpm which is well under the speeds to move dust that most dust colleciton/transport information recommend to move 100% of the dust. So you'll get some acculation. I know for my cyclone I haven't gotten a tablespoon of dust this year, so even if it was in the ducting I wouldn't notice. If you fill up your drum, you're going to be cleaning some ducting I would guess. Shouldn't be bad in normal operation.

You might be a little off 900 cfm, to really calculate it goes through an interative process, guess a flow rate, figure a pressure drop, check the curve to get the flow rate at that pressure, plug it back in etc until the assumed flow rate is close enough to the calculated flow rate. I think the results will be pretty close to the same though. I'd recommend reading through the pentz's stuff and/or the airhand.com design guide if you are interested in the exact impact on your system.

The 90's from www.blastgateco.com or www.oneida.com will probably work inside that pipe, google said it was 6-1/8" ID. I used the blastgate company's 90's slid inside spiral pipe and have had no problems with them. hand pland shavings, planer shavings, etc no troubles yet. They'll be a little loose so you'll have an edge inside, but the radius is a lot better.
Click to expand...

I'm going to do a noise comparison with the blower in the garage then in the basement. If theres not much difference in noise in the house then it will probably go in the basement, but I think it would be quieter in the garage. I looked at the fan curve and static pressures for both ways and I should be fine either way, but keeping the blower and cyclone or at least the cyclone in the basement would give me excellent performance,
 
I did a noise comparison and the house is much quieter with the blower in the garage so its going out there. I was thinking about keeping the cyclone body in the basement so that the main trunk line could just go into straight into the cyclone. I looked at doing this today and I realized that to do it I would have to cut a 10" hole in a floor joist as well as through the band joist or header joist ( not sure what the right name is, its the joist that sits on the concrete basement wall and runs parallel to the other joists) I don't think the band joist would be a problem since the joist is fully supported the whole length, but I think there would be problems cutting the other joist. If I mount the blower and cyclone in the garage I would only have to cut a hole in the band joist. Heres some pics, 1 of the basement corner, you can see the 6" duct in picture, The other 2 are pics of the garage, the duct would come out of the bottom of the wall to the right of the door and I would put the cyclone a few feet left of the door. Would long sweep 90's be better than regular 45's to make the turns to the cyclone?
 

Attachments

  • DSCF2021.jpg
    DSCF2021.jpg
    126.6 KB · Views: 25
  • DSCF2020.jpg
    DSCF2020.jpg
    104.8 KB · Views: 20
  • DSCF2018.jpg
    DSCF2018.jpg
    52.2 KB · Views: 17
That is not a good idea to cut thru the board. Cutting a joist is something that can be carred by running a few extra peices, but the the outside board should stay solid.
 
You must log in or register to reply here.
Top