Dust extractor question

Hey folks.

I have a 3 HP 3 phase dust extractor that was
originally mounted on a table with a 6 foot
updraft pipe, a box and an elbow hooked to a 10
foot 'sock' which fits over a 55 gal. drum. All
the pipe is 8".

I am mounting the extractor in my shop approx 8
off of the floor and was considering ducting the
output through the shop wall into the great
outdoors.

Do these things need backpressure for some
reason?
Thoughts, comments?

Brad
a176615.jpg
 
It should not require any back pressure, just plug it in and measure motor amps with nothing connected, that will be maximum draw.
 
ok is your shop heated/cooled?
if so you want the unit to discharge inside the building thru some type of filter.
if you insist on venting it outside then you need a louver with enough opening to keep your building from going into negative air pressure. then you will want someway of heating/cooling this makeup air to room temp.
as to the unit itself needing back pressure it probably does. run the unit wide open long enough to get amp readings, if the amp reading is more than the motor rating then you need to restrict the air flow until the amp draw is correct. this can be done with restriction on the leaving side like originally done or restrict the incoming air to the fan.
good luck
Ron
 
If you exhaust it to the outside, you will need make up air. Unless you have elec heat or sealed combustion chamber you will pull the heaters exhaust fumes into the room--not good. You will also take all of your heated air and send it outside.
 
Industrial dust collectors almost always place the cyclone separators, collection bins, and air filters outside the building for easier cleaning and less contamination inside the building. If there are no hazardous fumes, most will filter the exhaust air and return it to the building to reduce the heating and air conditioning costs rather than dump all the exhaust outdoors.

If your building is heated, you may want to consult or hire an HVAC contractor to size up and install your system for you.
 
Almost all devices of this type work off of flow, so back pressure isn't the concern. The flow needs to be high enough to entrain the particulate and then drop enough to dis-entrain at the point of collection.

It appears to be a bag house so that sock may be the collection component. It sounds like you may be contemplating shortening the bag which could alter the configuration.
 
I use squirrel cage fans out of old furnaces as my shop AC. Yes some direct drive blowers will use excessive current without back pressure.

I use an ammprobe, a piece of wood and block off some of the output. The air speed picks up and the current goes down to a safe level. I have overheated some fan motors without back pressure.

So I would say a little back pressure won't hurt anything. Try it. Restricting the air going in to a fan is no good, it will increase current.
 
You are right. In 95 I had a conventional Nat furnace in my house and installed a gen-air range in house. The 1/3 hp exhaust fan on range would suck the exhaust from furnace down the chimney into the basement.

We had to open a window in kitchen if we wanted to use exhaust fan.
 
Brad,
50 years ago a man who made wood frames for sofas and chairs had a central vac system to put his sawdust in a hopper next to his steam boiler. He burned the sawdust to heat his building and dry his wood. He also had a wood chipper to chop up his scrap lumber.

A college in Terre Haute takes branches, chops them up and heats all their building with wood chips.

Something to think about.
george
 
READ WHAT I WROTE BEFORE SAYING IT IS UNTRUE
YOU ARE SETTING HIM UP TO OVERLOAD HIS MOTOR AND BURN IT UP
everything I wrote has been proved time and time again in the field.
that blower wheel motor combination is sized for a certain amount of restriction and will draw high amps if run wide open instead of as designed
 
Hey George.

The airstream coming out of this blower is enough to jerk your arm up when you hold your hand over it, kinda like sticking your hand out of the car window when you are doing 70.

I really would like to save the floorspace as much as anything else. I can run an 8" round duct about ten feet over the floor for about 30 feet right out the back wall nice and neat.

When I am planing lots of lumber I may look into collecting the chips somehow.

Brad
 
Hey Bill.

The yellow tower thing is actually a gadget that I welded together to house the components for my phase converter.

It operates at 575 volts and requires a large transformer and a three phase idler motor that weighs about 200 pounds.

The original sock just hung off the duct about 10 feet off the floor.

Brad
 
Hey ss.

Right now this shop is uninsulated and I usually use spot heating for mechanical jobs and am finishing a 14 x 24' climate controlled area inside the main shop.

If I heat the whole thing I will have to do something different with this system.

Brad
 
Brad, I made a chip collector for my 13 inch dewalt planner. Made it out of a large plastic drum, 4 inch metal clothes dryer flex pipe, a trash can with holes in it covered with aluminum window screen. Designed it like a bagless vac. Out the center of the trash can comes the very fine dust that can go through the window screen. The fine dust is discharged out the window.

One day a neighbor came over when I was using the planner. He saw the dust and thought it could be smoke.

If I remember, I'll post you some pics of my very simple design. Except for the flex pipe, everything was free recycled items.

I keep the large chips to put in the dumpster to dry things out or use on garage floor instead of oil dry.

If I had a fan as large and powerful as your, I would definately be designing a central vac to suck all the sawdust and planner chips into a hopper.

There is a sawmill about 40 miles away. They debark the logs before they cut them. They have a special room they blow the sawdust to and a second room they put very clean wood chips. Any scrap wood is chipped up.

They sell chips and sawdust $10/yard. People with horses buy sawdust. I buy the large chip for flower bed mulch. Last year I bought 12 yards of chips.
George
 
Hey EB.

Ya got me thinking.

Right now my shop is not insulated or heated save for spot heating .

The discussion about the backpressure has me intrigued.

I am currently doing a permanent installation on my phase converter (waiting for a 600v. 3 phase relay) and when I get it set up will check the amps with the inductive meter and report back.

Brad
 

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