LumberJocks

Advice on venting upperbag dust outside the shop

  • Advertise with us

« back to Focus on the Workspace forum

Forum topic by Falegname posted 01-22-2016 04:31 AM 859 views 0 times favorited 23 replies Add to Favorites Watch
View Falegname's profile

Falegname

33 posts in 2409 days


01-22-2016 04:31 AM

Topic tags/keywords: dust control

Hello fellow Lumberjocks… I was recently given a dust collector similar to this one

http://www.busybeetools.com/products/dust-collector-1hp-570cfm-1-mic-bag-csa.html

I think it will meet my needs, but I’d like to vent it outside instead of through the upper bag. Has anyone done this successfully? I’m wondering if I will be destroying the dust collector or if it will still function at all without the back pressure from the upper bag. So far the only way I can think of doing this is to remove the upper bag and build some kind of reducer to get it down to a 4” pipe that I plan to put through the wall of my shop.

Any advice is welcome.

-- Mark / Montreal - "Measure Once, Curse Twice."


23 replies so far

View Fred Hargis's profile

Fred Hargis

3950 posts in 1961 days


#1 posted 01-22-2016 12:08 PM

What might happen if that venting will allow the unit to move more air. That may well overload the motor and burn it out. You can test this with an amp meter if you want to stay with that unit. Read the amps and compare the reading the FLA number on the motor plate. In all honesty, I would be surprised if your happy with the performance of that unit. The reducer for the exhaust can be as simple as a piece of plywood cut to fit the DC outlet, then put a 4” (+/-) hole in it to accept a PVC union, secure it with screws and seal it, then pipe your pipe into it.

-- Our village hasn't lost it's idiot, he was elected to congress.

View rwe2156's profile

rwe2156

2200 posts in 948 days


#2 posted 01-22-2016 12:08 PM

Fred,

I have vented my blower outside (cyclone) and it works great. I don’t understand how reducing the back pressure could overload the motor. I would think it would actually reduce the load. Please educate me! I talked to Jet before doing it and they said there would not be a problem.

Mark,

The only realisitic way I know of is to remove the motor/blower from the bag assembly, turn the unit on its side and add either a cyclone or some other separator. Then just attach a duct through to the outside.

But I totally agree with Fred, on a unit this small I think you’re wasting your time.

What are you using it for?

Keep in mind with venting outside you need replacement air which in Montreal is a critical consideration, depending on the size/cost of heating your shop.

My advice is to simply upgrade the filter to a canister, attach a small cyclone and use it as a mobile machine-to-machine collector.

-- Everything is a prototype thats why its one of a kind!!

View TheFridge's profile

TheFridge

5765 posts in 954 days


#3 posted 01-22-2016 12:30 PM

I took the collector and put it on a 55 gallon drum. I cut a thein baffle in the drum lid. I melted a Rubbermaid trash can lid to the top with a 4” plumbing 90 in the center, pointed away from the shop. I ran a piece of 5” plumbing pipe outside to the collector/ drum setup with the motor and impeller inside under my table saws extension table. It just spits chips into the yard when i forget to empty it.

Works like a champ.

Edit: lowering back pressure put less stress on the motor.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

View Fred Hargis's profile

Fred Hargis

3950 posts in 1961 days


#4 posted 01-22-2016 01:28 PM

Any thing that reduces the resistance to flow in a DC system will increase the amount of air that system can move…..hence reducing the back pressure on the discharge allows more air movement. That (more air), in turn, increases the load on the motor. Like I said, you can test this easily. You will see an increase amperage with an open discharge, it may not be enough to be a problem…but then again it might.

-- Our village hasn't lost it's idiot, he was elected to congress.

View TheFridge's profile

TheFridge

5765 posts in 954 days


#5 posted 01-22-2016 01:39 PM

Ehhh. Gonna have to disagree there bud. The increase in air flow is just the motor doing more work with less power. Because the airflow increases doesn’t mean the amperage does. The induction motor wants to run at or near its rated rpm. Any restrictions or added load will cause it to draw more power to try to keep up. If you ran an induction motor with no load at all it would run just fine.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

View Fred Hargis's profile

Fred Hargis

3950 posts in 1961 days


#6 posted 01-22-2016 01:53 PM

You couldn’t be more wrong, but I’ll leave it at that. You are correct that running it with no load is just fine, now adding air to the impeller adds load, hence more amps as the motor tries to overcome that load (and stay at it’s stated RPM). Reducing backpressure at the discharge allows it to add air (and load). But with that, I’m done…..

-- Our village hasn't lost it's idiot, he was elected to congress.

View TheFridge's profile

TheFridge

5765 posts in 954 days


#7 posted 01-22-2016 01:55 PM

Pretty much an electrician. 15 years. Just sayin.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

View ErnestP's profile

ErnestP

14 posts in 379 days


#8 posted 01-23-2016 01:52 AM

One thing to consider, with outside venting…
If your shop is a conditioned environment,
you’re pumping all that heat/cool air outside.

As for the rest, you can hook up a cyclone/chip catcher.
Pre-stage it to the blower/impeller.

First, pipe the shop collection to the outside, into a cyclone box.
Bring the cyclone exhaust back inside, into the blower section’s intake.
Let the bags do their job, as a final, fine-dust filter.

I’m assuming, your goal is easier maintenance/emptying.
Noise-reduction, you’re best option is an enclosure/closet
i.e. isolation of the motor/impellor assembly.

Ern

View clin's profile

clin

514 posts in 464 days


#9 posted 01-23-2016 04:19 AM

I think Fred is correct on this one. It’s not the motor, it’s the blower which is a form of centrifugal pump. Like a squirrel cage fan on your furnace. If you completely plug the supply (or exhaust) of air, the motor will completely unload. It can’t do any work if it isn’t moving air.

On the other hand, the more freely it can move the air, the more air it will move at a higher speed and therefore do more work loading the motor more. Of course motor characteristic are going to play a role. So it’s also not going to be as simple as an unrestricted blower is certain to overload the motor.

-- Clin

View Rick M's profile

Rick M

7935 posts in 1848 days


#10 posted 01-23-2016 12:28 PM

What I can tell you 100% from experience is that if you allow a fan designed to work with restriction, to pull more air than it should, the motor will overheat. The restriction on a DC should be on the inflow, not the outflow, so venting outdoors shouldn’t hurt the motor.

Back on topic, I know 2 guys who vent outdoors. I’ve been in both their shops during the winter and couldn’t feel a temperature change while the DC was running. The reason is that once everything (machines, floors, walls, etc.) in your shop is up to temperature, it will hold temperature even when some air is evacuated. It will be less energy efficient but not as bad as people theorize.

-- http://thewoodknack.blogspot.com/

View rwe2156's profile

rwe2156

2200 posts in 948 days


#11 posted 01-23-2016 12:39 PM

Rick M -

How big were their shops and how much was the DC running?

Depending on the size of the shop, how much the DC is running, and how cold it is outside, and how you heat the shop, it can be a problem.

-- Everything is a prototype thats why its one of a kind!!

View rwe2156's profile

rwe2156

2200 posts in 948 days


#12 posted 01-23-2016 12:45 PM



You couldn t be more wrong, but I ll leave it at that. You are correct that running it with no load is just fine, now adding air to the impeller adds load, hence more amps as the motor tries to overcome that load (and stay at it s stated RPM). Reducing backpressure at the discharge allows it to add air (and load). But with that, I m done…..

- Fred Hargis

I believe you but intuitively it doesn’t sound right. How can reducing the back pressure allow more air into the system? I would think the only load factor is on the inlet side.

I have no way of comparing filter vs. no filter on my unit, but I am going to put an ammeter on it just for my own info. It’s never tripped a breaker but I’m curious now. All I know is by venting outside the performance increaded dramatically.

-- Everything is a prototype thats why its one of a kind!!

View JeffP's profile

JeffP

573 posts in 859 days


#13 posted 01-23-2016 01:18 PM

That’s the cool thing about science. No need to “decide who to believe”. People have done testing of dust collectors with different amounts of air flow restriction and video taped the results.

YouTube overfloweth with examples of this. Mathaais Wandel of WoodGears has several videos that show current flow readings for same unit with different amounts of air-flow allowed.

Universally, a fan uses more energy when it is moving more air. Agreed, on the surface, it is counter-intuitive that removing an obstacle would increase the power consumption. You could look at it another way…all of physics is beholden to the laws of thermodynamics. One of those laws can be paraphrased as “there is no free lunch”. Moving more stuff requires more energy.

Pretty much a degreed Electrical Engineer for 30 years. Just sayin.

-- Last week I finally got my $*i# together. Unfortunately, it was in my shop, so I will probably never find it again.

View JeffP's profile

JeffP

573 posts in 859 days


#14 posted 01-23-2016 01:23 PM

Separate answer more specific to the OP question…

Many of us have our DC ported outside rather than filtering the air and sending it back to the shop. It is a very common thing to do. So far (knock on wood) I have never seen a posting here or elsewhere saying “I changed my DC to port outside and it broke right away”. Not saying it can’t happen or hasn’t happened…just saying it is a common thing to do and there is no evidence that it is particularly risky to the health of the DC.

One other point…if you’re putting a hole in the shop anyway, consider moving the whole unit outside rather than just porting it outside. Cuts down on the noise considerably.

-- Last week I finally got my $*i# together. Unfortunately, it was in my shop, so I will probably never find it again.

View tomsteve's profile

tomsteve

394 posts in 687 days


#15 posted 01-23-2016 02:00 PM

something else to consider venting outside is proximity to house. a friend of mine vented his outide. unfortunately he would get a dust coating on his vehicles, deck, and it even got into the house in the summer with all the windows open.
ened up venting into an enclosed trailer.

showing 1 through 15 of 23 replies

Have your say...

You must be signed in to reply.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics

HomeRefurbers.com