Suffocation by DC

[Eduard Nemirovsky]

I am running 2 hp DC cyclone with air going out from the shop. Shop is airtight enough that if I am running DC it is difficult to open door. Usually I crack open sliding windows to keep air coming to shop. Now is very humid outside:(:( and I don't want to introduce humidity to the shop. If I am going to run DC with closed windows or door - will I "suffocate":confused::confused: my dust collection, would I have enough air flow?

[Rod Sheridan]

Hi Eduard, probably not.

If you notice the pressure diferential on the door, you're starving it for air.............Rod

[Lee Schierer]

You won't suffocate, a dust collector can't pull enough vacuum to do that. It will tend to run hot as it is cavitating the impeller and working inefficiently. You might want to rethink the outside air exhaust this time of the year.

[glenn bradley]

If it is hard to open the door, you need more air flowing into the room. If it is creating that kind of vacuum, it is not able to work optimally. JMHO.

[Aaron Rowland]

The motor will run cooler not hotter because it is doing less work, ie pumping less air. Only liquids cavitate. Airplane props get wear from dust particles but flying though rain will cause cavitation erosion. Starving the impeller for air by leaving a blast gate partially closed hurts nothing but dust pickup. One can measure the amp draw with a wide open gate. No contest, closed reduces amps meaning less work and less heat.

The one huge advantage of using a filter is no out side air comes into the shop. That's actually bad because the filter , even the best, does not catch the super fine particles, which are the biggest health threat. Out side air coming in results in air exchange with fresh air and that's good. Some people use both filters and some fresh air coming in.

I exhaust out side and have to use a dehumidifier this time of the year. I'm a hobby guy and my DC runs only a hour or two while working 6-8 hours in the shop. Cutting is fast. Sanding and assembly is slow for me. For sanding I do use filters on vacs with cyclones. Oneida's Dust Deputy does a great job as an add on to a Shop Vac Please buy one. $39 bucks at Amazon if you check around. I also use a Dyson module with a vacuum that has 14 each separate cyclones for fine sanding only. It gets it all.

I suggest adding an air inlet vent to your shop with a blast gate to vary the air inlet and buying a dehumidifier. One square foot of area should work. More is better. I hope you do not have a open furnace or water heater that reverse flows into your shop. Carbon monoxide.

[Dan Friedrichs]

You won't harm anything, but not having enough make-up air available results in much poorer dust collection by not being able to move any air. You need to either open a door/window, or exhaust through a filter inside.

[Dan Hintz]

I suggest adding an air inlet vent to your shop with a blast gate to vary the air inlet and buying a dehumidifier.
A word of warning if you go this route, Eduard... the size of dehumidifier you would need to actively remove moisture from the amount of air your DC will be exchanging every minute would be the size of your entire workshop. We're talking about replacing the entire volume of air in your shop every couple of minutes, and I'm sure when you look at it like that you'll realize your tiny little dehumidifer couldn't hope to keep up with that volume. Figure on several hours, at least, to properly dehumidify a room of any size, and you're swapping dry air with humid in a few minutes.

[Aaron Rowland]

A word of warning if you go this route, Eduard... the size of dehumidifier you would need to actively remove moisture from the amount of air your DC will be exchanging every minute would be the size of your entire workshop. We're talking about replacing the entire volume of air in your shop every couple of minutes, and I'm sure when you look at it like that you'll realize your tiny little dehumidifer couldn't hope to keep up with that volume. Figure on several hours, at least, to properly dehumidify a room of any size, and you're swapping dry air with humid in a few minutes.

================================================== ==============

As I tried to explain it depends on how much time the DC is on. Put the humidifier out side and try to reduce the humidiy in Iowa not a good idea. Put in in the shop and run the DC a few hours a day - no problem at all. Same deal in the winter. Every one worries about heat loss and trying to heat the shop. No problem again because air contains very little heat compare to hard objects like iron etc. I'm pumping 3 times or more air then Eudard per minute yet my humidly in the shop stays at about 40%. Today I think maybe the Cyclone was only for less then a hour , on and off. And I was busy sanding and gluing.

If you a pro and run your DC for 8 hours the shops around here do not have AC and the doors are open just like it was 50 years ago. Not my idea of fun however. For pros Regulations say no cyclone filters in the shop I think. I think small shops are exempt.

From what I see most hobby guys do not exhaust out side.That just not for me but not a criticism of those who have filters. I don't even know if you can buy a cyclone with out a filter.

[Alan Schaffter]

Well someone has finally done some homework.

Remember folks, you are not exchanging all the shop air, only a part of it- it may be the same part many times over- depends on the location/source(s) of take-up air. One solution to the negatives of discharging outside is to provide a source of take-up air at each machine. That will limit the amount of shop air exchanged- reduce heat/cooling losses and limit the increase in shop humidity. You may not like the idea of a separate duct or opening the nearest window, but that's what is required.

[Keith Avery]

Dan is definitely right about it being a total waste using a dehumidifier(while in the shop) if you are exhausting your dust collection. A 20 by 20 by 8 shop has about 3200 cubic feet of air in it. A typical DC will circulate that in 3-4 minutes. The summer here in middle TN is usually 90+ degrees and 80+ humidity. Air holds about .002 lb/ft3 of water in these conditions. So in about 3 minutes running your DC you are adding about 6.8 lbs or roughly 3 quarts of water, that works out to a quart a minute. A dehumidifier extracts about 2 quarts an hour( a 2 ton AC can pull 6-8 quarts an hour). If your shop is cooler, say 72 degrees and you just added 3 quarts of water to your shop, your shop will start absorbing heat from the air/water and anything metal will get condensation. 72 degree air(in your 3200 cubic foot shop) can only hold about 2 quarts of water(100 percent relative humidity).

Alan could be right if you setup an inlet at each machine but this seems impractical at best and you would still exchange a fair amount of air.

I run a dehumidifier when I leave my barn but not while I am in it. When kept closed, it stays about 50 percent humidity with the dehumidifier, but will rise to close to outside humidity in only a few minutes if I open a window and put a fan in it.

Heat loss(in winter) would not be as big an issue, as air's heat content, is largely dependant on moisture content, which is very low in cold temperatures even if the relative himidity is high. It has been about 20 years since my Thermodynamics classes but am pretty sure these numbers are about right. If you live in a very low humidity enviroment it may not be too much of an issue, but then I doubt you would ever need a dehumidifier anyway.

[Eduard Nemirovsky]

Thank you very much for explanations!!! I do have Mr. Slim AC with dehumidification. I will try to schedule my work as to decrease time of DC running.
Thank you again.
Ed.

[Myk Rian]

You are going to kill yourself. It will be like opening the door on the space shuttle.
Did you really think you might suffocate?

Put a 1 micron filter on the DC and keep the exhaust in the shop. That way your eyes won't pop out of your head from the vacuum.

[Eduard Nemirovsky]

You are going to kill yourself. It will be like opening the door on the space shuttle.
Did you really think you might suffocate?

Put a 1 micron filter on the DC and keep the exhaust in the shop. That way your eyes won't pop out of your head from the vacuum.
Ha-ha, I know I will not kill myself or suffocate even if I want after big scrue up. I actualy went from filter to venting outside because of noise with filter.

Ed.

[Carl Hunsinger]

It's actually possible he could suffocate himself, if he has a gas water heater in the shop. I'm just sayin'...

Carl

[Howard Acheson]

>>>> will I "suffocate" my dust collection,

I think Eduard is talking about his DC "suffocating", not himself. In other words by not having make up air readily flowing, can he expect reduced DC efficiency?

The answer is yes if he gets resistance when trying to open a door.

[Myk Rian]

People have no sense of humor around here.

[Greg Portland]

... or reading comprehension skills.

[Dan Hintz]

I can't understand what either of you wrote, but I don't find it funny...

[Myk Rian]

Eduard laughed. That's all that matters.

[Dan Hintz]

Awwww, come on, Myk... did I need to put a smiley at the end of it? ;)