Vodkaman

Workshop ventilation

11 posts in this topic

I have just moved to a new abode. The layout is a shop, ground floor will be my work shop, 2nd floor is my living space. Small but very economical. The shop volume is 2942cuft. (21ftx15ft).

My problem is a steady airflow from the shop to the living quarters, especially if a window is open (pretty much a necessity here).

My question is what size fan do I need to solve this problem?

A few web searches seemed to suggest a fan of at least the same volume, i.e. 3000cfm. This to me seemed excessive and is going to be expensive, but the cost will be a secondary consideration.

My plan is to make either a false door, on castors, or replace the existing door, with the fan fitted. I am not allowed to fit the fan to the original door (glass) as the property is rented, nor do I want to tackle the external wall, considering the blatant lack of building codes here, the house would probably collapse!

This is purely for ventilation of wood dust. I will address the problem of paint at a later date, probably with switch able ducting to utilize the same fan.

Experience, advice and suggestions please.

Dave

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Dave,

I think 3000cfm is way higher than you need, that's the entire volume of your shop in one minute. Are you trying to actually remove the dust from the shop or just keep it from going upstairs? If you're just trying to prevent it from dusting up the house, I'd just try to go cheap at first, you might get away with a good sized fan mounted in a piece of plywood mounted in the doorway. All you really need to do is get SOME airflow through it, if you're creating a little bit of negative pressure in the shop, you'll be pulling air from upstairs so the dust can't go that way. You shouldn't need a lot of airflow, just enough to keep the sawdust from going up the stairs.

I know New Jersey is a far cry from Indonesia climate wise, but my spraybooth only moves about 600cfm...........MAYBE 750 and if there's windows open upstairs you can feel the air moving down the basement stairway.

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Clamboni, exactly, just enough to create that negative pressure. This is good news, as I am on a tight budget, also the electrical standard supply is actually only 900w. I have already had to upgrade to 2.2Kw at great expense ($80) and I still have to turn everything off to use the table saw! They want $200 to upgrade to 3.5Kw, it is rediculous.

Thanks for the link Frank. But too expensive, also I would be changing filters every few days. Blowing the dust outside is not a problem, as I am surrounded by other wood and metal contractors with open plan shops. This is a very dusty neighbourhood, have to sweep the front steps daily.

I will be visiting the ventilation shop in the next few days and will aim for around 750 - 1000cfm. Any further comments appreciated.

Dave

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Dave - there is a lot of portable evaporative coolers down at the tip and these are my go to sucker /blower/ sander motors, four speed and cost about $10 here - we call them Pelton Fans (I think) but the 'Yankees' seem to call them 'squirrel cage fans'.

I know evaporative cooling would be as rare as hens teeth there but maybe they use them in some sort of air conditioning or smoke exhaust from a chip shop - they move heaps of air for very little revs/noise - the smaller ones I usually use are about 2' in diameter and are also a great paint extractor with the 4 speeds, on four they will suck your toupee right off your head.

Anyway you know all about this stuff, just suggesting some sources.pete

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Hi Dave,

I can tell you, managing wood dust in a shop is an ongoing task, even with dedicated dust collection systems, finer particles are always an issue.

From your notes, I would not look to create negative pressure, as you will be bringing in the neighbors dust to replace your own. What you want to do is scrub your own air using a filter system.

Id recommend something like what frank posted. I know they are expensive but the unit is fairly easy to build yourself. There is a triangular delta system available here in the states that would suit your square footage. :| you could make it shallower in height and mount it to your ceiling.

I made mine from flakeboard, a squirrel cage motor sourced second-hand (used) from an old hvac unit, and 2) 24"x24" furnace filters. You dont need to replace the filters, simply remove them once a week and clean them outside with pressurized air from your air line.

This is pretty standard in american commercial shops (along with cyclonic wood chip collection)

You might not even need a high powered fan, as long as the negative pressure holds the filters to the unit via suction, if it does, the unit is working. I used a big fan because I had alot more footage (3,000+)

Try your best to control dust at its source (eg; tooling, machines, sanders, etc) and it will help.

When you get into painting, thats a whole new dilema, wood dust and clearcoat dont play well together, I'd recommend looking at a different (and comfortable) space to paint.

Or do your painting there and clearcoat somewhere else, remember, painting (or sanding between coats, sealers, primers) creates dust also.

Good luck :yay:

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Further to Jerry's post here is how to make one (cyclonic extractor) if you have the time. This is a very good site for anything involving wood and finishing.

How to make my Dual Cyclone - Dust Extractor - Woodwork Forums

There are several different guys offering plans if you google it - there is a guy in the States somewhere with a name like Smith or Brown who is quite famous for his extractors, both commercial and he also shows how to build one.

I bought a small one which I attached to my sander, it works quite well in conjunction with a filter.pete

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Jerry, thanks for your input. The thought did occur to me too, that if I pumped the dust out of the house, I would be chewing on a good proportion of it, as it got sucked back through the window upstairs. The problem would likely be worse than it is now. So yes, a filter system will be required.

Pete, thanks for the link, great site. However, I need this thing up and running fast. That set of plans is in dire need of 100 pics. Same with finding a used fan, I would not know where to start looking. It could take weeks, the problem compounded by language difficulties. In the UK, I would go straight to the nearest scrap yard and probably find the perfect solution in no time.

Hopefully, the extractor fan shop that I have found, sells filter material. I will try a circulating system first (no venting outside), with a simple removeable frame mounted filter for ease of cleaning. If this does not solve the problem, I still have all the other options.

This plan is not set in stone and will depend on what I can find in the shops today.

Dave

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After several complants from neighbors, a buddy of mine built a small filter system for his backyard paint shop that used a squirrel cage fan exhausting the air out of the shop thru a couple of hvac filters mounted on the inside wall....the air traveled thru a length of not quite horizontally mouted metal ductwork on the outside of his shop before it Tee'd into a vertically mounted piece of ductwork.....the bottom end of that duct sat in a 30gal barrel of water....the top end stuck up above the roof of his shop.....inside the horizontally mounted ductwork he mounted a series of water misting heads.....When he fired up the system the water sprayers inside the ductwork acted as water scrubbers and filtered out the bulk of the paint from the exhausted air....all the paint collected in the bucket of water and he'd change that out periodicly.....You could stand anywhere near his shop and NOT smell any paint fumes coming from it after that.....He used both Createx and automotive urethanes and clearcoats.....The system was kinda crude, but it worked amazingly well for what it was....although it did kinda make his shop look like a moonshine still.:eek:

Something like this might work for your paint fumes, and maybe even the wood dust....I dunno....Hope i didn't confuse ya with our hillbilly engineering.:whistle: If nessasary I could draw out what I tried to discribe?

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KF, very inventive! Good explanation, I followed the idea, no problem.

Unfortunately, the smaller shops are still closed here, still celebrating the end of Ramadan. Will try again monday.

Dave

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I made and hung the door today and fitted the fan. The shop owner told me that it was 750cfm. It seemed windy enough but I had my doubts, but it was the largest that they had.

A smoke test from 6ft away was not promising, but it has created the negative pressure, which was the object of the exercise, as can be seen from the hanging curtain leading to the stairs.

The motor is only 115w, which is small enough to be left running 24/7, without damaging the wallet.

The door is dry screwed, so that if I find a better fan, I can modify the door to suit.

I have not found any filter cloth for the project as yet, but it hardly seems worth the effort, as the volume of air moved is too small. I did buy some fine material, but it restricts the airflow too much.

I should know in a few days whether my upstairs dust problem has been solved, as I have a couple of shelf units to build, which is going to create about 20ltrs of sawdust.

Thanks for everyones input, I suspect this will be an ongoing project.

Dave

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