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Small Machine Shop Ventilation Ideas/ Solutions

DavidScott

Diamond
Joined
Jul 11, 2012
Location
Washington
I have been asked a few times to post about what I have done to increase the air quality in my shop so here goes. I don't wish to imply that my solutions are best for everyone but it is something I have been working on ever since I started my shop. What I have now is a Fantech Hero 200 heat recovery ventilator with a Mistaway unit whose sole purpose is to filter the air for the HRV, some 6" flex duct, and a 6" Fantech centrifugal inline duct fan to remove the mist from the air before going into my ducts. If you don't remove the mist your ducts will quickly be dripping with coolant. I bench-tested my duct fan by blowing a thick water mist into it with a paint gun and nothing came out of the exhaust end so I see no reason to use anything else to remove the mist. Occasionally I will spray water into it while on to wash the coolant out. I drilled drain holes in the bottom ring so any coolant that it removes will drain back into the machine.

My HRV flows around 218 cfm which is enough for one mill, at the end of the day I have zero coolant mist on my safety glasses. When it is warm out I bypass it and get around 400 cfm. When sanding or working with chemicals I have 2 ducts I can move around to where I need them.

The only downside to the commercial HRV is that it will drastically slow the fresh air fan when the outside temp drops to around 25f so keep this in mind. When you need it most it quits working.

My first HRV was made from 6' lengths of 4" and 8" aluminum duct that I made myself. It recovered around 50% of the heat from the exhaust air and kept working even when it got really cold out. I was planning on making another one using 8" and 12" 10' or 12' long aluminum duct before buying the Fantech but I still might since the Fantech doesn't work when it gets cold, and it would probably be more efficient. If I do make it I will mount a 3"-4" PVC pipe in the middle to support it and force the air closer to the 8" duct. Cold air through the 8" duct and exhaust out the 12". I made internal spacers/turbulators out of aluminum flashing mounted every 2' to space the ducts apart.

Vent-3 shows the centrifugal fan installed on my Brother and Vent-5 shows a plastic bag held in place with magnets covering the coolant trough out of the machine. I did this to stop any air from coming into the machine here, I want it all to come in the operator's station at the other end. It was just a quick fix but works perfectly well.
 

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We really struggle with mist generated from our lathes; Mistaways and (Haas branded :rolleyes5:) mist condensers can't keep up, and I am somewhat skeptical that splurging for a high-zoot unit like a 3nine is going to work any better-but at least they look like rocket engines!

To clarify you have machine->mistaway->centrifugal fan->HRV->outside?

Probably a dumb question but if the centrifugal fan can extract most of the coolant from the air (and drip it back into the machine) why does it need to be ducted outside at all?

We have also been working on dust collection for cast iron machining, and I'm intrigued by the centrifugal separator idea...
 
I have found that by cultivating a porn star mustache and having copious nasal hair I can filter most of the coolant out before it gets into my lungs. :D

Thanks for posting, I need to sort something out as my current solution is not working very well.
 
We really struggle with mist generated from our lathes; Mistaways and (Haas branded :rolleyes5:) mist condensers can't keep up, and I am somewhat skeptical that splurging for a high-zoot unit like a 3nine is going to work any better-but at least they look like rocket engines!

To clarify you have machine->mistaway->centrifugal fan->HRV->outside?

Probably a dumb question but if the centrifugal fan can extract most of the coolant from the air (and drip it back into the machine) why does it need to be ducted outside at all?

We have also been working on dust collection for cast iron machining, and I'm intrigued by the centrifugal separator idea...
I have the centrifugal fan mounted at the machine to remove the mist before it goes into the ductwork, then the Trimist filter with the electronic cells removed and only using the other filters in it with a 1" thick furnace filter before the air leaves it, then the HRV, then outside. When I am not heating my shop I bypass the HRV and double the air flow. To cool my shop I use an evaporative cooler which is open loop so no need for the HRV.

For venting the machines the HRV also gets rid of the stink, as well as all the stuff you can't see. In my case, I also vent things you DO NOT want to breathe and can't filter out so the HRV is necessary for those things.

I use the same system to vent grinding aluminum so I am not breathing the dust but use a filter at the source to reduce what goes into the ducts. If I made more dust I would try one of those cyclone filter setups for a 5-gallon pail before the home furnace filter.

mistaway can't be replaced by something lowcost ?
I got the Trimist with a used machine so it was basically free. All it is in my setup is a box with filters in it and a variable speed fan to pull the air through it rated around 500 cfm max. I watch the duct that connects the Trimist to the HRV to get the airflow balanced through the HRV.
 








 
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