DIY air filtration unit for <$200

[Dan Hintz]

At 1.4A, that thing would probably drop to 0 CFM at even a hint of moisture in the air...

[Robert Walters]

At 1.4A, that thing would probably drop to 0 CFM at even a hint of moisture in the air...

They use those for when people go into sewer manholes.

Were you talking high humidity or something?
I'm not planning on lasering watermelons here =)

[Richard Rumancik]

Robert, I'm not sure what Dan meant but in any event the item you have identified is intended to be used as a fan, not a blower. By that I mean it was not designed to be used against any sort of impedance (restriction). You can't add ducting to a fan and make it into a blower. The reason why they don't specify static pressure is because it will generate the specified flows only at 0" water (no restrictions on intake or exhaust ports). As soon as you add any restriction on either end, the flow will go way down drastically.

Sometimes the terms fan and blower are used interchangeably but the unit you show is clearly meant to move a high volume of air with very minimal backpressure. For laser systems you need a unit that can generate around 6" of static pressure with a flow usually in the neighbourhood of 400-800 cfm - but it depends on the laser manufacturer's specs.

[Robert Walters]

Richard,

There's actually a duct that goes with that:
http://www.harborfreight.com/8-inch-...uct-97763.html

Though they do say that for each 90 bend, the CFM drops.



I'm STILL looking for that happy medium without the amperage and noise pollution, but looks likes I'm going to buy Dan's Red beast tomorrow:

http://www.harborfreight.com/1-hp-mi...tor-94029.html

as I can at least speed control it a bit, where as the green one:

http://www.harborfreight.com/13-gall...tor-31810.html

as I understand it can NOT be speed controlled.

[Richard Rumancik]

Yes, I suppose that if you want to vent a manhole you could attach a piece of large diameter duct to the intake, position it into the manhole, and hope for the best. But the unit is really not suitable for integration into a laser system.

[Dan Hintz]

At 1.4A, that thing would probably drop to 0 CFM at even a hint of moisture in the air...

Let me rephrase that...

At 1.4A, that thing would probably drop to 0 CFM at 0.000000001" of water...

There's a huge difference between high CFM at 0" of water and even low CFM at 4-6" of water. It might give a mighty breeze when set in the open, but hook it to a laser and expect it to pull any pressure and you can expect it to do little more than make some noise.

[Robert Walters]

At 1.4A, that thing would probably drop to 0 CFM at 0.000000001" of water...

Ah, gotcha.


I found the "PERFECT" exhaust system... NOT!
http://www.sears.com/shc/s/p_10153_1...3000P?prdNo=16

But good for a laugh anyway!


Wouldn't you know it...
HF (retail store) is OUT-OF-STOCK of your demon dust collector today!
Maybe that's telling me something, I just can't win it seems.

[Robert Walters]

Dan,

I bit the bullet and got the Harbor Freight red DC.

I was surprised as it's really not as loud as I thought it would be,
for an office it be loud, for a shop fairly quiet (subjective I suppose).


In your air scrubber...

What were your goals in the use of the filters?
Both HVAC and the ShopVac HEPA?

Since you are recirculating air in the room, I suspect that's why the HEPA filter, but the HVAC filter I'm note sure about, unless you have the air scrubber for a dual purpose as I would think a laser isn't going to have much more than the occasional scrap of paper/particle once in a great while and aluminum screen could resolve that. Over engineering???

And if you have some better pics of the HVAC ones and how it's used inline, that would be appreciated.

How much activated charcoal "dust" have you accumulated on the the bottom of the pile? Is it enough that it needs to be filtered to prevent escaping out? Is it actual dust (like baking flour) or like grains of salt/sand?

When/if the "dust" builds up, does it have a significant effect on the throughput?

Sorry for all the questions, I'm working on an idea I have and just trying to figure out if it's "good enough" or if I'm over-engineering the thing and I'd rather learn from other's experiences instead of reinventing the wheel.

[Dan Hintz]

Robert,

The HVAC filters are there mostly to catch the "big" stuff and prevent it from contaminating the charcoal pellets, as well as allowing the air a large surface area to pass through for the charcoal. It also acts as a nice tray to hold the pellets. The pellets are about 4mm in size.

[Robert Walters]

Robert,

The HVAC filters are there mostly to catch the "big" stuff and prevent it from contaminating the charcoal pellets, as well as allowing the air a large surface area to pass through for the charcoal. It also acts as a nice tray to hold the pellets. The pellets are about 4mm in size.

What about carbon dust?

I would suspect that after some prolonged use, there would be a build up of activated carbon dust on at the bottom of the pellets.

I was just wondering if this is minimal (<1/4") or significant (1" or more) between change outs?

[Dan Hintz]

I ran it for a few seconds without the filter, then I ran it for a few minutes with, removed filter, tapped it clean, then ran as normal.

[Shawn Cavaretta]

thanks for posting this info. over the weekend i built a unit it is a wood box 12w 20d 24 h.

i have about 2 1/2 in of carbon in there now and i still have a slight odor when cutting wood and acrylic. im thinking about adding another inch tomorrow and seeing of that works. what do you think

[Mike Null]

Keep in mind that the unit can be working as designed and residual odor may remain in the room from the items you have cut.

[Shawn Cavaretta]

i added an extra 1 1/2 of carbon for a total of 4 inches and i am getting no smell

i will post a drawing of my set up later this week

[Gary Liberman]

Hello, as you know we are about to receive our new ULS 4.60 system, and I would like to know if its mandatory, or better for the system to install an air filtration unit?

Thank you!