Author Topic: asbestos removal - neg air pressure  (Read 597 times)

affordablehousing

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asbestos removal - neg air pressure
« on: May 13, 2019, 04:52:14 PM »
MMM forum, I'm prepping to do a furnace replacement, taking MMM's advice. Step one for me is to remove 4 asbestos wrapped ducts (just the ducts, no paper on the register boots). I was reading up on how to do it, and get the general idea that you set up the containment room at the entrance (in my case to the crawlspace), mask off all the registers, wet the ducts with a soapy water solution, wrap them first in plastic, then collapse them into sections and double bag them. Fortunately legal disposal is free and convenient in my area. When I was getting quotes for the work, one group stressed having a hepa filtered fan to maintain negative pressure. It looks like they can be rented easily from HD for $159, (filter cost is a lot). In practice, do you need this extra precaution?

Perhaps I'm crazy? If you think so tell me. But with the 40 feet of 6" duct removal costing three times the furnace, it seemed worth it to attempt myself.

Papa bear

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Re: asbestos removal - neg air pressure
« Reply #1 on: May 13, 2019, 10:13:17 PM »
This your only time?  Or are you regularly in demo on old places?   If this is a ďI probably wont mess with this again,Ē Iíd go for it. Get a decent mask that will filter out asbestos. Keep everything wet, and try not to disturb the asbestos tape, as in take it all out in 1 piece, donít cut through it. Bag it up and dispose of it. 

I donít think Iíd worry about the fan though.  If this was insulation, or something that would easily get airborn, I would go that route.  But the ductwork? It probably gets  more ďdisturbedĒ every time you walk near a register and the floor deflects and moves the ducts around anyway.

As with most things, reduce exposure.  If you arenít doing this on the regular youíll probably be fine. 

Note for the naysayer fearmongers:  I say probably be fine. There is always a risk in anything.  You probably have a greater chance on a major injury cutting yourself on some metalwork or falling on the stairs hauling it out, though.


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AMandM

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Re: asbestos removal - neg air pressure
« Reply #2 on: May 14, 2019, 07:14:53 AM »
Since you're working in a crawlspace, the fan seems like a bad idea. It will raise up a lot of dust, including asbestos dust. Wetting everything down and leaving it in the crawlspace seems better, since you presumably won't be going into the space once the furnace is installed.
Non-expert opinion from a random internet stranger, albeit one who removed asbestos tile from her basement without a fan.

coffeefueled

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Re: asbestos removal - neg air pressure
« Reply #3 on: May 14, 2019, 08:17:50 AM »
Major injury from cutting yourself on something and exposure to a proven cause of cancer are pretty different. I suggest doing some intense research on industry standards for asbestos removal and base your decision on that rather than anything suggested by MMM forums. Not saying we aren't well-meaning and smart, but that doesn't make up for lack of specific knowledge about how to handle a dangerous substance.

Sibley

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Re: asbestos removal - neg air pressure
« Reply #4 on: May 15, 2019, 08:22:02 AM »
Bit of common sense: yes, asbestos (and lead) are dangerous. However, the level of hysteria that's out there regarding both is really over the top, and unhelpful.

The people who are really at risk for asbestos related cancer are the ones who have frequent, long term exposure. It's not the DIY-er who got exposed once or twice. But that doesn't mean you want to breath it in. Any sort of dust or particles in your lungs is bad. So, common sense. Not paranoia.

Fishindude

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Re: asbestos removal - neg air pressure
« Reply #5 on: May 16, 2019, 06:41:14 AM »
Bit of common sense: yes, asbestos (and lead) are dangerous. However, the level of hysteria that's out there regarding both is really over the top, and unhelpful.

The people who are really at risk for asbestos related cancer are the ones who have frequent, long term exposure. It's not the DIY-er who got exposed once or twice. But that doesn't mean you want to breath it in. Any sort of dust or particles in your lungs is bad. So, common sense. Not paranoia.

/\ /\  THIS  /\ /\
Wear a respirator, goggles gloves and a long sleeve shirt, carefully remove the material and place directly in plastic bags, then dispose of it.
Remove and wash the PPE and clothing and get a shower right after.

BudgetSlasher

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Re: asbestos removal - neg air pressure
« Reply #6 on: May 17, 2019, 05:41:15 AM »
I have no experience with asbestos, but any time I do something inside that could kick up dust (things like drywall work, or sanding cabinets) I like to do as you've already mentioned and seal off the area. I also like to have negative pressure in the area; basically I take a floor fan (something like this https://www.homedepot.com/p/Commercial-Electric-24-in-Heavy-Duty-2-Speed-Direct-Drive-Tilt-Drum-Fan-BF24TFCE/303061463) out of my workshop and rig it up to a door or window opening to blow air out (and most of the airborne dust).

If working with asbestos I, personally, would consider doing something similar to ensure that any asbestos that is disturbed does not become part of my household dust.

As for the HEPA . . . I can understand why the professionals use it and why it couldn't hurt, but at such a small scale like yours . . . that's a personal call.

Papa bear

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Re: asbestos removal - neg air pressure
« Reply #7 on: May 17, 2019, 09:07:33 AM »
To clarify on some other comments, including mine, and the work that I expect is being done for OP:

This is the removal of asbestos tape on metal ductwork.  There really isnít any risk of dust or particulates with this.  Typically it is still exposed in a basement or open crawl space anyway.   

When you remove that portion, you arenít removing the tape, you are taking the entire section of ductwork out with the tape still on it.   Ductwork is screwed into place with machine screws.  If thatís not accessible, you can cut it with tin snips or a hacksaw.  So you donít mess with the actual asbestos  at all. Then double bag it up and take it outside. Anyone with an old house with old forced air systems and an unfinished basement will probably have the same asbestos exposure just walking under the ducts as when you take this out.   

Mitigating your risk involves encapsulating asbestos fibers, not getting asbestos airborne, and keeping fibers from getting in your lungs. 

Encapsulating: spray adhesive, tape over existing with different tape, cover section with plastic before removal

Airborne: wet down asbestos, donít damage, disturb, or cut through it, take it down in full pieces / sections. Bag it immediately.

Lungs: mask, respirator, take off your clothes and wash them after working, recycle air through working area. Other ppe specialty clothing (tyvek coveralls), filters that are made for asbestos fibers on fans/vacuums.

So for this job, I would, and have previously done, tape the existing asbestos, wet it with a spray bottle, worn a respirator (though not rated for asbestos and I have a beard which makes them much less effective.) and I probably went absolutely overkill.

Iíve gone through some demo projects where we didnít know there was asbestos until after the tear out has started.   It had a greater chance of being airborne. After that, we took more precautions, including negative air pressure with box fans in windows, respirators, lots of water, and being careful to take out large chunks of drywall manufactured in the 20ís.


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Fishindude

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Re: asbestos removal - neg air pressure
« Reply #8 on: May 17, 2019, 11:29:47 AM »
Back in the day we used Transite board (which is asbestos) behind shower tile walls, etc.   Cement board was not yet available.
Was standard practice to cut that stuff with a circular saw and let the dust fly, as well as drilling holes in it for fasteners, etc.   Nobody gave it a second thought.

Most of the folks that had severe respiratory problems from asbestos were the folks that installed blanket type asbestos insulation on pipes and boilers day in and day out, many of which were on ships, in large manufacturing plants, large municipal buildings, etc.

It's really a very overblown hazard.   Don't breath in the dust from it and you'll be fine.
The new hot item to replace asbestos as a hazard (for the ambulance chasing lawyers) is silica dust, which is the dust generated anytime you cut or grind stone, bricks, block, concrete, etc.


Papa bear

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Re: asbestos removal - neg air pressure
« Reply #9 on: May 17, 2019, 12:41:27 PM »
Back in the day we used Transite board (which is asbestos) behind shower tile walls, etc.   Cement board was not yet available.
Was standard practice to cut that stuff with a circular saw and let the dust fly, as well as drilling holes in it for fasteners, etc.   Nobody gave it a second thought.

Most of the folks that had severe respiratory problems from asbestos were the folks that installed blanket type asbestos insulation on pipes and boilers day in and day out, many of which were on ships, in large manufacturing plants, large municipal buildings, etc.

It's really a very overblown hazard.   Don't breath in the dust from it and you'll be fine.
The new hot item to replace asbestos as a hazard (for the ambulance chasing lawyers) is silica dust, which is the dust generated anytime you cut or grind stone, bricks, block, concrete, etc.

Youíre not kidding me on the silica dust side.  Iíve got a neighbor that owns a commercial concrete company and he wasnít very happy with the new changes.  Itís getting a bit ridiculous.   Itís no longer good enough to wet down the concrete and use a mask/respirator when sawcutting. 






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dougstash

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Re: asbestos removal - neg air pressure
« Reply #10 on: May 17, 2019, 08:54:00 PM »
If you are concerned about asbestos fibers entering your living area you want to plastic off a containment area and calculate the cubic feet of the area. Use a negative air scrubber rated for said CFH with a heapa filter and perform the work using a fit tested respirator and a tyvec suit to avoid unwanted contamination of clothing.  Itís not really about pressure.   I personally wouldnít bother going to the extremes though.  Id just wear the tyvec suit and have a good respirator (not a paper mask) and hang plastic where any dust can travel into the house. 

And in response to silica:  that really is some bad shit. Silicosis is a real issue and lots of people have real health problems because of it.  Wetting concrete to cut can be good enough so as long as the limit of 50 micrograms/ cm2 is not exceeded. If that is the only engineering control you can use and levels will exceed that then you need to wear a respirator. I donít see a problem in that. Additionally it really doesnít lake much time to hook a vacuum up to a rotary hammer or jackhammer to limit fine respiratory silica and it makes cleanup go a lot faster.  Iím without a doubt in favor of the new limits. A casual DIY really wonít need to take as many precautions but no full time construction employe should  have to be exposed to high levels of toxic dust without the right protection just to squeeze out more profit.

Fishindude

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Re: asbestos removal - neg air pressure
« Reply #11 on: May 18, 2019, 11:14:52 AM »
Additionally it really doesnít lake much time to hook a vacuum up to a rotary hammer or jackhammer to limit fine respiratory silica and it makes cleanup go a lot faster. 

You've not spent much time around rotary hammers or jackhammers obviously.
I've never seen either of these tools with a vacuum hook up port and have owned and operated a whole bunch of them.   Very impractical idea.