I've got a line on this stuff:
http://www.knaufusa.com/products/buildi ... ecose.aspx
The guy selling it claims that people have used it successfully as duct liner.
My plan is to use it inside of my silencer.
Thoughts?
Thanks.
EDIT: Link's dead. I had to google search my own post to figure out what the roll of 'acoustical barrier stuff' i have in my attic. Here's the stuff in question:
http://products.construction.com/Manufa ... NST44011-P
duct liner "substitute"?
Originally posted at johnlsayers.com, topic 15765.
check with the manufacturer to see if its suitable for that purpose.
Sounds like it's a go:
And, no, I won't give out my source until I've procured my desired amount. :DIt would be ok to use the Knauf Wall and Ceiling Liner M as a duct liner for silencer boxes. It is the same product as our Sonic XP Duct Liner except it does not have edge coating. The velocity rating for both products is 6000 feet per min.
Caveat emptor !... except it does not have edge coating ...
What should I be worrying about, brihar?
Being in the air circulation, I'd be concerned about airborn particulates. I understand that the sufaces are bonded with a coating but the edges are not. According to your post they say it's similar to their duct liner product - but that the edges are not coated. Obviously the duct liner has all edges coated - for a reason I suspect.
Just thought you might want to consider that.
Since we're on the subject of silencers...........
Would it be best to use backer rod and sealant between the connections similar to how one would do a wall?
My plan is to use ply on the first layer and cover that with 2 layers of 5/8" drywall. I'm just wondering if I should approach this the exact same way one would approach building walls?
I was thinking I'd just build the actual box with "normal" corners (butt joints, glued and screwed) and then surround that box with drywall with the tops, bottoms, and sides being progressively larger than the previous layer (kinda like Russian nesting dolls). For example, a ply box within a larger drywall box within the largest drywall box).
But should the edges of the drywall boxes actually touch or would it be most efficient to use backer rod and sealant where they'd "normally" butt up against each other.
These will be sitting on my attic floor which is the top of my first leaf.
That first leaf is composed of:
(starting from bottom to top)
-1 layer of 3/8" ply
-2 layers of 1/2" drywall
-1 layer of 3/8" ply
(AND YES, STUART, I'M AWARE THAT USING 1/2" DRYWALL ISN'T IDEAL :D )
I've attached the first draft of a skp file for refrence. Note: It does not have the backer rod and/or sealant in the picture (some of the measurements are a bit wacky, I know).
Thanks.
Since the silencer is really more part of either the exterior or interior isolation structure (depending on how your space is arranged) the backer rod etc isn't needed but you do want to caulk and seal, and you want to decouple the passthrough on the isolation boundary to avoid structure transfer as well as avoid any coupling to your ducts etc. On the insulation, if in doubt, cover with plastic or get the duct liner version.
Brian, I have not allowed the used of raw ductboard (or liner) on any of my projects since 1992..... It is polymer lined or it just never sees the light of day.... and for the very reasons you mention - I do not want to introduce fiberglass particles into the air-stream...... not because there is any certain health risk - just simply because it is not a good practice. But you can "over think" these things sometimes - and this is (IMHO) one of those times..... They do not make a little polymer touch up kit for these boards - and (so) every time you take a piece and fit it - you leave a raw, uncoated, edge....... So unless someone is building a box that is dimensioned for full sheets - there are going to be cut edges - no edge coating. This is just a physical reality - and nothing to get excited about...... The idea here is to minimize the probability that there will be a release of particles.... this is accomplished (with cut edges) by making sure that the edges are tight fitting when the construction is completed...... There is no reason to avoid using this product........ Rod Gervais GIK Acoustics Director of Education http://www.gikacoustics.com (USA) http://www.gikacoustics.co.uk (Europe) Tel.(US)[removed] Tel.(UK)+44(0)20.7558.8976Being in the air circulation, I'd be concerned about airborn particulates. I understand that the sufaces are bonded with a coating but the edges are not. According to your post they say it's similar to their duct liner product - but that the edges are not coated. Obviously the duct liner has all edges coated - for a reason I suspect. Just thought you might want to consider that.
Thanks for that info Rod. I'm going to be coming to constructing a silencer in the near future, and have been giving this some thought already. Fitting the cut liner so that the 'raw' edges are not exposed to the air flow makes obvious, simple sense.
Someone also told me that newer products are available made of cotton and denim -
:idea: so maybe I can get an aunt to knit me some. :lol:
Brian, Just go to a goodwill store - you can gt all the bluejeans you want cheap there......... lol Seriously - my pleasure. Rod Gervais GIK Acoustics Director of Education http://www.gikacoustics.com (USA) http://www.gikacoustics.co.uk (Europe) Tel.(US)[removed] Tel.(UK)+44(0)20.7558.8976Thanks for that info Rod. I'm going to be coming to constructing a silencer in the near future, and have been giving this some thought already. Fitting the cut liner so that the 'raw' edges are not exposed to the air flow makes obvious, simple sense. Someone also told me that newer products are available made of cotton and denim - :idea: so maybe I can get an aunt to knit me some. :lol:
What would be the best way to assure that edges are tight fitting? I'm well aware that there's a 'common sense' assumption going on here but, as with many of the other processes involved with this project, common sense isn't always 100%. Any tips are most appreciated. Thanks.The idea here is to minimize the probability that there will be a release of particles.... this is accomplished (with cut edges) by making sure that the edges are tight fitting when the construction is completed......
The first is to cut slightly oversized - you want to make sure there is just a touch of compression on all surfaces when you put the material inside the box,,,,,,, Next would be to make certain that you clear off any loose particles before that install....... And (for those who might still have concerns) you could always install a duct filter directly at the outlet into the room. If the airflow were to drop over time simply remove the supply register and replace the filter. This only after checking/changing the return air filter at the air handler unit. One note of CAUTION: The placement of a filter at the supply register (or multiple registers as the case might be) is NOT a substitute for a the filter at the air handler unit (which should be installed on the return air side of the system)...... failure to use a return air filter will result in your cooling/heating coils becoming clogged and will cost you a LOT of money in system repairs....... The additional filter is strictly meant to capture any possible release of fiber over time (over kill in my opinion - but I do have to mention it). If the return air is properly filtered - and the duct liner properly installed - in theory this filter should never require changing. Rod Gervais GIK Acoustics Director of Education [url="http://www.gikacoustics.com"][COLOR="Blue"]Gik Acoustics USA[/COLOR][/url] [url="http://www.gikacoustics.co.uk"][COLOR="Blue"]Gik Acoustics Europe[/COLOR][/url] Tel.(US)[removed] Tel.(UK)+44(0)20.7558.8976What would be the best way to assure that edges are tight fitting? I'm well aware that there's a 'common sense' assumption going on here but, as with many of the other processes involved with this project, common sense isn't always 100%. Any tips are most appreciated. Thanks.The idea here is to minimize the probability that there will be a release of particles.... this is accomplished (with cut edges) by making sure that the edges are tight fitting when the construction is completed......