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Common Gas Flow Resistivity numbers. Studio Monitors
Old 30th May 2017
  #121
It would be great if all the useful data that people can contributed in this thread was tabulated in the first post.
Old 22nd June 2017
  #122
Gear Head
 

Earthwool product Flow resistivity numbers if anyone is interested.
Sourced direct from Knauf Insulation (Aust)
I think the third column is Flow resistivity in MKS RAYL/M
Attached Thumbnails
Common Gas Flow Resistivity numbers.-image001.jpg  
Old 29th June 2017
  #123
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Thread Starter
Interesting

Thank you flicka, this thread has over 32K views, I guess one could be fairly sure someone is interested.
@daxliniere, that would indeed be great. It would require quite a bit of work filling in numbers into say an Excel. Perhaps with some useful averaging and so on. If anyone wants to go ahead and do this I am certainly willing to do my part by editing it into the Original Thread Starting Post. Thread starting posts become unavailable for Edit after a time. This is to prevent nonsensical 'retrofits'. Moderation have kindly unlocked them for me in past, e.g. in order to update the Room Measuring Primer.
DD

Last edited by DanDan; 30th June 2017 at 03:14 PM..
Old 10th July 2017
  #124
Gear Head
 

I'm working on a project and I have a GFR related question some of you may be able to answer.
I have a 12 ft long tube.
What is the lowest frequency I can take at least 60 dB down at the other end and with which material? Without having the soundwave reflect back before reaching the end.

Thank you for any input!
Old 10th July 2017
  #125
Here for the gear
 

GFR Owens Corning Canada

I just received those numbers from Owens Corning Canada.

Also the information given in the document states that compression can heavily affect the Air Flow Resistivity number.

These numbers are quite impressive! 3600 rayls!! 2ft of that around my room will do nothing but a miracle.
Attached Files
Old 14th July 2017
  #126
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Treasure

That is invaluable, thanks Naisw.
DD
Old 14th July 2017
  #127
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Pleasure to be some kind of help. This community helped me so much in the past couple of months!
Old 19th July 2017
  #128
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Krafty

The Kraft paper or foil is generally intended as a vapour blocker in normal building practice. It is just coincidence that it is useful to us acoustically. It does slightly increase LF absorption of 100mm 100KG semi rigid fibreglass panels. At the same time it does reflect some HF.
http://ethanwiner.com/density.html

DD
Old 2nd March 2018
  #129
Gear Head
Knauf Earthwool Ecose slabs for UK GFR

Knauf Earthwool Ecose slabs for UK

Got this message from them.

"The facings available are white tissue, black tissue and foil, all available to one side only. This would be subject to enquiry and on a non-standard basis. Please contact customer service for further information – 0844 800 0135 or [email protected]."

I posted here because I think this is a definitive list of their stuff available to UK
Attached Files
File Type: pdf Airflow Resistivity Rock.pdf (6.7 KB, 44 views)
Old 2nd March 2018
  #130
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Revealing

That is a very interesting data graph. I note the Resistivity changes dramatically with angle of incidence. Thanks for finding and posting that Carl.
DD
Old 2nd March 2018
  #131
Gear Head
Fibers must be lined up

Quote:
Originally Posted by DanDan View Post
That is a very interesting data graph. I note the Resistivity changes dramatically with angle of incidence. Thanks for finding and posting that Carl.
DD
Looking at the stuff right here in front of me all I can think is that it must be the way the slabs have a layering to the internal structure that causes the difference. Even so I cant believe that the difference is about half. Maybe the actual fibres are all lined up and the wave can just slide through when parallel to their ends?

This is the stuff sold by GIK @ 45 and 60 density
Knauf Insulation Earthwool with ECOSE(R) Technology 45kg/m3 - GIK Acoustics Europe
Except they are always sold out, even though it is readily available elsewhere.
Old 2nd March 2018
  #132
Gear Head
angles of incidence.

What do I need to take into consideration regards the differences at angles of incidence as regards the Knauf GFR in this GFR graph for Knauf Earthwool slabs?

Straddle corners? Are the modes that build up in corners arriving mainly perpendicular to the corner? What would be the optimum angle positioning of this material be in a corner?

Ceiling clouds?
Early reflection points?

I have a half hatched idea that the 10dB 160Hz lump in my room is caused by my 2.2 meter high ceiling? I need treatment up there anyway.

Should I try and get some of the paper backed 45Kg 100mm and leave 100mm air gap with the paper facing the ceiling? I could cover about 1/3rd of the total room, above the speakers mixer and listening position.

Am I going in the right direction? If this stuff is good enough for GIK (they sell it on their UK site)?

Do other manufacturers even publish both perpendicular and parallel GFR results?
Am I worrying too much?
Attached Files
File Type: pdf Airflow Resistivity Rock.pdf (6.7 KB, 21 views)
Old 5th March 2018
  #133
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Regarding fiber orientation vs airflow resistivity; the back pressure felt by the sound wave is a complex impedance with a real (resistive) and an imaginary (reactive) part. The perpendicular fiber presents a bigger area normal to the particle movement than the parallel fiber, causing inertance due to the acceleration/deceleration forces when the air slips around the fiber. This inertive reactance is the imaginary part of the impedance (in electronics we call it inductance). If the fiber is vented into an enclosed volume there is also compliant reactance (acoustic capacitance) contributing to the imaginary part of the impedance.
The real (resistive) part of the impedance is the actual frictional work being done as the air particles rubs along the surface of the fiber. Power is dissipated only by the resistive component of the total impedance, so the effective absorption is not proportional to the resistivity figures above.
Old 5th March 2018
  #134
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...in other words; for a given airflow resistivity, the parallel fibers of higher density would offer more absorption than the perpendicular fibers of lower density, due to the lower inertance and higher real resistance
Old 5th March 2018
  #135
Here for the gear
 

Quote:
Originally Posted by Henke View Post
Regarding fiber orientation vs airflow resistivity; the back pressure felt by the sound wave is a complex impedance with a real (resistive) and an imaginary (reactive) part. The perpendicular fiber presents a bigger area normal to the particle movement than the parallel fiber, causing inertance due to the acceleration/deceleration forces when the air slips around the fiber. This inertive reactance is the imaginary part of the impedance (in electronics we call it inductance). If the fiber is vented into an enclosed volume there is also compliant reactance (acoustic capacitance) contributing to the imaginary part of the impedance.
The real (resistive) part of the impedance is the actual frictional work being done as the air particles rubs along the surface of the fiber. Power is dissipated only by the resistive component of the total impedance, so the effective absorption is not proportional to the resistivity figures above.
That's a very fancy explanation. However here the "perpendicular" and "parallel" is in reference to the face of the panel, not the specific fiber orientation.

The "perpendicular" spec is what you would use if the slab's wide face is exposed to the room as is done for a panel absorber. The "parallel" one is what you would use when considering construction that places the sheet with it's narrow edge facing the room as is done in super chunk type bass traps.
Old 2nd April 2018
  #136
Gear Head
For the Dutch/Belgium market

I asked Isover Netherlands for some specs for comparison with Rockwool 221:

Sonepanel - 8000 Rayls
Multimax 30 - 32000 Rayls
Old 4th April 2018
  #137
Gear Addict
 

Rockwool Prorox: industrial mineral wool

Today I stumbled across a product catalog for industrial mineral wool made by Rockwool, that lists approximations for GFR. I've included the numbers for the products that have been easiest for me to source, and maybe for others to source as well, but I guess it will be city dependent. All the industrial lines are quite a bit cheaper than the residential stuff. For example, the ProRox SL 940 (4.4lb/ft³ actual density) is $.65/ft², 96ft² in a bundle. So in a standard 2ftx4ftx4in panel, there is about $10.40 of mineral wool. Not too shabby.

If you're near NE Oklahoma and can't find it locally, I bought it from LA King Corp in Tulsa. They only stock the SL 940 and SL 960, but can order any of it if you want an entire pallet. As you'll see in the numbers, the SL 920 would be best for 4" acoustic panels (according to most absorber calculators), but unfortunately they don't stock it, and I'll need to buy a full pallet of it: 1124ft² at $.46/ft². That's not too bad for material cost at $593, and I'll need near that, but the freight shipping is $375...

I've also attached the .PDF catalog. There are a lot of different products in there, so take a look if you want numbers on a different product.

Exact GFR numbers would have been helpful, but these are a decent starting place:

ProRox SL 920
Nominal Density: 2.5lb/ft³ (40kg/m³)
Air Flow Resistivity: >10 kPa.s/m²

ProRox SL 930
Nominal Density: 3.4lb/ft³ (55kg/m³)
Air Flow Resistivity: >20 kPa.s/m²

ProRox SL 940
Nominal Density: 4.4lb/ft³ (70kg/m³)
Air Flow Resistivity: >30 kPa.s/m²

ProRox SL 950
Nominal Density: 5lb/ft³ (80kg/m³)
Air Flow Resistivity: >40 kPa.s/m²

ProRox SL 960
Nominal Density: 6.2lb/ft³ (100kg/m³)
Air Flow Resistivity: >60 kPa.s/m²

ProRox SL 970
Nominal Density: 7.2lb/ft³ (115kg/m³)
Air Flow Resistivity: >70 kPa.s/m²

ProRox SL 980
Nominal Density: 9.1lb/ft³ (145kg/m³)
Air Flow Resistivity: >110 kPa.s/m²
Attached Files
Old 2 weeks ago
  #138
Quote:
Originally Posted by avare View Post
I just received an email from Roxul Canada regarding gas flow resistivity values for their products. The reason given that they have so few products tested is that they receive very little requests for that data.



Yes, the Rockboard 40 is 4 lb/ft³ (64 kg/m³) product. That is the nominal non-silicon wool density material that we take as being equivalent to OC 703. So much for across the baord generalizations. It should be noted that in the same manner, Ultratouch insulation (cotton*) appears to have significantly higher gas flow resistivity.

Andre

*I originally wrote sheep's wool. DanDan's following post is correct in what he wrote about sheep's wool.
Okay I need to clear something up that I am very unsure about because of conflicting data.

My local lowes/home depot/ and insulation supply store doesn't carry the Roxul Safe n Sound 24x48 sheets but the insulation supply store does carry the Roxul AFB. According to bob golds and roxul, the safe n sound and afb @3 inches thick is 2.5 PCF. I know the safe n sound has a GFR of like 14910 but I read a post on this thread stating the AFB was actually 2.8 PCF and around 16660 GFR.

So is the data Roxul is providing for the AFB wrong?
Old 2 weeks ago
  #139
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Quote:
Originally Posted by doom3crazy View Post
So is the data Roxul is providing for the AFB wrong?
Thanks for the great research. The difference is not practically significant.

Wht is frustrating is the change in 703. It used to have .85 absorption @125Hz and now it is listed as .63!

Enjoy the AFB!


Andre
Old 2 weeks ago
  #140
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DanDan's Avatar
 

Thread Starter
Unstable

I seem to remember vastly different GFR figures published for 703 before.
Clearly it is cursed.

DD
Old 1 week ago
  #141
So I just wanted to post this here and give as much info as I can. It would seem as though my local home depot(and some others from what I have read) is phasing out the Safe n Sound roxul stuff in favor for the Owens Corning Thermafiber Fire and sound guard( I was able to get the 15 x 47 roxul stuff on clearance for 14$ a bag!)

Here's the new stuff that will replace it. Seems to be pretty much the same.
https://www.homedepot.com/p/Owens-Co...-221/303347027

According to the data sheet it looks pretty much the same in terms of coefficients
https://www.thermafiber.com/wp-conte...Data-Sheet.pdf

And according to this other data sheet has 40 kg/m3(2.5 lbs/ft3)
https://www.thermafiber.ca/wp-conten...a-Sheet-EN.pdf

The only information I was unable to find was the GFR numbers. Maybe one of you guys can help me out in finding that info
Old 6 days ago
  #142
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Thread Starter
No

Not at all. To be honest I recommend that you delete your posts. The purpose of this thread is to store/list actual published GFR data.
DD
Old 5 days ago
  #143
Owens corning emailed me back and said " air flow resistivity for Thermafiber Fire and Sound Guard is about 20,000 mks Rayls/m on average"
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