Re: The Plot (but not the foam) Thickens
I am presently getting ready to install the "1-inch" polystyrene in a
Birdwatcher-2. Jon, your comments are of much interest!
The stuff is closed cell, so, it has no simple way for the interior
gas to enter or exit. If the sea level pressure was 1000 mb, at 5000
ft the pressure would be about 835 mb. The interior gas is going to
expand (sn't that "Boyle's Law?) until the surrounding forces
equalize. If the foam is in a sandwich with plywood on each side, the
issue would get interesting at the point where the plywood is glued
to a frame. The frame would not expand, and the pressure of the foam
would be trying to break things apart. The amount of this pressure
is limited by the strength of the foam, which I think is 15 pounds
per square inch, minimum. This is probably not enough to hurt the
wood, but rather would cause the plywood to bulge some, in the region
away from the frames. None of this sounds too good, but it may be OK.
The forces trying to push the frames apart would not see too many
square inches to push on and would not likely damage anything. What
could occur is to have the foam edges crushed and when the pressure
is increased, again, there would be a gap all around the foam sheet.
I think I will make up a sample including frames around the sandwich
to see what happens with changing altitude.
Incidentally, I live near sea level, but plan to use the BW-2 in a
variety of places, including nmountain lakes at 5000+ ft. Hmmm...
Thanks for bringing this up.
Bob Larkin
Corvallis, Oregon
--- Inbolger@yahoogroups.com, "adventures_in_astrophotography"
<jon@k...> wrote:
Birdwatcher-2. Jon, your comments are of much interest!
The stuff is closed cell, so, it has no simple way for the interior
gas to enter or exit. If the sea level pressure was 1000 mb, at 5000
ft the pressure would be about 835 mb. The interior gas is going to
expand (sn't that "Boyle's Law?) until the surrounding forces
equalize. If the foam is in a sandwich with plywood on each side, the
issue would get interesting at the point where the plywood is glued
to a frame. The frame would not expand, and the pressure of the foam
would be trying to break things apart. The amount of this pressure
is limited by the strength of the foam, which I think is 15 pounds
per square inch, minimum. This is probably not enough to hurt the
wood, but rather would cause the plywood to bulge some, in the region
away from the frames. None of this sounds too good, but it may be OK.
The forces trying to push the frames apart would not see too many
square inches to push on and would not likely damage anything. What
could occur is to have the foam edges crushed and when the pressure
is increased, again, there would be a gap all around the foam sheet.
I think I will make up a sample including frames around the sandwich
to see what happens with changing altitude.
Incidentally, I live near sea level, but plan to use the BW-2 in a
variety of places, including nmountain lakes at 5000+ ft. Hmmm...
Thanks for bringing this up.
Bob Larkin
Corvallis, Oregon
--- Inbolger@yahoogroups.com, "adventures_in_astrophotography"
<jon@k...> wrote:
>insulation.
> Recall that last week we were talking about blue styrofoam
> I had mentioned that the foam I used on FastBrick turned out to beof 2"
> thicker than the nomial dimensions I planned for - 2-1/8" instead
> and 1-1/16" instead of 1". I hypothesized that the elevation of mymy
> shop might be the problem due to lower atmospheric pressure. Peter
> Lenihan and a couple of other folks offered to measure samples of
> foam closer to sea level.and
>
> Well now, I gathered a couple of samples of my foam this weekend,
> to my surprise they now measure 2-1/16" and 1" exactly. They haveover
> both "lost" 1/16" in thickness over about 8 months time. Now I'm
> really wondering what's going on - outgassing of something left
> from the manufacturing process, perhaps?Perhaps
>
> Anyone else want to speculate?
>
> I'll still mail the samples to Peter for another measurement.
> after some time at sea level they may change again.
>
> Jon Kolb
>
Could the barometric air pressure change at a given elevation also affect
it ? Could a tornado or hurricane eye cause a boat to explode? Yes,
this is not a serious comment.
I am interested and surprised in this thread because it has some
consequences in the use of unicellular Styrofoam! Does the dimension
change? Have you measured the other two dimensions? Those two dimensions
should change much more dramatically.
On Wed, 12 Oct 2005 14:23:26 -0000 "adventures_in_astrophotography"
<jon@...> writes:
Recall that last week we were talking about blue styrofoam insulation.
I had mentioned that the foam I used on FastBrick turned out to be
thicker than the nomial dimensions I planned for - 2-1/8" instead of 2"
and 1-1/16" instead of 1". I hypothesized that the elevation of my
shop might be the problem due to lower atmospheric pressure. Peter
Lenihan and a couple of other folks offered to measure samples of my
foam closer to sea level.
Well now, I gathered a couple of samples of my foam this weekend, and
to my surprise they now measure 2-1/16" and 1" exactly. They have
both "lost" 1/16" in thickness over about 8 months time. Now I'm
really wondering what's going on - outgassing of something left over
from the manufacturing process, perhaps?
Anyone else want to speculate?
I'll still mail the samples to Peter for another measurement. Perhaps
after some time at sea level they may change again.
Jon Kolb
Bolger rules!!!
- no cursing, flaming, trolling, spamming, respamming, or flogging dead
horses
- stay on topic, stay on thread, punctuate, no 'Ed, thanks, Fred' posts
- Pls add your comments at the TOP, SIGN your posts, and snip away
- Plans: Mr. Philip C. Bolger, P.O. Box 1209, Gloucester, MA, 01930, Fax:
(978) 282-1349
- Unsubscribe:bolger-unsubscribe@yahoogroups.com
- Open discussion:bolger_coffee_lounge-subscribe@yahoogroups.com
YAHOO! GROUPS LINKS
Visit your group "bolger" on the web.
To unsubscribe from this group, send an email to:
bolger-unsubscribe@yahoogroups.com
Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
[Non-text portions of this message have been removed]
it ? Could a tornado or hurricane eye cause a boat to explode? Yes,
this is not a serious comment.
I am interested and surprised in this thread because it has some
consequences in the use of unicellular Styrofoam! Does the dimension
change? Have you measured the other two dimensions? Those two dimensions
should change much more dramatically.
On Wed, 12 Oct 2005 14:23:26 -0000 "adventures_in_astrophotography"
<jon@...> writes:
Recall that last week we were talking about blue styrofoam insulation.
I had mentioned that the foam I used on FastBrick turned out to be
thicker than the nomial dimensions I planned for - 2-1/8" instead of 2"
and 1-1/16" instead of 1". I hypothesized that the elevation of my
shop might be the problem due to lower atmospheric pressure. Peter
Lenihan and a couple of other folks offered to measure samples of my
foam closer to sea level.
Well now, I gathered a couple of samples of my foam this weekend, and
to my surprise they now measure 2-1/16" and 1" exactly. They have
both "lost" 1/16" in thickness over about 8 months time. Now I'm
really wondering what's going on - outgassing of something left over
from the manufacturing process, perhaps?
Anyone else want to speculate?
I'll still mail the samples to Peter for another measurement. Perhaps
after some time at sea level they may change again.
Jon Kolb
Bolger rules!!!
- no cursing, flaming, trolling, spamming, respamming, or flogging dead
horses
- stay on topic, stay on thread, punctuate, no 'Ed, thanks, Fred' posts
- Pls add your comments at the TOP, SIGN your posts, and snip away
- Plans: Mr. Philip C. Bolger, P.O. Box 1209, Gloucester, MA, 01930, Fax:
(978) 282-1349
- Unsubscribe:bolger-unsubscribe@yahoogroups.com
- Open discussion:bolger_coffee_lounge-subscribe@yahoogroups.com
YAHOO! GROUPS LINKS
Visit your group "bolger" on the web.
To unsubscribe from this group, send an email to:
bolger-unsubscribe@yahoogroups.com
Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
[Non-text portions of this message have been removed]
Recall that last week we were talking about blue styrofoam insulation.
I had mentioned that the foam I used on FastBrick turned out to be
thicker than the nomial dimensions I planned for - 2-1/8" instead of 2"
and 1-1/16" instead of 1". I hypothesized that the elevation of my
shop might be the problem due to lower atmospheric pressure. Peter
Lenihan and a couple of other folks offered to measure samples of my
foam closer to sea level.
Well now, I gathered a couple of samples of my foam this weekend, and
to my surprise they now measure 2-1/16" and 1" exactly. They have
both "lost" 1/16" in thickness over about 8 months time. Now I'm
really wondering what's going on - outgassing of something left over
from the manufacturing process, perhaps?
Anyone else want to speculate?
I'll still mail the samples to Peter for another measurement. Perhaps
after some time at sea level they may change again.
Jon Kolb
I had mentioned that the foam I used on FastBrick turned out to be
thicker than the nomial dimensions I planned for - 2-1/8" instead of 2"
and 1-1/16" instead of 1". I hypothesized that the elevation of my
shop might be the problem due to lower atmospheric pressure. Peter
Lenihan and a couple of other folks offered to measure samples of my
foam closer to sea level.
Well now, I gathered a couple of samples of my foam this weekend, and
to my surprise they now measure 2-1/16" and 1" exactly. They have
both "lost" 1/16" in thickness over about 8 months time. Now I'm
really wondering what's going on - outgassing of something left over
from the manufacturing process, perhaps?
Anyone else want to speculate?
I'll still mail the samples to Peter for another measurement. Perhaps
after some time at sea level they may change again.
Jon Kolb