laminated glass tubes
in [Physics]
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From: Uncle Al on 19 Dec 2009 18:34 Lauri Levanto wrote: > > Uncle Al wrote: > > > > The cute part is seeing critical point opalescence for CO2, N2O, SF6, > > CF3Br, propane, CCl2F2, CH2F2, ethylene, C2F6, etc. Gotta have a > > through-sight path. > > > > What aren the hazards? > Glass shards of explosion, > Expanding gas volume? > some materials are volatile? > > You apparently want to warm up and cool in mionutes. > That is lot of stress on any glass. > > Shards can be conteiined between laminated windows > Escapinh gas needs a safe path out > Fire hazard must be in control. > > For heating and cooling it is better to have the protective > windows at some distance so they do not increase the thermal mass. > > observer || U || light source > where || are flat laminated windows, U is the test vial. > -lauri The hazard is not the thick wall glass tube. The hazard is surface damage allowing the glass to fail in tension. A wafer of boron carbide can have a razor edge. Stroke it across a glass tube normal to the long axis. the imperceptable scratch, when flexed scratch outward, parts the tube as though it were never one piece. Coat the glass with polymer so the glass is not at the surface. Mistreatment will still burst the tube. A inch of weatherized polycarbonate will contain any shrapnel, but its large refractice index plus low Abbe number distorts and colors the image. The modern solution is to have a competent tube behind a barrier, a 45-degree mirror, and usually a videocam. -- Uncle Al http://www.mazepath.com/uncleal/ (Toxic URL! Unsafe for children and most mammals) http://www.mazepath.com/uncleal/qz4.htm
From: Mark Thorson on 21 Dec 2009 20:12 Uncle Al wrote: > > Mark Thorson wrote: > > > > What about a box that is metal on all sides > > but one, the latter being the laminated plate > > glass? > > > > Or maybe metal on all sides with a video > > camera and lamp inside with the tube. > > The cute part is seeing critical point opalescence for CO2, N2O, SF6, > CF3Br, propane, CCl2F2, CH2F2, ethylene, C2F6, etc. Gotta have a > through-sight path. Why do people use CO2? Wouldn't one of those other molecules be a lot safer? What would be the safest candidate?
From: Bernhard Kuemel on 23 Dec 2009 06:28 Mark Thorson wrote: > Uncle Al wrote: >> Mark Thorson wrote: >>> What about a box that is metal on all sides >>> but one, the latter being the laminated plate >>> glass? >>> >>> Or maybe metal on all sides with a video >>> camera and lamp inside with the tube. >> The cute part is seeing critical point opalescence for CO2, N2O, SF6, >> CF3Br, propane, CCl2F2, CH2F2, ethylene, C2F6, etc. Gotta have a >> through-sight path. > > Why do people use CO2? Wouldn't one of those > other molecules be a lot safer? What would be > the safest candidate? CO2 is cheap and available. It has an excellent critical temperature. You can make it critical with body heat or other low power heating and cool it below critical with ambient temperature. It is non toxic, non ozone depleting (influences availability). Its (super)critical pressure is low enough so it can be contained in glass tubes. CClF3 has great critical data (29�C, 39 bar), but it is ozone depleting and hard to get. C2F6 has even lower pc (33 bar), but Tc is silghtly too low (19 �C) so it would have to be cooled to go subcritical. It's expensive (compared to CO2) and I would have to buy or rent a pressure bottle. And even at 33 bar (or more if supercritical) a protective case is very preferable. So I just use CO2. Supercritical CO2 is also used industrially and so is particularly interesting for people to watch. Ohh, BTW, Helium would be the safest candidate: 2.3 bar, but at 5 K. :) Or something like C7F16 with 16 bar and 202 �C in an oil bath might be an option. Bernhard
From: Charles on 19 Jan 2010 14:12 On 18/12/2009 17:08, Bernhard Kuemel wrote: > jonnie wrote: >> "Bernhard Kuemel"<bernhard(a)bksys.at> wrote in message >> news:47006$4b2b8cfc$557f66e5$13738(a)news.inode.at... >>> Hi! >>> >>> I make display glass tubes with high pressure content (up to 200 bar). >>> To protect the tubes from damage and to protect the spectators from >>> shrapnel in case of an explosion I try to make a protective cover. >>> >> >> Try waterglass mixed with a sealer > > You mean fill the gap with water glass and seal the end with e.g. silicone? > >> Else use fiberglass threads - used on High pressure Nitrogen tanks > > The inner pressure tube must remain visible. Look here: This is a > pressure tube with a polycarbonate protective tube: > > http://darsie.dyndns.org/bernhard/ebay/co2/dsc_0368.jpg > > This is a 60 mm OD, 7 mm wall protective glass tube breaking at a test > explosion: > > http://darsie.dyndns.org/bernhard/CO2/co2.mp2.mp3lame.mpg (4.4 MB) > http://darsie.dyndns.org/bernhard/CO2/co2.avi (3.4 MB, same video, > higher compression) > > Bernhard It seems that part of your problem is solved by manufacturers of current transparent armor systems (multi-layered glasses + polymers). Try to Google "transparent armor" and you'll have some good ideas. You will be able to find out the most mechanically resistant glasses & glass-ceramics in use in that market. See for instance materials like BOROFLOAT�, ROBAX� (SCHOTT), Vycor (Corning Inc.), TransArm (Alstom UK Ltd) and similar. Beside widely used polycarbonates, the polymers currently candidates as component to compose multilayered transparent armor systems are mostly transparent nylons, polyurethane and acrylics. Polyurethane seems to be the best but in order to have something with good optical properties see Simula Polymer Systems Inc for instance. Hope that could help.
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