114
votes
Why do glass windows still exist? (Why haven't they been replaced by plastics?)
There are two main reasons why glass is still preferred over say PMMA.
The first is durability. As long as it isn't broken, the glass in a window can easily last for hundreds of years in good ...
- 15.1k
46
votes
Why do glass windows still exist? (Why haven't they been replaced by plastics?)
Here is a plastic (most likely PMMA) window, in a boat, after only 37 years.
In addition to the obvious scratches, the outer surface has developed a cloudiness : possibly from degradation due to ...
- 1,610
31
votes
Why do glass windows still exist? (Why haven't they been replaced by plastics?)
What are the requirements for window glass?
Resistance to moisture
Resistance to UV radiation
Resistance to cleaning agents
Very high transmission in the visible spectrum
(There are many more, from ...
- 1,618
15
votes
Why do glass windows still exist? (Why haven't they been replaced by plastics?)
I actually did make windows out of plexiglas for an outbuilding. I could work them to the shape I wanted and they were lightweight. However, I discovered that they indeed scratch easily: just trying ...
- 257
14
votes
Can the Sabatier reaction power a vehicle?
According to Wikipedia:
It [Sabatier reaction ] involves the reaction of hydrogen with carbon dioxide at elevated temperatures (optimally 300–400 °C) and pressures in the presence of a nickel ...
- 2,160
13
votes
Accepted
What does "a" mean at the end of a refrigerant's designation (R-134a)?
R134a..Here "a" is used to denote that it is an isomer. R134 and R134a have same chemical formula and atomic weight but different chemical structures.
R134 has NBP of about -19 C whereas ...
- 538
10
votes
Why do glass windows still exist? (Why haven't they been replaced by plastics?)
After some research,
we are using glass windows as it was used traditionally. Actually plastic windows exists. Though it may take time for most of us to adapt to it.
While the reasons to consider ...
- 585
7
votes
Why do glass windows still exist? (Why haven't they been replaced by plastics?)
Another issue is that the coefficient of thermal expansion of many plastics is higher than that of window glass. Frames for plastic windows would have to be able to accommodate more expansion / ...
- 71
6
votes
Can current passing through a wire potentially ignite gasoline? If not, why?
For a combustible mixture to ignite, it must be within its flammability limits. This forum provides an anecdotal explanation for gasoline's inflammability in an automobile tank:
...when the tank is ...
6
votes
P&ID Symbol identification, unknown meaning
This is an instrument symbol, they are read in the following way,
ISA Symbology
The symbology of the instrument it is placed in a circle of 7/16 “or 12 mm (see below), was in the top there is ...
- 699
6
votes
Is there a maximum life for things made out of stainless steel or cast iron?
Strictly speaking, very few metals are "stable" in terms of the laws of thermodynamics. True chemical stability is when the atoms are in their lowest energy state. For most metallic elements,...
- 181
5
votes
How does conductivity $\sigma$ of salt-water depend on salinity?
Measuring the conductivity of water is actually one of the standard ways of measuring its salinity. The figure below (taken from this University of British Columbia page) shows that the relationship ...
- 6,386
5
votes
Accepted
Cleaning anodised aluminium
Chuck is right that there could be some galvanic action contributing to your issue. One other possibility is that your aluminum has been contaminated with steel particles at some point. Your second ...
- 4,511
5
votes
What relationship is there between mass of water vapour produced in combustion and the energy lost through producing this water?
If you get complete combustion of any hydrocarbon fuel, your products will be primarily $CO_2$ and $H_2O$. Other products will be present in quantities too small to be relevant to the heat losses that ...
- 1,966
5
votes
Exploiting fluid dynamics for the optimal design for gas mixing in a furnace
As far as I understand your question you are looking for a way to diffuse/mix two gases into each other. The process is very hard to simulate "correctly" because of the characteristics of the ...
- 1,192
5
votes
How to determine if mass transfer convection is natural or forced?
The Richardson number $\mathrm{Ri} = \frac{\mathrm{Gr}}{\mathrm{Re}^2} = \frac{\text{buoyancy term}}{\text{flow gradient term}}$ (1) can be used to determine if forced or natural convenction dominate ...
- 1,734
5
votes
Accepted
How do temperature and pressure influence the rate of evaporation of water in a closed vessel?
$\frac{1}{22.4}\frac{\mathrm{mol}}{\mathrm{L}}$ is only valid for standard conditions. Use the ideal gas law to calculate the concentration for your conditions.
$s \equiv$ standard conditions
$2 \...
- 1,734
5
votes
Why do we still scuba dive with bottled air?
Bottled air is used for SCUBA because it is simple, reliable and relatively inexpensive and an open circuit system with a demand valve is pretty safe to use.
There are closed circuit systems (...
- 15.1k
5
votes
Accepted
Nylon brittleness as function of moisture content
Nylons are a class of polymers formed from di-acid and di-amine monomers. The amine groups bond with the acid groups to form amide groups, end to end. The resulting amide groups have a positive charge ...
- 4,031
5
votes
Why lead was chosen as the metal for lead-acid batteries?
each electrochemical reaction involving a lead atom in a lead-acid cell releases two electrons into the external circuit, which means it has a relatively good extractable power-to battery mass ratio. ...
- 13.5k
5
votes
How can I vaporize metals?
The easiest way to vaporize a metal is to create a filament of the metal. Heat the filament in the vacuum to its sublimation (vaporization) temperature. Alternatively, when the metal cannot be shaped ...
- 2,868
4
votes
Exploiting fluid dynamics for the optimal design for gas mixing in a furnace
Preliminary results
I added a conical structure before the choking point to separate the flow. Basically cutting the fluid. This cone is attached with 4 supports. This configuration increased ...
- 331
4
votes
Accepted
What are the advantages of chemical oxygen generation over compressed tank storage?
One advantage these chemical systems may have over compressed tanks is how well they are suited for intermittent use and long-term storage (as opposed to regular, continuous operation). The US FAA ...
- 3,211
4
votes
What are the advantages of chemical oxygen generation over compressed tank storage?
From personal experience of refuge systems, oxygen generating systems are preferred over medical oxygen gas tanks because of space requirements, portability and the ease of relocation.
When emergency ...
- 9,527
4
votes
Accepted
How to separate isotopes of Plutonium?
Pu238 is not usually isotopically separated from spent nuclear fuel for exactly the reason you pointed out, it would be very difficult. Instead most of what we have comes from one of two different ...
- 716
4
votes
Why can we neglect the inertial (but not viscous) term in Navier-Stokes at low flow and high viscosity?
Usually what is implied by low flowrate and high viscosity is that we are dealing with a so-called low Reynolds number flow. The Reynolds number is dimensionless number which is the ratio of inertial ...
- 167
4
votes
Why do glass windows still exist? (Why haven't they been replaced by plastics?)
Hardness aside, weathering effects (from e.g. rainfall, snow, hail, temperature and moisture variations etcetera) and UV degradation are of course important to consider for windows. In general, glass ...
- 41
4
votes
Heat Exchanger Design - finding necessary variables
I found the average of the inlet and outlet pressure and temperature in the hydrocarbon stream and then used those values in the ideal gas equation to find the densities of each hydrocarbon
Why would ...
- 2,160
4
votes
How to hermetically seal a circuit in a visual & bluetooth transparent solid cube ~2-3"?
The process of encasing electronics in a material is called potting.
Various resin materials can be used, such as polyester resin or epoxy. Discussion of the types of resin can be found in this ...
- 198
Only top scored, non community-wiki answers of a minimum length are eligible