Mailing List Archive Mailing List Archive
At 02:39 PM 4/20/99 -0700, Mat Bloedorn wrote:
>You have to remember that we are talking about
>heating a gas that is inside a fixed chamber (the
>tank)
>in this case heating the gas causes an increase in
>pressure.
Exactly. And as it turns out, the gas in a cylinder
at 3500 PSI is about 43% a viscous as water. I'm
attaching my original viscosity post for clarity.
===============================================
This thread got me thinking about why the gasses in a cylinder
might not mix thoroughly during the filling process and I
came up with an interesting result. If you find an error,
please be gentle with me... it's late as I write this. 8-)
Viscosity is usually measured in the SI unit poiseuille with
dimension of newtons*sec/m^2. I looked up the numbers,
plugged them in and got 1.0*10^-2 for water and 1.8*10^-5 for
air. Then, I multiplied the figure for the viscosity of air
by 238 (~[3500/14.7] the number of atmospheres at 3500 PSI)
and got 4.3*10^-3. So, we have:
Water = 10.00 millipoiseuille
Air at 3500 PSI = 4.32 millipoiseuille
That means (if I didn't mess up) that, while air at sea level
pressure is one tenth of one percent the viscosity of water,
pressurized air at 3500 PSI is over 43% as viscous as water;
that's pretty thick. No wonder it doesn't mix well on its
own.
BTW, one very interesting thing about viscosity is that,
with increasing temperature, viscosity decreases in
liquids, but increases in gases. All the more reason
to fill slowly.
================================================
-Mike Rodriguez
<mikey@ma*.co*>
--
Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'.
Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
Navigate by Author:
[Previous]
[Next]
[Author Search Index]
Navigate by Subject:
[Previous]
[Next]
[Subject Search Index]
[Send Reply] [Send Message with New Topic]
[Search Selection] [Mailing List Home] [Home]