[Beowulf] Swimming in oil..

Tim Cutts tjrc at sanger.ac.uk
Mon Feb 11 16:30:42 PST 2019


The Dead Sea is so buoyant it makes swimming rather difficult. Floating on your back is about all that's possible. I learned the hard way not to attempt swimming on your front. Your backside pops out of the water and the resulting rotation shoves your face into it.

And that salinity *hurts*.

Tim

Sent from my iPhone

> On 11 Feb 2019, at 11:40 pm, Lux, Jim (337K) via Beowulf <beowulf at beowulf.org> wrote:
> 
> Dead Sea 1.24 g/cc
> Great Salt Lake 1.17 g/cc (depending on where you are and the time of year - right now it's partly frozen, so the density is higher)
> Seawater 1.03 g/cc. (it's not all that salty)
> Glycol/water mixtures - up to 1.07 g/cc
> Scotch whisky - 0.94 g/cc. (you'd best not be trying to swim ..)
> 
> As for a butt of malmsey?  - a butt isn't that big, so the Duke of Clarence probably wasn't swimming on 18 Feb 1478.
> 
> I suspect he was immersed head first, much like Stu into the vat of oil.
> 
> 
> 
> ´╗┐On 2/11/19, 3:19 PM, "Robert G. Brown" <rgb at phy.duke.edu> wrote:
> 
>>    On Mon, 11 Feb 2019, Lux, Jim (337K) via Beowulf wrote:
>> 
>> Stu reports swimming, but perhaps he was really more wading.
> 
>    A beautiful summary below.  I should keep it to use with my students
>    when we cover Archimedes' Principle and buoyancy.  I hadn't even thought
>    about this danger from dealing with large tanks of low density fluid,
>    but it makes sense -- you can drown in CO2 if you go down in a crater
>    full of CO2 because you don't float to the top and surely can't swim to
>    the top...
> 
>    OTOH, in the Dead Sea or the Great Salt Lake (or even just the
>    Mediterranean) the density is greater than that of fresh water, and it
>    is correspondingly easier to tread water or swim, harder to drown.  I
>    don't think you could "drown" in a well-ventilated vat of mercury unless
>    you deliberately rolled face down on it, although breathing in the
>    mercury vapor over its surface would certainly be a problem.
> 
>    Very nice!
> 
>        rgb
> 
>> 
>> 
>> A significant problem with large vats of liquid, whether used for cooling
>> electronic equipment, or just storage, is that if the density is
>> significantly less than that of water, you don?t float. Humans are just
>> slightly positively buoyant in water (with full lungs). Change that to oil
>> or corn syrup or scotch whisky with a density of 0.9, and it?s like having
>> 5-10 kg of weight on you, and that takes a lot of work to stay on the
>> surface.
>> 
>> This is a well known hazard in the petroleum processing industry (aside from
>> the fact that the air above the tank?s liquid surface is probably full of all
>> manner of unhealthy things and not oxygen) ? you fall in the big tank, you
>> die.
>> 
>> 
>> Diala AX (a HV insulating oil I?ve used) has a specific gravity of 0.885, and
>> is somewhat more viscous than water (not a lot) ? if you fell into it, and
>> couldn?t support yourself by standing on the bottom or equipment within the
>> tank, you?d need to be rescued pretty quickly. The increased viscosity would
>> also mean that it?s more work to keep ?treading oil? to stay above the surface.
>> 
>> 
>> USP white mineral oil is about 0.85 g/cc. We had a thousand gallon tank of
>> this where I used to work, and there was a whole discussion about safety ? it
>> was a wide flat tank, so in theory, if you fell in, you could stand up
>> (except that the tank was polyethylene and it *is* oil.. there were
>> questions about whether you could stand up on the slippery surface)
>> 
>> 
>> Of course, you can get oil in all densities ? the stuff they use for road
>> surfacing is quite dense.
>> 
>> 
>> 
>> Fluorinert FC-40 (which I?ve also used) is quite dense ? 1.85 g/cc ? you?d float
>> well above the surface like a cork. A quick glance at the line card for Novec?
>> shows they?re all pretty dense - 1.4g/cc is the least dense.
>> 
>> 
>> --
>> 
>> 
>> 
>> 
> 
>    Robert G. Brown                           https://urldefense.proofpoint.com/v2/url?u=http-3A__www.phy.duke.edu_-7Ergb_&d=DwIGaQ&c=D7ByGjS34AllFgecYw0iC6Zq7qlm8uclZFI0SqQnqBo&r=gSesY1AbeTURZwExR_OGFZlp9YUzrLWyYpGmwAw4Q50&m=_p0FUqzSWJ7HwtLx0yAJDwHyOjz-3P9z_57CSziq3fw&s=h6uxnIWBwG1oIcqSJevLqy2FN5bjTNO6oaL0nnubdyE&e=
>    Duke University Dept. of Physics, Box 90305
>    Durham, N.C. 27708-0305
>    Phone: 1-919-660-2567  Fax: 919-660-2525     email:rgb at phy.duke.edu
> 
> 
> 
> 
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