Effervescence at depth

[SteveAD]

I've once taken an open plastic beverage bottle down, filled it with air at 20m, sealed it and sent it up with the buoyline. Again, I was somewhat underwhelmed with the results as the bottle did not deform or anything but was just very hard. I'd like to repeat that experiment some time from 50m or so but it'll be a few years before I get to dive to that depth.

It is much more interesting to take an empty, capped drink bottle down. It'll squash flat. Ping pong balls are fun too.

 

[ClayJar]

By the way, regarding the "full bottle of air ascending from depth" experiment, here's a little background from a home soda maker (I wear many hats).

There is a note in the article "Carbonating at Home with Improvised Equipment and Soda Fountains" which says, "Compare this to Coca Cola's standard of 3.7 volumes for their bottled product." Let's take that as our benchmark for fresh carbonated beverages. The unit "volumes (of CO₂)" is not common outside the beverage industry. A carbonation level of one volume of CO₂ basically means that each liter of soda has one liter of CO₂ dissolved in it. (It's just a unit of convenience. :biggrin

So, how do you convert volumes of CO₂ into something more useful? Well, you could use some lovely complicated formulas, but most of us just use a simple solubility table... and I just happen to have a CO₂ solubility chart (PDF) right here. You probably don't need to be told that CO₂ solubility in water is a function of temperature and pressure. Solubility (in volumes) is the body of the table, temperature (in degrees Fahrenheit) is the vertical scale, and pressure (in PSI, gauge) is the horizontal scale.

So, if we know that our bottle of Coke has 3.7 volumes of CO₂, we can see what pressure will result from any given temperature. For example, at an almost ice-cold 34 degrees Fahrenheit, the pressure will be something like 19 psi. If we happen to be ice diving with our Coke, and we open it at 34 degrees Fahrenheit and 45 feet depth, there will be no fizz at all.

Anyway, so what if we leave the Coke in the car while we go get tanks filled on the way home? Let's say that the Coke in the bottle gets up to a not-very-delicious 90 degrees Fahrenheit. According to the table, then, the pressure inside the bottle would be around 73 psi (gauge). In my copious experience with hot soda (hey, this is Louisiana), I've never had a bottle burst due to being left in the car. At a mere 90 degrees Fahrenheit, the pressure is equivalent to filling the bottle with air and sealing it at about 164 feet (roughly 50 meters) and sending it to the surface.

A quick Google search ([google]burst pressure soda bottle[/google]) mentions (among many other things) a 120 psi burst pressure for a two liter soda bottle. That would be somewhere around 270 feet or about 82 meters depth for the fill-release-and-boom thing to work. (I haven't put a pressure gauge to a bottle while doing the "dry ice bomb" experiment, as that is *quite* a dangerous an experiment to begin with, but it'd be interesting -- although the thermal effects may be a confounding factor.)

Oh, and in case any of you want to use soda as a fun diversion, here's a little table (made from the 3.7 volumes assumption). For a given temperature, if you open the soda deeper than the listed depth, it should not fizz (regardless of how much you've shaken it):

Temp(F)|PSI(g)|Depth(fsw)
85|67|150
80|62|139
75|56|126
70|50|112
65|45|101
60|40|90
55|36|81
50|32|72
45|27|61
40|23|52
35|20|45

(Oh, and as for my sodas... I carbonate them to about 5 volumes, which is sting-your-mouth fizzy. Anything else tastes flat to me now. )

 

[Guba]

That's why I use a ziploc bag instead of a bottle. That little rascal will expand and burst and, though not as dramatic as a plastic bottle, it will produce a satisfying cloud of bubbles when it releases.

 

[DandyDon]

Haha, blow up a balloon to quart size at 100 ft, hang onto the mooring line well for your ascent, take pics at 66, 33, and surface if it lasts.

 

[paradicio]

YouTube - Under water egg experiment

Crack me up. Towards the end of the video you can hear someone laughing into their reg...

 

[almitywife]

cool thread and posts so virtual "Thanks" button to all!

 

[Deefstes]

Yeah, there's been some brilliant responses in this thread, thanks to all. I couldn't resist, so I watched the "eggsperiment" and it's way cool. I'm gonna do that on my next dive.

Thanks for the nice "thesis" on carbonation ClayJar. That's definitely something I'll also check out. I think I'm going to take a closed carbonated drink down with me and open it at depth. Unfortunately my OW qualification doesn't allow me to take it down to 30m where, theoretically, it shouldn't fizz (if the water is around 20 celcius). However, I think it'll be interesting to take it down to 20m, open it and then ascend. I can imagine that the drink will fizz very little at 20m and generate more bubbles as you get closer to the surface.

You probably found this Youtube clip but I'm adding it 'cause it's interesting. To me it's of particular interest to note that the bottles actually deform very little before they fail and some of the bottles only fail at 12 Bar or higher (that's a whopping 110msw). So I think your experiment of dissolved CO₂ will be much more interesting.


Also, I'm going to try the ziploc bag idea. That's a nice and easy experiment to do.

Jeepers, you'd think that diving isn't enough fun as it is already!

 

[DandyDon]

"To me it's of particular interest to note that the bottles actually deform very little before they fail..." Simply put: The bottles are made from plastic designed to not stretch, while they are designed strong - too strong. There is a raft the size of Texas made of such in the Pacific.

 

[ClayJar]

You probably found this YouTube clip but I'm adding it 'cause it's interesting.

There's one thing I'd point out about that YouTube clip. You may or may not have noticed that the bottles were almost completely full of water. As you know, water is all but incompressible. By filling the bottles with water and only having a small amount of gas as a pressurant, the explosive force is *vastly* reduced.

Doing the same experiment with dry bottles can easily result in sharp-edged plastic "shrapnel" capable of inflicting serious injury. The water-filled bottles stayed roughly in the same place, while dry bottles can send fragments quite a considerable distance. (I wouldn't want to be in the same yard as a dry bottle burst experiment unless I had a "bunker" to hide behind.) The report from a dry bottle burst is also extremely loud, similar to gunfire or decently sized fireworks.

If you have a pool available, sinking the bottle in a reasonable depth may allow you to watch more safely, but obviously, DO NOT watch from inside the pool.

 

[ScubaSteve]

Gotcha. Somthing like:

I think I dove with this person once on a dive boat.