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I've heard some conspiracy theorists claim that if you were to bring a soda can or a bad of chips onto an airplane, they would pop?

Is this true? If so, why?

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closed as off-topic by DeltaLima, fooot, ymb1, kepler22b, Jamiec Jul 18 '18 at 7:27

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "This question does not appear to be about aviation, within the scope defined in the help center." – DeltaLima, fooot, ymb1, kepler22b, Jamiec
If this question can be reworded to fit the rules in the help center, please edit the question.

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    $\begingroup$ Anybody can observe that the food service on aircraft includes soda cans and bags of chips, some of which seem a bit bloated but don't actually "pop". $\endgroup$ – Greg Hewgill Jul 16 '18 at 2:00
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    $\begingroup$ Reddit TIFU of the year $\endgroup$ – Noah Krasser Jul 16 '18 at 6:57
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    $\begingroup$ At school we put soda cans into vacuum chambers, nothing happened. Bag of chips at high altitudes puff up extremely but I think that its the extra pressure of grabbing them that makes them pop (had that happen to me once). Soda cans should be stable enough to withstand a lot more abuse, sometimes even if you want you can't make them pop by throwing them at the ground. $\endgroup$ – PlasmaHH Jul 16 '18 at 8:17
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    $\begingroup$ Conspiracy theorists?... Telling you that soda cans and chip bags should burst?... And, the fact that commercial airline galleys are stocked with cans of soda and bags of chips that don't burst proves... some nefarious plot? $\endgroup$ – Solomon Slow Jul 16 '18 at 16:56
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    $\begingroup$ Something not mentioned is things put in the cargo hold. Many people think the cargo hold is unpressurized and that therefore chips or soda in there would be exposed to the low pressures at 35,000 feet. However, the hold is pressurized (though not usually heated), because it's easier to pressurize a cylinder than a "D" shape (the cabin with a flat floor), so anything in the answers should apply to the hold as well. $\endgroup$ – Skyler Jul 16 '18 at 17:57
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Not likely. Consider how food products normally make it to you.

Any competent US maker of soda or chips will design their product to be shipped

  • on Interstate 70 or 80, via Sherman Summit (8650') or the Eisenhower Tunnel (11,158')
  • or more likely by rail, via again Sherman Summit (8015') or Moffat Tunnel (9239').*
    Aircraft are pressurized to a pressure altitude of 8000' typically, so Sherman Summit (rail).

If a food manufacturer were to botch their packaging, they wouldn't have your problem of a soda can bursting, they'd have an entire container load of sodas or chips burst and ruined for sale. That is simply unacceptable, so manufacturers have a big incentive to get this right.

Other markets will have similar issues - the EU has the Alps, and China and India have the Himalaya. It does not apply to regional sellers in flatland areas, so a regional/indie Florida chipmaker, all bets are off.

It does, however, apply to soda manufacturers, whose cans must endure extreme temperature (e.g. solar loads in a car) also in high places.


* Tennessee Pass (10221') doesn't count, it is weedgrown, rusty and cut in several places, being held for future capacity needs.

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    $\begingroup$ Shaking a can of soda doesn't significantly increase its internal pressure, and doesn't make it more likely to burst. A shaken can of soda explosively foams after opening because of the large number of nucleation sites, not increased pressure. $\endgroup$ – Sneftel Jul 16 '18 at 9:33
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    $\begingroup$ Sankt Moritz is only at 6000 feet. As for tunnels, the (old) Gotthard tunnel in the Alps is only at 3600 feet, which is pretty typical. In fact, the new batch of Swiss tunnels is even lower, it's been nicknamed Swiss Metro. Furthermore, unlike the Rockies, it's often easier to ship something around the Alps. $\endgroup$ – MSalters Jul 16 '18 at 10:58
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    $\begingroup$ This is just wrong. Potato chip manufacturers actualy make different production runs for different destinations. Chips that are specifically destined for in-flight airline use or are intended for shipment over mountain locations (ie: to the US west coast) are filled with slightly less air and, in the latter case, are shipped in special containers with sealed polymer liners inside the cardboard shipping carton to help keep a higher pressure around the bags, if needed. Where possible, high altitude shipment routes are avoided. The unprotected individual bags can certainly pop at altitude. $\endgroup$ – J... Jul 16 '18 at 13:37
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    $\begingroup$ @mbrig Actually, it seems not that hard : My Worst Load Ever: Hauling Oregon Potato Chips to Texas $\endgroup$ – J... Jul 16 '18 at 14:40
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    $\begingroup$ @jamesqf Then your chip bag will pop. It happens all the time. $\endgroup$ – J... Jul 16 '18 at 16:52
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I can confirm that bagged snacks can pop from the pressure difference. Climbing through 7,000 feet (on our way up to 9,000) in an unpressurized PA32 we heard a quite loud POP. In and out of clouds at the time we were busy in the front seat, didn't observe any flight control or systems issues. Fortunately had a person in the back that looked around there for us. After trying to look outside at airplane surfaces for awhile she turned her attention inside and found a bag of popcorn (the already popped, snack style) had exploded...

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    $\begingroup$ This has happened to me as well. it's happened to me climbing at about 12,000 feet, flying GA aircraft at about 10,000 feet and once driving over a mountain pass at about 8,500 feet. $\endgroup$ – David Schwartz Jul 17 '18 at 18:47
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I brought a bag of chips on a Quantas A380 flight recently and it ruptured during ascent. Sitting very close to the bag, I thought the sound was quite loud. Nobody else noticed it. Results may vary from bag to bag.

Chip bags are pressurised relative to the atmosphere. As the plane climbs, the pressure in the cabin drops, which increases the pressure difference. This pressure difference may exceed the strength of the bag, causing it to break.

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    $\begingroup$ purely anecdotal stories can help make a point, but aren't enough. The bag could have ruptured for any number of reasons. $\endgroup$ – jwenting Jul 16 '18 at 5:32
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    $\begingroup$ @okolnost "during takeoff", the plane is pretty close to ground level. If you had said "shortly after takeoff" that might have been convincing. $\endgroup$ – Martin Bonner Jul 16 '18 at 7:48
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    $\begingroup$ @Ister Are you saying that there are pumps in the aircraft which can lower cabin pressure below ambient? That seems extraordinary to me. $\endgroup$ – Martin Bonner Jul 16 '18 at 12:44
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    $\begingroup$ @Ister: Second that comment. You're essentially claiming that airplanes have hardware on board which is totally unnecessary, but does add extra weight AND electric risks? Airplane hulls are designed for overpressure (tensile load), not underpressure (compression load). $\endgroup$ – MSalters Jul 16 '18 at 13:57
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    $\begingroup$ @Ister, pilots (or the automatic system) don't set pressure in the cabin, they set the schedule of pressure change. As it happens, after the cabin is sealed, the pressure is typically increased slightly, making it higher than ambient (i.e: 'negative' cabin altiture). $\endgroup$ – Zeus Jul 16 '18 at 14:13
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Soda cans are designed to withstand much larger amounts of pressure from the inside. Ever tried to squeeze a soda can that has just been shaken? Taking away outside pressure can only increase the inside pressure by 1atm - and that would mean placing the can in a vacuum. Simply shaking a can will increase the inside pressure much more than that and a can is supposed to survive even more than just shaking. You can make a soda can burst by heating it up, but that'll require quite a bit of heat.

Bags of chips are not designed to withstand large amounts of inside pressure because chips to not generate any pressure like a carbonated liquid does. Depending on the pressure at the time of packaging and the packaging itself, they usually do "inflate" a bit on a flying aircraft and in rare circumstances they may even burst.

[edit]I decided to dig out some numbers, so here we go:

https://hypertextbook.com/facts/2000/SeemaMeraj.shtml

A cooled soda can have an internal pressure as low as 1atm (~100kPa) up to more than 2atm.

At room temperature this goes up to around 4atm.

So taking a can out of the refrigerator and putting it on the table increases the pressure more than placing a (cooled) can inside a vacuum.

As has been pointed out in the comment, shaking may not significantly increase pressure. (I was expecting a more than minor increase because a bottle that has recently been shaken certainly feels "harder", but OTOH you need to be really careful when it comes to "feeling" things like pressure!)

Temperature, however, does increase pressure significantly and I would expect a soda can to be designed to withstand the pressure of a hot summer day in the shade - i.e. 40°C/100°F. (It's not trivial to predict the pressure at that temperature, so I'm not trying.) [/edit]

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  • $\begingroup$ Copying Sneftel's comment on another answer: Shaking a can of soda doesn't significantly increase its internal pressure, and doesn't make it more likely to burst. A shaken can of soda explosively foams after opening because of the large number of nucleation sites, not increased pressure. $\endgroup$ – Henning Makholm Jul 16 '18 at 12:34
  • $\begingroup$ I've personally seen a galley get covered in soda when a flight attendant tried to open a can and it ruptured instead. I would call that an "explosion". Not saying a one-off observation suggests that such things have a non-trivial probability of occurring, but they certainly "can". $\endgroup$ – supercat Jul 16 '18 at 16:09
  • $\begingroup$ To add to the last paragraph, I've recently been the 'victim' of a can left in a car on a hot day. The can didn't spontaneously explode. However as soon as I pulled the tab slightly, the 'ring pull' area of the can top (which normally would fold inside the can) was blown clean off the can, hitting my hand painfully on the way. It only took a very small break at a weak point for it to fail instantly. $\endgroup$ – Graham Jul 16 '18 at 22:26
  • $\begingroup$ Just for what it's worth, a friend of mine use to work at a bottling plant. As I recall, he said 1 liter bottles can pretty routinely hold up to about 100 PSI, and 2 liter bottles around 80 PSI. In both cases, they're pretty much globe shaped (other than the neck/top of the bottle) before they burst. He didn't deal with cans though, so I don't have any solid data on what they'll withstand. $\endgroup$ – Jerry Coffin Jul 17 '18 at 23:06
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I have never had a bag of chips pop in a commercial flight (although I've had bags that seemed to be right on the verge).

On the other hand, in a single engine non pressurized Beechcraft Bonanza we had a bag of chips explode in the cabin as we were climbing to our cruising altitude. It's been too long for me to remember our altitude, but it can and does happen. Scared the crap out of me as it was near me when it happened and it was quite loud.

Can of soda? Haven't had one explode in the air. I have had cans of soda explode due to heat though in the summer in the trunk of my car, on several occasions. Luckily in my case they were all seltzer water.

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The only reason it might pop is if the cabin pressure were to suddenly disappear. That's explosive decompression and if it happens you've more serious problems than having some soda or crisps soil your clothes or whatever is in the bag it popped in.

I did once get the advise to open any cans or bottles containing carbonated drinks I was planning to consume during a flight before takeoff, but that was on board an old Soviet era aircraft with a faulty pressure cabin. In such cases the sudden release of pressure can cause the liquid to spill out, similar to shaking a bottle of soda violently before opening the lid would do on the ground (or, as my aunt once did mistakenly, freeze cans of soda so they'd be nice and cold for next day's road trip, then leaving them out in a hot car where they built up so much pressure they ruptured).

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    $\begingroup$ How and why were you flying on anything with a "faulty pressure cabin"? xD $\endgroup$ – Cloud Jul 16 '18 at 6:25
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    $\begingroup$ @Cloud Siberia, 1980s, Aeroflot An-24. Was the only available aircraft at the field we'd made an emergency landing on in a Tu-154 the previous day. $\endgroup$ – jwenting Jul 16 '18 at 6:59
  • $\begingroup$ well, now you'll have to go to North Korea to fly on a tu154, if yuo have a death wish :) $\endgroup$ – Cloud Jul 16 '18 at 7:33
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Definitely. I have seen it on older aircraft at medium altitude chips bags can pop easily. Altitude at which no cabin pressure is even required.

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