# Question about keg pressure and punctures
**URL:** https://boards.straightdope.com/t/question-about-keg-pressure-and-punctures/121250
**Category:** Factual Questions
**Created:** [July 28, 2002, 4:46pm UTC](https://boards.straightdope.com/t/question-about-keg-pressure-and-punctures/121250 "2002-07-28T16:46:17Z")
**Posts on this page:** 9
**Page:** 1
### Author:  [@Flypsyde](https://boards.straightdope.com/u/Flypsyde)
#### Post date: [July 28, 2002, 4:46pm UTC](https://boards.straightdope.com/t/question-about-keg-pressure-and-punctures/121250/1 "2002-07-28T16:46:17Z")
Having seen the results of a hot and shaken beer getting punctured, I’ve been wondering if the same could happen to a keg.
Let’s say, for instance, I’ve got a keg that’s been slamming around in the back of a truck and has been rolled down a flight of stairs. Then let’s say someone shoots a crossbow bolt at it.
1. Will the bolt even penetrate it?
2. If the bolt will, what would the result be? I mean, is a keg constructed such that the escaping pressure and beer could propel the keg a fair distance?
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### Author:  [@Duck\_Duck\_Goose](https://boards.straightdope.com/u/Duck_Duck_Goose)
#### Post date: [July 28, 2002, 7:12pm UTC](https://boards.straightdope.com/t/question-about-keg-pressure-and-punctures/121250/2 "2002-07-28T19:12:11Z")
IANA ballistics geek, but–why a crossbow? I’d think that the bolt would penetrate halfway and then get stuck, thereby plugging the hole it just made. In Errol Flynn movies, the crossbow bolts are _always_ getting stuck, although it’s usually in an oaken door, not in a beer keg…
And are you talking about a wooden keg or a steel one?
Seems like a bullet would work better, so now it only remains for the real Ballistics Geeks to show up and tell us how big a gun would be required to blow a hole in the average beer keg.
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### Author:  [@DougC](https://boards.straightdope.com/u/DougC)
#### Post date: [July 28, 2002, 8:20pm UTC](https://boards.straightdope.com/t/question-about-keg-pressure-and-punctures/121250/3 "2002-07-28T20:20:23Z")
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- As I remember a beer keg is normally under about 30-40 PSI and bursts at around 150-180 PSI. A .22 rinfire from up close would probably go through one side; an arrow would probably stick in the hole. I doubt you’d get much of any explosion because the pressure in the keg is well within its safe range. I know from shooting at small propane tanks that they don’t burst, the bullet just makes a hole that goes “fssssssss” --unless you use incendiary bullets, and even then the tank doesn’t rip open, it just shoots a flame out of the hole. If you used a bigger or faster rifle such as a 22-250 or a .308 the keg might split open from the hydrostatic action but still, I think the gun going off would make far more noise than the keg exploding, just because the liquid inside would have a dampening effect. Nobody I know has ever had the heart to shoot at a full beer keg… You can make a plastic gallon jug basically “explode” by filling it with ordinary water and shooting it with a faster rifle (3000 FPS+).
- A few years ago in my area, two people were killed in two separate incidents a couple weeks apart: the first was at a outdoor party; when after a beer keg was emptied somebody threw it on the fire and it heated up and burst. The second incident was a couple weeks later, also at an outdoor party, where a completely different set of people tried the exact same thing _because they heard about the first incident on the news_. Obviously if you’re detirmined to experiment with exploding beer kegs it’s not something to be standing close by and watching… - DougC
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### Author:  [@Flypsyde](https://boards.straightdope.com/u/Flypsyde)
#### Post date: [July 28, 2002, 8:57pm UTC](https://boards.straightdope.com/t/question-about-keg-pressure-and-punctures/121250/4 "2002-07-28T20:57:49Z")
Huh. I’m a little intrigued by the fact that the only participants in this thread so far are all from Illinois.
Okay, here’s the gist of why I’m asking. I’m writing something, and for authenticity’s sake I’m curious as to whether or not it would be possible for a keg to be propelled any distance by means of its contents. Perhaps shooting the bolt at the valve?
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### Author:  [@RyanV](https://boards.straightdope.com/u/RyanV)
#### Post date: [July 28, 2002, 9:46pm UTC](https://boards.straightdope.com/t/question-about-keg-pressure-and-punctures/121250/5 "2002-07-28T21:46:56Z")
60psi max pressure.
(it says so on my b-day keg) 😉
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### Author:  [@DougC](https://boards.straightdope.com/u/DougC)
#### Post date: [July 28, 2002, 10:11pm UTC](https://boards.straightdope.com/t/question-about-keg-pressure-and-punctures/121250/6 "2002-07-28T22:11:22Z")
> [@](#):
>
> Huh. I’m a little intrigued by the fact that the only participants in this thread so far are all from Illinois.
- Hey, I’m no expert, it’s not like I’m from Michigan or anything. - DougC
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### Author:  [@drachillix](https://boards.straightdope.com/u/drachillix)
#### Post date: [July 28, 2002, 11:10pm UTC](https://boards.straightdope.com/t/question-about-keg-pressure-and-punctures/121250/7 "2002-07-28T23:10:09Z")
> [@](#):
>
> \*Originally posted by Flypsyde \*
> \*\*Huh. I’m a little intrigued by the fact that the only participants in this thread so far are all from Illinois.
>
> Okay, here’s the gist of why I’m asking. I’m writing something, and for authenticity’s sake I’m curious as to whether or not it would be possible for a keg to be propelled any distance by means of its contents. Perhaps shooting the bolt at the valve? \*\*
In a nutshell…no. even if you somehow liberated every little bit of CO2 from the beer you still wouldn’t have enough gas to vent and develop sufficent trust to lift a 40-50 pound object off the ground let alone make it fly. Compressed gas tanks like you get for welding and such are often under 1500-2000 PSI (50-60 times as much pressure)
I wonder what kind of adiabatic cooling you would get dispensing beer at 2000 psi :eek:
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### Author:  [@Chronos](https://boards.straightdope.com/u/Chronos)
#### Post date: [July 29, 2002, 9:11pm UTC](https://boards.straightdope.com/t/question-about-keg-pressure-and-punctures/121250/8 "2002-07-29T21:11:02Z")
OK, in order to move the keg, you’ll need thrust approximately equal to its weight. A keg is what, about 20 gallons? At eight pounds per gallon, that would be a net weight of about 160 pounds. Using **DougC** ’s figure of 40 psi, that would mean that a hole two inches on a side would be necessary to propel a keg.
Briefly. You’ll no doubt appreciate that a keg won’t stay at 40 psi for very long with a two-inch hole in the side.
As for the Illinois thing, Dopers tend to be concentrated in cities which carry the Straight Dope in newspapers, including, of course, the SD’s home town of Chicago.
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### Author:  [@DougC](https://boards.straightdope.com/u/DougC)
#### Post date: [August 31, 2002, 6:51pm UTC](https://boards.straightdope.com/t/question-about-keg-pressure-and-punctures/121250/9 "2002-08-31T18:51:53Z")
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- Okay, I was way off: looking at a few empty beer kegs at the store where I work, they all had something similar to the inscription:
> [@](#):
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> 13.5-17|15
> Container Will Rupture Above 60 PSI.
…so for the record, we may assume the working pressure is only around 15 psi, and 60 psi is the _limit_.
~