# Why 15 psi max on pressure cookers? **URL:** \ **Category:** Factual Questions\ **Created:** [December 30, 2006, 10:20pm UTC](https://boards.straightdope.com/t/why-15-psi-max-on-pressure-cookers/386149 "2006-12-30T22:20:14Z")\ **Posts on this page:** 4\ **Page:** 3
**Author:** ![Bill\_Door](https://avatars.discourse-cdn.com/v4/letter/b/50afbb/32.png) [@Bill\_Door](https://boards.straightdope.com/u/Bill_Door)\ **Post date:** [October 23, 2015, 3:01pm UTC](https://boards.straightdope.com/t/why-15-psi-max-on-pressure-cookers/386149/41 "2015-10-23T15:01:49Z")
> [@Leo\_Bloom](#): > > I don’t understand what is meant by “pressure stored,” even though experientially that is as good a way as any to describe it. But it seems kind of just-so-ish. > > Before I go off to Wiki “compression,”–which is where I think I should go–after which I’ll probably come back anyway, can someone put “storing pressure” into some more discrete terms? > > Also, I’m guessing here, as well the thermodynamic aspects under discussion here, does the term “continuum mechanics” apply to the area of physics I think I’m getting at? > > - off to check what c.m. means while he’s there… \* That’s not really a good description. What they mean is that water inside the kernel has been heated above the boiling point at atmospheric pressure. This water has remained in the liquid phase because the external pressure around the kernel has been raised high enough to prevent boiling. When this external pressure is released the water inside the kernel flashes, or turns almost instantaneously into vapor, increasing the volume by a factor of around 1,600. ---
**Author:** ![Dag\_Otto](https://avatars.discourse-cdn.com/v4/letter/d/439d5e/32.png) [@Dag\_Otto](https://boards.straightdope.com/u/Dag_Otto)\ **Post date:** [October 24, 2015, 10:48pm UTC](https://boards.straightdope.com/t/why-15-psi-max-on-pressure-cookers/386149/42 "2015-10-24T22:48:11Z")
> [@Bill\_Door](#): > > That’s not really a good description. What they mean is that water inside the kernel has been heated above the boiling point at atmospheric pressure. This water has remained in the liquid phase because the external pressure around the kernel has been raised high enough to prevent boiling. When this external pressure is released the water inside the kernel flashes, or turns almost instantaneously into vapor, increasing the volume by a factor of around 1,600. I was wrong about the 7000:1 ratio. It is about 1600:1. ---
**Author:** ![FluffyBob](https://avatars.discourse-cdn.com/v4/letter/f/ecb155/32.png) [@FluffyBob](https://boards.straightdope.com/u/FluffyBob)\ **Post date:** [October 25, 2015, 8:41pm UTC](https://boards.straightdope.com/t/why-15-psi-max-on-pressure-cookers/386149/43 "2015-10-25T20:41:33Z")
Which brings us of course to the [Mythbusters Chinese Popcorn canon](https://www.youtube.com/watch?v=baQT0pwvXKQ) Bonus points for special guest Alton Brown. Its not your standard Pressure Cooker, but hey its a pressure cooker. I get 145 psi for 1 MPa, so that gets you over that pesky 15 psi limit. I don’t think they carry it at Walmart. ---
**Author:** ![PlumBob](https://avatars.discourse-cdn.com/v4/letter/p/ee59a6/32.png) [@PlumBob](https://boards.straightdope.com/u/PlumBob)\ **Post date:** [October 27, 2015, 4:31pm UTC](https://boards.straightdope.com/t/why-15-psi-max-on-pressure-cookers/386149/44 "2015-10-27T16:31:17Z")
This guy has an interesting blog entry on higher pressure, pressure cooking [http://www.cookingissues.com/2011/08/12/voiding-your-warranty-hacking-electric-pressure-cookers/](http://www.cookingissues.com/2011/08/12/voiding-your-warranty-hacking-electric-pressure-cookers/) [Previous page](https://boards.straightdope.com/t/why-15-psi-max-on-pressure-cookers/386149.md?page=2)