About explosion pressure

Harness the power of precision mixtures of pressurized flammable vapor. Safety first! These are advanced potato guns - not for the beginner.
yyt
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Mon Nov 07, 2022 10:33 pm

The air contains 1/5 oxygen. Is the effect of using pure oxygen+propane the same as that of 5 times mixing? Are their pressure peaks the same?
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jackssmirkingrevenge
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Tue Nov 08, 2022 9:18 am

I don't know if anyone has made a specific side by side comparison, but while the ratio of oxygen to propane is the same in both cases, there are important differences.

Working with pure oxygen is a lot more dangerous so it is less practical, and there is a danger of DDT especially at higher mixes. This might cause a dramatic spike in pressure, but will not necessarily result in a more powerful launcher. It's the reason we use relatively slow burning propellants in firearms and not high explosives.

In his tests with the high performance hybrid linked to elsewhere, he noted that he got better and more consistent performance with compressed air as opposed to pure oxygen.
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yyt
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Wed Nov 09, 2022 2:19 am

jackssmirkingrevenge wrote:
Tue Nov 08, 2022 9:18 am
I don't know if anyone has made a specific side by side comparison, but while the ratio of oxygen to propane is the same in both cases, there are important differences.

Working with pure oxygen is a lot more dangerous so it is less practical, and there is a danger of DDT especially at higher mixes. This might cause a dramatic spike in pressure, but will not necessarily result in a more powerful launcher. It's the reason we use relatively slow burning propellants in firearms and not high explosives.

In his tests with the high performance hybrid linked to elsewhere, he noted that he got better and more consistent performance with compressed air as opposed to pure oxygen.
But if my barrel is short, I may choose pure oxygen, because it burns fast enough, and compressed air is more suitable for long barrel. I think the difference is just like a pistol and a rifle. A pistol must use gunpowder with a fast burning rate to accelerate for a short time, while a rifle barrel is long enough to burn fully.
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jackssmirkingrevenge
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Wed Nov 09, 2022 9:41 am

yyt wrote:
Wed Nov 09, 2022 2:19 am
But if my barrel is short, I may choose pure oxygen, because it burns fast enough, and compressed air is more suitable for long barrel. I think the difference is just like a pistol and a rifle. A pistol must use gunpowder with a fast burning rate to accelerate for a short time, while a rifle barrel is long enough to burn fully.
That sounds like it would be logical, personally however I would still be very wary of handling pure oxygen.
hectmarr wrote:You have to make many weapons, because this field is long and short life
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