Engineering with Soda Bottles

[mtimakov]

Hey friends,

I am not a fellow water rocketeer, but I need some help!

I am designing and implementing a fixed air pressure fuel system. So, pump up a pressure tank with up to 5 bars and have it push liquid fuel past several components, like regulators, into a combustion engine. I'm having a little bit of trouble with the design and implementation of the adapter from the pressure tank that will be a soda bottle. I need to make sure that a soda bottle (1-2L) can withstand 5 bars (I know its like a one time use kind of thing, but what about for a few hours?) and I need to modify 2 different caps (fuel tank and soda bottle) so that they can take nylon tubing and properly seal airtight.

I know you guys know your bottles, caps, and fluids pretty well so I'm asking for some help! If you can answer any of these from any experience you have had or similar projects, please let me know!

Thanks

[Mike C]

I'm new here also, and I've noticed the forum is fairly quiet, so until someone more experienced appears, I'll offer my thoughts.

Don't see a problem with 5 bar, I've tested up to 7 with no problems.
But in your situation it may differ as not using water, and may be affected by the environment such as temperature.
For the bottle connection it may be easier - depending on size of hose - to fit it over the bottle neck (maybe with an adapter) and secure with a hose clip.
Or 3d print an adapter, which may be safest as dealing with a combustible material. There are lots of PET bottle adapter files on the web.
Otherwise use epoxy to secure a bottle cap to a garden hose connector and put a hole in the cap, but I don't think I'd trust that if it may engulf me in flames.

Mike

[mtimakov]

The bottle getting up to 7 bar with no problems sounds great. I know that these bottles get brittle once you release them from lots of pressure because of how their structure. The 1 time use thing does not bother me, I do not want this thing blowing up. As for the atmosphere the main factor is temperature which would should be around _____.

I want to clarify that the bottle caps need to be modified, not replaced with an adapter entirely. If an adapter is to be used it would have to fit over the cap and have some kind of gasket fitted, preventing it from leaking air.

Another clarification is that the hose is a hard nylon and its OD is 5/16" so its not going to fit over the bottle neck.

[Mike C]

Bottle caps - at least in the UK - are not rigid, so getting a good seal would be a problem.

How about something like this, though I don't know the outlet diameter.
https://www.ikegger.co.nz/products/carb ... ng-adapter

Screen Shot 2023-05-26 at 07.55.35.png (253.22 KiB) Viewed 7 times