At 150 PSI, they would be useful as expansion tanks for air compressors. Now, someone to make a manifold so we can string together a bunch of two or three liter bottles. Watch. Harbor Freight will have them next week.
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Careful!
If the plastic bottles are right off the compressor the air will be hot and that's a game changer for the plastic bottle specifications. It may work if the bottle storage was well down stream, and away from the heated air, maybe at the point of use. While It may be tempting
to reuse bottle caps for a DIY manifold, I wonder if the cap 'seals' are for tamper proofing or do they aid in securing the cap with higher pressures? I don't know but it could be exciting to find out! I think metal, or solid plastic caps are available online that would be more suitable. I use 2L bottles, pressurized to about 50 PSI to dispense lubricant to a CNC router cutter when machining aluminum. So far there's been no problem at that pressure and I reused a cap. The lube is water based and there's been no plastic reactions either.
Might be a worthwhile idea idea to put the 'air bottle' in a PVC tube just in case there is a problem. I have my 'dispenser' bottle in a PVC pipe with a glued bottom cap and a slip fit top cap to allow pressure release and changing, yet still provide fluid containment which should help any embarrassing Uh Oh's ! Good luck, and post your success. Remember that there are 'no failures'. They are just a long list of things that don't work!

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