** WARNING THESE ARE USUALLY SHIPPED UNDER A "SMALL" AMOUNT OF PRESSURE.
Trust me, there is enough pressure in there to knock you on your ass when you are taking the stab valve appart. Empty the pressure furst by pushing down on the little red valve cap on top.
THIS PAGE IS STILL UNDER CONSTRUCTION
In the Beer industry you can buy these single use Beer Kegs made from PET (Pop bottle plastic). They are very strong and have great handles around the top for easy carry. However, you need to strip the valve on top (called a stab valve) down until its nothing more then a handy dandy beonet lock. Probably un-necissary. but I wanted to use it.
The Keg I will be working on was sold at a Surplus Store near my home. They were clean and unused in my case. I brought them home and figured I would use them to add an external tank in my 3D Printer room for my humidifier. I found tons of information about taking apart a stab lock from an aluminum keg online, but nothing about doing it on a single use Keg like these. This article is primarily about that.
I want to say, these are listed as single use, and I have no idea why that would be the case. I ran accross a reddit thread where someone who works with these posted how dangerous these are to refill but he could not explain why it was so dangerous. I am very familiar with working with pressure vessles, I am aware of the material sciences of the materials being used here. But I can not find any reason why you would only use these one time if you are tooled to use them multiple times.
I suspect this is another person who was told over and over again, "Don't let people reuse these" with no further investigation and the person clearly had no aptitude to learn more on the topic. The person identified the stab valve as the failure point, but as you will see, even that was well built.
These Kegs are made by a company calld Pioneer Packaging (from Seattle, Portland). They have a standard pressure rating of 3.5bar, that's about 50psi. The Stab valve has two springs inside holding the plastic closed. Two small red caps on the end of the nozzel that are part of the over pressure valve that will go off at 5.2 bar (about 75psi). The stab valve is held in place by a split ring collar that goes around the valve to attach it to the PET bottle. (**WARNING: DRAIN THE GAS!!!) If you split the two halves at the seam and if you are careful they should come apart without a lot of force. Though, that should be the last time they are ever put under pressure. Then just pull it out.
Explain the printing process
The above drawings files can be found on OnShapes website