Get over yourself.
Did I quote you? No. So why assume this my reply was directly aimed at you.
Generally it was aimed at the suggestion that this was a scam, that a much cheaper solution was available, and that the idea was a head could be fitted by just buying one off the internet. No one specific.
I explained that having been in exactly the same position that cylinder that's failed cannot be returned because the regs are designed to stop transportation of cylinders deemed unsafe, which was what I was lead to believe and have accepted.
If you didn't ask the question about why you can't have the cylinder only then the logical question would be to ask the test centre the question. If you didn't get the answer you wanted then you could get a second opinion from another centre or possibly Idest.
Transporting an empty bottle not
in test is the issue. Your bottle is
not in test. It has failed.
I am lead to believe the regs are
The Carriage of Dangerous Goods (Classification, Packaging and Labelling) and Use of Transportable Pressure Receptacles Regulations 1996.
Info on the go-no-go here :
https://www.scubadivermag.com/propos...inder-testing/
I am also lead to believe that a cylinder without a head will not be stamped as passed as the head could be retro fitted afterwards which has failed.
So hopefully that answers your doubt on that point, but if not, phone a test centre/Idest.
Of course you can't fill a bottle without a valve. That's why the test includes the valve. Not sure what point you're trying to make.
The law on cars and cylinders are not exactly the same. I was trying to demonstrate how the test works as an analogy not saying every rule applies to both in the same way. Sorry if you didn't follow that.
So to answer your questions directly to you:
How a valve that had had such little and very light use could fail and how could I avoid damage in the future?
It can happen, and you could use grease to protect the threads and make sure that if you fill a cylinder you use an adaptor which takes the pressure stress when you unscrew, not the DIN.
Was it right / fair that a test centre can keep / destroy the equipment if one doesn't authorise / pay for parts and labour?
As I am lead to believe by 2 centres, yes, and have stated what one said when the same thing happened said. But you can check with another or Idest. Idest are going to be the no.1 source of info, if you doubt one test centre why take another's word?
Yes. I waste a lot of time on the internet. The 1000's of posts I have here is just one forum, I run another where I have plenty more, and also run a few other shooting related websites. What I know from that experience is that unless someone is willing to put their name and professional qualification out on the line then a huge amount of what is said is said without citing a source, and (as in my own example) it's often heresay. The best place to find out about the actual facts is to contact the official parties directly, which you could have done by now, instead of wasting time on the internet arguing about it and getting nowhere. You could have actually found out I wasn't right, the test centre wasn't right and had what you want returned and a new head fitted by another shop. Or you could have got all angsty about it and posted again.
The reason why I post about this is because over the years I have seen people take shortcuts with HPA all to save time, effort and small amounts of cash... sticking cylinders in vices to get adaptors in and out, getting hold of cylinders that would fail a 2 year visual and putting new heads on them filling and painting them so they look new and have plenty of life for the 5 year then selling them. I've also seen people weld handles to cylinders, weld gauge adapters to cylinders, and tap their own quick fills into cylinders, or fit HPA to co2 (the latter sending a valve through someone's leg). And there are plenty on social media selling out of test gear.
So I'd suggest as it's Saturday, phone the other place up and have a chat. Then you can come back and post something useful like you expect others to instead of just having a hissy fit because you don't like what someone on the internet has posted.