Ok this is a touchy subject, some guys just get on with it as if it's second nature, others step up to the rig trembling.
I'm quite experienced with high pressure air, but i still tread carefully the first time i fill at a site I've not been to, or even the first fill of the day on a site i know.
High Pressure Air, whether it's 3000psi, 3500psi, or the more favourite 4500psi, can kill you, if you are not using it correctly.
Another untouched side of this is, sites have insurance just in case any daft idiot runs into a tree or tries to eat a bunker. Are we insured to fill our bottles, should we even be allowed to fill our own bottles at a site.
Now here's the question :
a. Should we fill our bottles personally without any technical knowledge or training, as we have been.
or
b. Should the site provide a fully trained person to fill our bottles, who has had training and is insured to do this.