This isn't funny anymore.
It appears that certain UK based nitrous system retailers are selling the wrong pipe fittings.
(You know who it's likely to be, and if you don't then it doesn't matter, please don't let this important subject descend into poking fun at them, besides they may not be the only ones)
Now the vast majority (all?) of nitrous systems use fittings and pipes in a standard AN type tapered fitting, this fitting type is widely available in the USA being as it was specified for their Airforce / Navy (hence AN)
While AN fittings are widely available in the USA, they're an utter bitch to get in the UK, only generally available through nitrous dealers importing the stuff then adding a vastly proffitable mark up for themselves.
So of course any UK based company trying to save a few pence a time is going to try and find an alternative, so off they trot to their local hydraulics shop.
Mr. friendly hydraulics man takes one look and says it's a JIC fitting, JIC being a commonly available standard of fitting, well he doesn't know nitrous is still 20 years out of date does he ?
(American industry uses a LOT of JIC fittings by the way)
So "cheap ass UK nitrous co" opts for the cheap ass plated steel JIC fittings, but to maintain appearances will often use AN type hoses with their cute red and blue ends and you end up with this;
Thats right, AN fittings (the brass one) are 37 degree taper and JIC fittings (the silver one) are 45 degree taper.
Great ! So you end up with a tiny ring of taper doing all the sealing, not so bad until its been tightened a couple of times, by which time its dug into the softer brass and made a pit and won't seal no matter how hard you swing on the spanners.
Since its the pipe that got destroyed (usually) the only cure is to replace the hose with a JIC standard hose, or change it for an AN hose and change the fittings too.
The BIG clue this is going on is if the joint feels spongy when you do it up, matching tapers practically go solid the moment the tapers meet and if you can manage to get more than a flat of the hex turn on the nut you're doing well.
People who should know what they're doing should realise this, but don't.
The instant give away will be gold / yellow steel fittings and the gold will turn silver where you used a spanner.
Long term, steel corrodes like you wouldn't believe with nitrous, fittings should be brass / alloy / stainless. NOT mild STEEL.
Here's an example of what to avoid;
So you thought you could cheat the system when you found it cheaper did you ?
Cheaper doesn't mean better value, cheaper often comes at a price, QUALITY.
How else did you lose out ?
Well performance for a start, just look at the step created by the mis-match. Lovely eh ?