Upgrading Scuba Gear - DIN or Yoke on Regulator?

[MLOI]

Originally Posted by sveinung

Sounds like you're describing 200 (5 threads) and 300 (7 threads) bar tank fittings, they're two different lengths/depths
Both 300 and 200 tanks will fill on a 200 bar compressor.

Not quite. The male 200 Bar DIN fitting on the compressor will not be deep enough to seal in the 300 Bar female on the tank - so you can't fill 300 bar tanks with 200 bar fittings.

But in reality it's not a problem - most fill stations will have 300 bar male fittings on their bank / compressor, which can be used to fill 200 or 300 bar tanks. For a while the 300 bar fittings had a protrusion in the middle to stop them sealing in 200 bar tanks -but 5 minutes in a lathe gets rid of that. (only some 300 Bar DIN fittings had this anyway)

So, make sure that all your regs are 300 bar DIN - that's the 7 thread version as stated. Then you can use them on 200 or 300 bar tanks.
Rather than a screw on adapter, see if you can get a conversion kit to convert your reg to yoke if you ever need to. Using the adapter on a single tank pushed the reg forward so it becomes an interference fit with the back of your head. Swapping over is the equivalent of removing and replacing a bolt - trivial.
(I have mainly apeks regs, and it was cheaper to buy the regs in yoke and buy the piece to convert to DIN than the other way around. Might be worth checking.)

Tanks I tend towards 200 bar valves, but have a mix. 200 bar tanks can have an insert screwed into the valve to convert them to yoke valves, but 300 are too deep to do this with. It's worth carrying one of the inserts with you if you are taking tanks - lets you get fills from a yoke only compressor setup easily.

I don't believe that there is any meaningful strength difference between 200 and 300 bar fittings - both are well overspecced. It was only done in an effort to ensure 200 bar fittings were not used on 300 bar tanks. Then everyone realised that 300 Bar tanks are not worth the effort, so normal use is to run 200 bar gear at 220 ish bar - which hasn't caused any problems.

On tanks - don't even bother trying to bring tanks into AU. The US DOT stamp is not accepted here, and the numbnuts in Australian Standards insists on annual hydro's here. Tanks cost ~ $100 for an ali 80 or $200 ish for the better faber 12l steels second hand. So not a massive expense. Rest of south pac is a lottery, depends on the shop as to what they will accept. I've had tanks in test in AU filled in Vanuatu.

Mike