It appears to me that most regulators are designed to take 300 BAR/4400 PSI, its just the fitting from the reg to the tank that's the potentially weak link. An example of this is my CDX-5 reg which with a K valve fitting is rated at some 235 BAR (stamped on the K fitting), change the fitting to 300 BAR DIN and its now rated at 300 BAR (as per the stamping on the side of the reg and the DIN fitting). I suspect most (if not all) regulators are built to the higher rating as its no big deal for the manufacturer to do this anyway and makes manufacture easier with one pressure rating, then they put on the connector piece to suit the application thus the drop in working pressure. This also allows them to sell more primary regulators when people think they have to update their reg for a high pressure one from K valve style when changing to tech diving (and usually going to DIN fittings). All my regs are now converted to DIN so all rated at 300 BAR. If I need to use a K valve tank I simply add a converter (rated at 232 BAR) and use the tank. In this way I can use 300 BAR/4400 PSI DIN tanks, 232 BAR/3500 PSI or 200 BAR/3000 PSI K or DIN tanks.
Most of the tanks in OZ are tested to 300 BAR/4400 PSI anyway but I don't like having them at this pressure unless the WP is 300 BAR/4400 PSI
Most of the tanks in OZ are tested to 300 BAR/4400 PSI anyway but I don't like having them at this pressure unless the WP is 300 BAR/4400 PSI