Posted By Pete Stewart Hi, As a leisure pursuit, the carriage of cylinders containing compressed air for diving do not fall under current H&S legislation – do they? However, best practice would indicate that a suitable sign should be displayed to advise emergency services in the event of a bump, especially if the contain O2 rich air (EAN 32 - Nitrox). If my thoughts are correct, as above, is there a limit above which H&S regs may be applicable, i.e. I carry 2 cylinders for my use and possibly 2 others. Weight limits aside, if I were carrying 16-18 cylinders would this be classified as commercial and therefore the regs apply? Cheers, Pete