If a contaminant (fuel) is present and the oxygen inside a cylinder is under sufficient pressure, impact from a fall or blow can indeed be the ignition source for an oxygen-fed fire. Although ignition of this type occurs very rarely, it’s still a good idea to handle a pressurized cylinder with care at all times. Always follow all applicable DOT guidelines when transporting cylinders. Secure cylinders when transporting them so that they will not roll around, rattle about or strike other cargo or hard surfaces. Protect cylinders from falling and impact by using chain restraints, padding, straps and dollies during transportation and use. Also, always exercise great caution when hand-carrying all pressurized scuba cylinders, especially those containing oxygen or oxygen-enriched mixtures.