The large Nitrox tank wrap requirement mostly depends on your local dive shop fill policy.
When Nitrox was introduced to sport diving there was widespread anxiety at local dive shop fill stations about cylinder contamination and handling safety. There were also fears of an injury as the result of an unqualified diver inadvertently breathing Voodoo Gas. While there is no law that requires the Nitrox wrap, the highly visible Nitrox tank wrap was helpful in addressing those early concerns. Today, experience has demonstrated those safety worries about Nitrox to be relatively minor issues for the sport diving community. However, the large tank wraps themselves have now become an issue because they can promote rapid corrosion of the cylinder wall.
The large Nitrox tank wrap has proven to be an imperfect solution to ensuring handling safety and identifying cylinder contents. Many fill stations have adopted policies and practices that do not rely upon the presence of the Nitrox wrap. As a result, some local dive shops have become ambivalent about requiring the large wraps and are satisfied with a small removable tape label or tag that indicates cylinder contents analysis. The factor that often determines the large permanent wrap requirement at many local dive shops is how the shop handles Nitrox fills. Shops that fill using premixed gas tend not to require the large wraps, but shops that partial pressure blend in the cylinder itself may still require the wraps.
In the early days practically all Nitrox fills were done using partial pressure blending, causing a common misconception that presence of a Nitrox tank wrap indicates the cylinder and valve are oxygen clean and oxygen compatible. However, the Nitrox wrap does NOT indicate the oxygen cleanliness or oxygen compatibility of the cylinder and valve, the wrap is just a label of the cylinder contents. A separate evidence of inspection decal (aka VIP sticker) is what indicates if cylinder and valve are both suitable for use with compressed gases containing more than 23.5% oxygen at the date of inspection. Conversely, the EOI decal does NOT indicate what compressed gas is stored in the cylinder and is no substitute for cylinder contents labeling.
