SCUBA Tank (Cylinders) FAQ

The bottom line is that all SCUBA tanks will have cosmetic imperfections from the factory supply chain and recently their cosmetic quality has noticeably declined. The recreational dive industry has long been accustomed to a "consumer grade" finish on SCUBA cylinders. However, recent changes in the marketplace means new SCUBA cylinders may often present with what could be charitably described as an "industrial grade" internal and/or external surface appearance that is similar to what is typical of bulk supply cylinders. The surfaces can have streaks of discoloration, spotting, scratches, abrasions, oxidation, and other irregularities as a byproduct of manufacturing, testing, handling and shipping.

Currently, all the cylinder manufacturers are adamant in maintaining the position that their SCUBA cylinders are O2 clean and fit for purpose as delivered from the factory. This puts the distributors and retailers of SCUBA cylinders between a "between a rock and a hard place" when consumers or untrained "inspectors" object to the appearance. If the distributor or retailer does any modifications (such as further cleaning, polishing, tumbling, or grinding) to the brand new cylinder warranted as O2 clean and fit for purpose from the manufacturer, then legal responsibility for the condition of the cylinder shifts to the aftermarket service provider. A cylinder with aftermarket treatments also technically can no longer be represented as new and O2 clean from the factory. Most retailers choose to follow the experts in this circumstance - the manufacturer plus the independent testing agency plus the certified cylinder visual inspector that all warrant a brand new and unused cylinder is fit for purpose.

With just minimal care, all tanks regardless of their cosmetics will deliver many years of service. We occasionally encounter consumers who seem prioritize the cosmetic appearance of their tanks over more significant considerations. Our practice regarding new cylinders the customer deems cosmetically unacceptable is we will accept returns (according to our Returns & Refunds policy) but will not make exchanges given the likelihood a replacement will be no better cosmetically than the original. Since the shipping on cylinders is not free, our advice to those consumers is they should reconsider their priorities. Otherwise, if cosmetics is important to ownership, they might prefer renting tanks rather than owning or purchasing locally where they may personally inspect before purchase.

In the Summer 2022, the Metal Impact brand name was transitioned to the Thunderbird brand of their parent corporation, Thunderbird Cylinders (which also acquired Luxfer brand aluminum SCUBA cylinder assets), but the cylinders are otherwise unchanged. The exclusive North American distributor for Thunderbird SCUBA cylinders is now XS Scuba, which also owns Sea Pearls. You may find references to any of these names on our website, but they are all referring to what are essentially the same aluminum SCUBA cylinder products that are all manufactured in the USA.

We strongly recommend purchasing our cylinders ONLY for use in North America and the Caribbean. All our cylinders have United States DOT and Canadian CTC testing and crown markings along with Imperial neck thread forms. The cylinders are NOT marked appropriately for use in Australia and New Zealand. Testing and marking specifications, neck thread forms, and over pressure relief device requirements in many other areas of the globe (especially Europe) are different than North American standards.

In the US and Canada, SCUBA Tanks must be hydrostatically tested every five years (60 months) and we always ship cylinders with the absolute most current test date available to us. Most cylinders have a factory test date less than 12 months old. Less popular sizes of cylinders may have a slightly older factory test date as these are manufactured infrequently.

No, due to weight restrictions our doubles packages ship as individual components ready-to-assemble: two cartons containing the cylinders (and boots for those packages that include boots) with modular valves (including port plugs) installed in the cylinders hand tight along with a third carton containing the manifold crossbar, bands and bolt kit, two loose Evidence of Inspection decals (aka VIP stickers.). You will need to assemble the package yourself prior to filling or if you prefer arrange for a local dive shop to assemble them for a fee. Assembling a set of doubles is easy if you follow our detailed doubles assembly instructions.

Yes, they will be assembled and ready to fill, if shipped via ground service within the continental United States. Transportation security and customs regulations require cylinders that ship via air transport to be obviously empty and easily inspected. Effectively that means the cylinder and valve cannot be assembled if shipping to an international address (including Canada) or via any expedited shipping method.

If you are arranging to have your cylinders delivered to a third-party package forwarder for subsequent handling, you may wish to request on your order that we do NOT assemble your cylinders and valves.

All cylinders and valves sold by us, that we describe as Nitrox Ready, are oxygen clean from the supplier. Based on oxygen handing best practices, Dive Gear Express does not use any form of lubricant during valve installation. That means all Nitrox Ready SCUBA tanks sold and assembled by Dive Gear Express, prior to initial use, are still oxygen clean from the supplier; we have done nothing to change that condition.

In rare cases, a shop will insist on some form of after-market "cleaning" before agreeing to fill a tank not sold by them. They have that right, but we want you to know that no such service can make a new empty cylinder and valve from Dive Gear Express any more oxygen clean.

Every tank we sell is inspected by us immediately prior to shipment and all our technicians are PSI-PCI certified to perform such inspections. If the cylinder is ordered with valve and VIP, we include our shop evidence of inspection 3" X 6" month and year dated decal (aka "VIP sticker") that clearly indicates "Nitrox Ready" in large yellow letters on a green background. However, If the cylinder is ordered with the "No Valve / No VIP" option then our evidence of inspection decal is not included even though the cylinder itself is always inspected.

Yes, but it's meaning is often misunderstood. Our low pressure steel cylinders are DOT-3AA-2400 design i.e. their fill pressure is considered to be 2400 psi by the US Department of Transportation rules. When we talk about LP cylinders having a 2640 service pressure, that is always 2400 + 10% overfill = 2400 + 240 = 2640 psi. It does NOT mean a 10% overfill on the 2640 psi service pressure.

If 3AA design cylinders can pass a elastic expansion evaluation during hydro testing then they qualify for a "+" stamped next to the hydro date. That "+" means they may receive a 10% overfill. This overfill allowance was instituted to improve material capacity during war time almost a century ago, but the rule remains in effect today. New cylinders will always pass, but although rare do fail on later tests, especially those that have been consistently overfilled. Many hydro test facilities will not stamp the "+" on subsequent tests after the first, because frankly the DOT prefers the + not be used.

If the cylinder and valve was assembled by Dive Gear Express with our Nitrox Ready evidence of inspection decal (aka "VIP sticker"), then your oxygen clean and oxygen compatible tank is ready to fill without further preparation. Although local dive shop fill policies vary, there should be no safety related reason for objecting to initially filling the empty SCUBA tank with oxygen compatible grade Air or Nitrox. However, shops often enforce training agency requirements or community practices for labeling, which may require additional specific gas contents or MOD decals be affixed to the tank.

Dive shops following best practices will not fill cylinders marked as being oxygen clean with ordinary CGA grade "E" compressed gases typical of most dive shop fill stations. In this case, the fill station operator can simply remove our Nitrox Ready decal and replace it with one they prefer. If you wish to order any of our tanks intending to use them strictly for air only, then upon request we can substitute an "Air Only" black and white version of our shop evidence of inspection decal (aka "VIP Sticker").

These are simple approximations, for more detailed explanations please read our article Metric vs Imperial SCUBA Cylinder Sizes.