SCUBA Tank (Cylinders) FAQ

As of Summer 2022, the Metal Impact brand name is being 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. During the transition you may find references to either name on our website.

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 and oxygen compatible 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 oxygen clean and oxygen compatible 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 or more oxygen compatible.

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 'rejection 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.

Hot-dip galvanized (HDG) tanks develop a streaked and mottled appearance although over time that becomes more uniform. Do NOT attempt to remove the white, grey, or black looking discoloration, it is normal and part of the protection provided by the zinc metal coating.

Hot-dip galvanizing (HDG) on Faber brand steel tanks offers the best possible durability and corrosion protection. However, the cosmetic appearance of the thick hot-dipped galvanized finish is NOT as perfect and consistent as a painted finish over hot-spray galvanizing. We feel cosmetics is unimportant in relation to durability and only offer HDG finish when available for steel tanks.

If the tank 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.