Lightweight metal cylinders

[sinidive]

I'm looking for lightweight (steel) cylinders available in Europe.

Moving tanks with bicycle and filling station does not want to touch carbon fiber tanks.... Thus the atypical requirement of a lightweight metal cylinder.

Want:
- Fits ~1500 liters or more of gas, so e.g. 6L@300bar, 7L@230bar, 8L@200bar etc...
- Using this for pool sessions and washing boats in the marina. Moving equipment with bike, terrain with hills, thus as light as possible
- Available in Europe, no carbon fiber (fill station refuses to touch those)

Currently I am using a 6L 300bar cylinder with an empty weight of 7.2kg, but that makes me very negative in the water even with zero weights... and would perhaps prefer to avoid the 300bar filling hassle.

 

[jborg]

Light weight, or less negative buoyancy? The two will not necessarily align. Your 6x300 is very light weight for a steel tank, since it's small, but quite negative -- as will all 300 bar tanks be, because they need to made of slightly thicker steel than 200/230 bar tanks. Thus they are higher density. For less negative buoyancy you may want an AL80 (11.1L alu), it's more or less neutral in the water (but quite heavy on land), or even an AL40 might be enough for marina work. Otherwise, look into lower pressure tanks, like an older 12x200... A 12x200 steel will typically weigh around 12.5 kg, while a 12x232 is around 14.5 kg.

 

[Tanks A Lot]

What would tick your boxes would be a 7.0L 232bar Faber steel cylinder. This cylinder will hold roughly 1530L of air at 20°C. For comparison your 6L 300bar cylinder holds 1605L of air at 20°C, so you would lose not all that much. This 7.0L comes in dimensions, with different buoyancy characteristics. The 171mm diameter cylinders are usually more negatively buoyant.

Faber makes the lightest steel cylinders I know of. ECS, Vitkovice, etc. are all heavier, mostly due to their thicker bases.

Water Capacity (L)	Diameter (mm)	Length (mm)	Working Pressure (Bar)	Empty Weight (Kg)	Empty Buoyancy Seawater (Kg)	Full Buoyancy Seawater (Kg)	Real Weight Seawater (Kg)	Empty Buoyancy Freshwater (Kg)	Full Buoyancy Freshwater (Kg)	Real Weight Freshwater (Kg)	Standards	Comments
7.0	140	605	232	7.6	0.61	-1.28	8.21	0.37	-1.52	7.97	BS 5045-7:2000
7.0	140	605	232	7.6	0.61	-1.28	8.21	0.37	-1.52	7.97	BS 5045-7:2000(PED)	Approved PED 2014/68/EU
7.0	140	600	232	8.2	0.09	-1.8	8.29	-0.16	-2.04	8.04	ISO 9809-1:2010 FOR N.ZEALAND
7.0	140	600	232	8.2	0.09	-1.8	8.29	-0.16	-2.04	8.04	ISO 9809-1:2010
7.0	140	605	232	8.5	-0.17	-2.06	8.33	-0.42	-2.3	8.08	EN 1964-1:1999 (PED)	Approved PED 2014/68/EU
7.0	140	605	232	8.5	-0.17	-2.06	8.33	-0.42	-2.3	8.08	EN 1964-1:1999 FOR RUSSIA
7.0	171	420	232	8.6	-0.26	-2.15	8.34	-0.5	-2.39	8.1	ISO 9809-1:2010
7.0	171	420	232	8.6	-0.26	-2.15	8.34	-0.5	-2.39	8.1	ISO 9809-1:2010 FOR KOREA
7.0	171	420	232	9.1	-0.7	-2.58	8.4	-0.94	-2.82	8.16	EN 1964-1:1999 (PED) FOR HR	Approved PED 2014/68/EU
7.0	171	420	232	9.1	-0.7	-2.58	8.4	-0.94	-2.82	8.16	EN 1964-1:1999 (PED)	Approved PED 2014/68/EU
7.0	171	420	232	9.1	-0.7	-2.58	8.4	-0.94	-2.82	8.16	EN 1964-1:1999 FOR RUSSIA

 

[sinidive]

Light weight, or less negative buoyancy?

Optimizing for light weight when carrying on bike and stairs... Having less negative buoyancy in water would be an added bonus. The 6L@300bar is non-optimal in water, but so small that it is not a huge hassle or a safety issue.

What would tick your boxes would be a 7.0L 232bar Faber steel cylinder.

That looks like a good solution! And seems like much more comfortable in water based on those numbers than the 6@300.

Tried to look into various 8L@200 variations, but seems like they are more heavy than the 7@232 Faber ones.

For larger tanks it seems Faber had some weight savings in 2023 ( New lighter design for Faber diving cylinders - Faber Italy ), I wonder if that means that there are also different new variations of the 7L Fabers around?

 

[Tanks A Lot]

What I have sent you above includes these "newer" lighter cylinders already.

That blog-post seems like marketing jargon to me. These cylinders have been around since pre 2000. What they did get was the CE certification, but these cylinders have been sold forever in the EU already. You will have no problem finding one of these, I'd rather be surprised if you do find one of the "old" ones.

 

[sinidive]

What I have sent you above includes these "newer" lighter cylinders already.

Thank you!

 

[happy-diver]

https://luxfercylinders.com/wp-content/uploads/2023/10/Luxfer_Type_2_Manual_06_08_19.pdf

 

[Edward3c]

Optimizing for light weight when carrying on bike and stairs... Having less negative buoyancy in water would be an added bonus. The 6L@300bar is non-optimal in water, but so small that it is not a huge hassle or a safety issue.

The lighter the cylinder the more lead you need to ware to be neutral. What's the difference on the mass being in a cylinder or in your weight belt/harness when on a bike?

 

[sinidive]

https://luxfercylinders.com/wp-content/uploads/2023/10/Luxfer_Type_2_Manual_06_08_19.pdf

Those would be cool, unfortunately the place I'm filling cylinders refuses composite ones (apparently there were some issues years ago...).

The lighter the cylinder the more lead you need to ware to be neutral. What's the difference on the mass being in a cylinder or in your weight belt/harness when on a bike?

Currently with zero added lead I'm negatively buoyant with the existing setup. And if needed I can stash away some lead in the marina (have a toolbox there and typically spare fins etc, so I don't have to lug everything). For pool I'm typically wearing very little neoprene, so quite sinky.

Cylinder has to travel home<->marina<->home<->fill station<->home... Everything else needs to travel less.

I'll get a 7L@232 Faber as suggested by Tanks a Lot.