UK Scuba - Cylinder Buoyancy Calculation Calculations Cylinder Buoyancy

How to calculate buoyancy of a scuba cylinder (metric)

(show me the imperial version)
Capacity: litres
Working pressure: bar
Weight: kg
Diving in:Salt water
Fresh Water

Using Archimedes principle, buoyancy is equal to the weight of the displaced water minus the weight of the cylinder.

The cylinder is made of 16 kg of steel, (which has a density of 7.8 kg/litre).
The steel therefore has a volume of 16 / 7.8 = 2.05 litres, so the total volume is 15 + 2.05 = 17.05 litres.
The density of fresh water is 1 kg/litre, giving 17.05 x 1 = 17.05 kg

Air has a density of 0.0012 kg/litre.
The air in a full cylinder weighs 0.0012 x 200 bar x 15 litres = 3.6 kg.

The cylinder when empty has a buoyancy of 17.05 kg - 16 kg = 1.05 kg
The cylinder when full has a buoyancy of 17.05 kg - 16 kg - 3.6 kg = -2.54 kg

NB - these figures exclude valves, manifolds, regulators, etc..

Common cylinder sizes available in the UK

Source of data in brackets. Mail me with any more

Beaver (steel)7.0 litre232 bar8.91kg (Stuart Webb)
Faber (steel)3.0 litre232 bar3.3 kg (web), 3.7kg (Bob Millar), 3.99kg (Richard Good), 4.7kg (Nick Ireland)
3.0 litre300 bar4.5kg (Wacker)
5.0 litre232 bar6.03kg (Keith Sabine)
7.0 litre232 bar7.5 kg, 8.0 kg (Adri Haine), 7.7kg (Tony Watt), 7.84kg (Jonathan Taylor)
7.0 litre300 bar10.0 kg (Woz)
8.0 litre300 bar12.4 kg (Kristian Lyberg)
10.0 litre232 bar10.9 kg (Chris Pitts), 11.1kg (Tony Watt)
10.0 litre300 bar14.4 kg (Iain Dick)
12.0 litre232 bar12.9 kg (Tony Littler)
12.0 litre300 bar17.0 kg (Paul Duckworth)
12.2 litre (dumpy)232 bar13.7 kg (Greg Roach)
12.2 litre232 bar13.2 kg, 13.7 kg (Chris Pitts), 13.1 kg, 13.4 kg (Greg Roach), 13.3kg (Tony Watt), 14.4kg (Bob Millar)
12.2 litre300 bar16.6 kg, 16.7 kg (Danny Burchett)
12.5 litre232 bar13.5 kg (Andy Wilson), 13.9 kg (Jonathan Fern)
15.0 litre232 bar16.0kg (Nick Ireland), 16.2kg (Richard Good), 16.3kg (Harj Jolly), 16.6 kg (Mark Trueick), 16.9kg (Tony Watt), 18.1 kg (Daniel O\'Callaghan), 18.4kg (Peter Harris)
18.0 litre232 bar22.4kg (Peter Steinhoff)
Gas Containers (steel)12.0 litre232 bar14.9 kg (Daniel O\'Callaghan)
Heiser (steel)6.0 litre232 bar110.2 kg (Marko Niemelä)
10.0 litre232 bar12.4 kg (Tony Watt)
12.0 litre232 bar14.3 kg (Mark Trueick), 14.4 kg (Rob Deenen), 15.7kg (Dick Nas), 15.8kg (Jos Havekotte), 15.9 kg (Robert Leenen)
12.0 litre228 bar14.7kg (Jim Tyrwhitt-Drake)
IKWA (steel)15.0 litre228 bar16.5 kg (Nick Ireland)
15.0 litre228 bar16.5 kg (Nick Ireland)
Luxfer (aluminium)1.0 litre200 bar1.65 kg (Dan O\'Callaghan)
1.5 litre200 bar2.08 kg (Greg Roach)
3.0 litre232 bar3.68kg (Steven Sillar), 3.8 kg (Tony Watt)
3.0 litre (2003 model)232 bar4.2 kg (Steven Siller)
7.0 litre232 bar8.8 kg (Greg Roach)
10.0 litre232 bar12.1 kg (Stefan Seitz), 12.95 kg (Sebastian Giötz)
10.4 litre232 bar13.6 kg (web)
12.0 litre232 bar16.6 kg (Stefan Seitz)
12.2 litre232 bar16.1 kg (web)
6 cu ft206 bar1.1 kg (Igor Beades)
40 cu ft206 bar6.9 kg (Igor Beades)
80 cu ft206 bar14.2 kg (Igor Beades)
ScubaPro (steel)10.0 litre232 bar12.0 kg (Adri Haine)
15.0 litre232 bar20.3 kg (Meidan Eldan)
Poseidon (steel)6.0 litre300 bar9.2 kg (Espen Brekke)
TorTec (steel), now Roth3.0 litre232 bar3.5 kg (web)
10.4 litre232 bar12.6 kg (web), 13.5 kg, 13.7 kg (Keith Sabine)
12.2 litre232 bar14.5 kg (web)
12.5 litre232 bar15.6 kg (web)
12.5 litre (dumpy)232 bar15.7kg (Zak), 16.4 kg (Dave Roberts)
15.0 litre234 bar18.6 kg (Roger Hudd, Ari Asher)
"MiniBreather" cylinders (steel)4.6 litre200 bar5.48 kg (Bob Millar)
Drager Dolphin (steel)5.0 litre200 bar6.9 kg (Billy Hammond)
Worthington (steel)3.0 litre230 bar3.75 kg (Billy Hammond)

Common cylinder sizes available in Australia

Aquanaut (steel)12.0 litre232 bar14.6kg (Alfred Zommers)
Faber (steel)3.0 litre232 bar3.8kg (David Cowan)
10.5 litre232 bar11.4kg, 11.5kg (David Cowan)
12.2 litre232 bar13.2kg (David Cowan)

Common cylinder sizes available in Belgium

Worthington (steel)12.0 litre232 bar14.4kg (David Jacobs)

Common cylinder sizes available in Germany

Aircon (steel)20.0 litre232 bar22.2kg (Josep Guarro)

Common cylinder sizes available in Italy

???? (steel)10.0 litre232 bar10.08kg (Roberto Piola)
???? (steel)12.0 litre232 bar12.08kg (Roberto Piola)
???? (steel)15.0 litre232 bar16.09kg (Roberto Piola)
???? (steel)15.0 litre232 bar19.07kg (Roberto Piola)
???? (aluminium)10.0 litre232 bar12.7kg (Roberto Piola)
???? (aluminium)12.0 litre232 bar15.7kg (Roberto Piola)
Luis Cuevas (steel)12.0 litre??? bar12.2kg, 12.3kg (Igor Beades)
Faber (steel)15.0 litre200 bar16.2kg (Ari Margolis)
Productos Tubulares (steel)15.0 litre??? bar16.5kg (Igor Beades)

Common cylinder sizes available in Russia

IDA55 Rebreather1.0 litre??? bar2.085kg (Igor Beades)

Common cylinder sizes available in Sweden

Faber (steel)18.0 litre200 bar19.6kg (Peter Steinhoff)
Luxfer (aluminium)1.5 litre232 bar2.6kg (Harald Svensson)