Measuring Scuba Cylinder Air Weight
Air has weight, so our cylinders become lighter as air is consumed. This means a diver who's neutrally buoyant with a full cylinder will become lighter and more buoyant as air is consumed. In order to ensure neutral buoyancy at the end of the dive, extra weight must be added to compensate for the loss of this weight.
To calculate the weight of air in a full cylinder, you multiply the cylinder's capacity by the density of air at sea level. For example, to determine the weight of air in a full 80 ft³ cylinder, multiply 80 ft³ by 0.08 lbs, and you see that the cylinder contains 6.4 lbs of air.
Since you'll be surfacing with air remaining in the cylinder, you'll only need to add 4 or 5 lbs of weight to ensure neutral buoyancy at the end of the dive.
To calculate the weight of air in a full cylinder, you multiply the cylinder's capacity by the density of air at sea level. For example, to determine the weight of air in a full 80 ft³ cylinder, multiply 80 ft³ by 0.08 lbs, and you see that the cylinder contains 6.4 lbs of air.
Since you'll be surfacing with air remaining in the cylinder, you'll only need to add 4 or 5 lbs of weight to ensure neutral buoyancy at the end of the dive.
