The Aluminum 80 cu ft (11.1 liters) cylinder is the staple of the diving industry. You most likely used them in your first Scuba Class and on most charter boats around the world. The tank is a 3000 psi (200 bars) service pressure tank measuring 25.8″ (65.5 cm) tall with a 7.3″ (18.5 cm) diameter. The cylinder weighs 31.5 (14.3 kg) is negative 1.7 lbs. (771 g) when full in salt water and is positively buoyant 4.2 lbs. (1.9 kg) when empty.