Scuba SAC rates (surface air consumption) are key to understanding and determining when your body needs more oxygen. This measurement of air intake is directly impacted by the type of breathing technique you use. As a general guide, adults not active should consume less than 18 liters per minute, adults in light activity will consume 18-21 liters per minute and those engaged in moderate activity will consume 21-32 liters per minute. Good Scuba SAC rates help keep you safe while diving and also extend your bottom time.