Air Consumption Rates for Scuba Diving - SAC Rates, RMV Rates, Easy Calculations

By Natalie Gibb, About.com Guide

Plug the data collected during your dives into the appropriate formula below:

• Imperial SAC Rate Formula:

[ {(PSI Start - PSI End) x 33} ÷ (Depth + 33)] ÷ Time in Minutes = SAC Rate in PSI/min

• Metric SAC Rate Formula:

[{(BAR Start - BAR End) x 10} ÷ (Depth + 10)] ÷ Time in Minutes = SAC Rate in BAR/min

Confused?

If you working in Imperial format:

• "PSI Start" is tank pressure in PSI at the beginning of the dive (method 1) or test period (method 2).
• "PSI End" is the tank pressure in PSI at the end of the dive (method 1) or the test period (method 2).

If you are working in Metric format:

• "BAR Start" is the tank pressure in bar at the beginning of the dive (method 1) or test period (method 2).
• "BAR End" is the tank pressure at the end of the dive (method 1) or the test period (method 2)

For both Metric and Imperial formulas:

• "time in minutes" is the total time of the dive (method 1) or the test period (method 2).
• "Depth" is the average depth during the dive (method 1) or the depth maintained during the test period (method 2).