Calculation of
Air Consumption
To convert depth to atmospheres:
Depth / atm’s + 1atm = ATA’s
Example: 66ft. / 33 = 2atm’s (gauge) (+) 1(air) = 3ATA’s
To calculate your Depth Consumption Rate:
PSI used / Time = Depth Consumption Rate (DCR)
Example: 225psi /3 min.= 75psi/min (DCR)
To calculate Surface Air Consumption rate:
DCR / atm’s = Surface Air Consumption rate. (SCR)
Example: 75psi / 3atm = 25psi/min (SAC)
To Calculate air use for a future dive:
Sac Rate (X) ATA’s = DCR then
Pressure available / DCR = Est. bottom time.
Example: 25psi/min (SAC) x 3ATA’s = 75psi/min. (DCR)
3000psi / 75psi = 40min. Bottom time estimated.
*There are many variables, which could and probably will effect the accuracy of this estimate.
ALWAYS CHECK YOUR PRESSURE GAUGE!
Sample Problems
Calculating Atmospheres from depth:
• What is the number of atmospheres absolute (ATA’s) if a diver is in 132ft. of water. _____________
• What number of ATA’s is 80ft.?____________
• What number ATA’s is if a diver is in 29ft.?____________
Calculating DCR
• A diver is in 66ft of water and used 1800psi in 20minutes. What is his DCR?___________
• A diver is in 132ft. of water and uses 2400psi in 12minutes. What is his DCR?___________
• A diver is in 80ft. of water & uses 1600psi of air in 15 minutes. What is her DCR?___________
Air Consumption Problems
• What is SAC rate for a diver who uses 2400psi of air at 99ft, in 20min.?_________
• What is the SAC rate for a diver who uses 1200psi in 10 minutes at 132ft.?_________
• What is the SAC rate for a diver who uses 800psi in 40psi at 33ft.?___________
To convert depth to atmospheres:
Depth / atm’s + 1atm = ATA’s
Example: 66ft. / 33 = 2atm’s (gauge) (+) 1(air) = 3ATA’s
To calculate your Depth Consumption Rate:
PSI used / Time = Depth Consumption Rate (DCR)
Example: 225psi /3 min.= 75psi/min (DCR)
To calculate Surface Air Consumption rate:
DCR / atm’s = Surface Air Consumption rate. (SCR)
Example: 75psi / 3atm = 25psi/min (SAC)
To Calculate air use for a future dive:
Sac Rate (X) ATA’s = DCR then
Pressure available / DCR = Est. bottom time.
Example: 25psi/min (SAC) x 3ATA’s = 75psi/min. (DCR)
3000psi / 75psi = 40min. Bottom time estimated.
*There are many variables, which could and probably will effect the accuracy of this estimate.
ALWAYS CHECK YOUR PRESSURE GAUGE!
Sample Problems
Calculating Atmospheres from depth:
• What is the number of atmospheres absolute (ATA’s) if a diver is in 132ft. of water. _____________
• What number of ATA’s is 80ft.?____________
• What number ATA’s is if a diver is in 29ft.?____________
Calculating DCR
• A diver is in 66ft of water and used 1800psi in 20minutes. What is his DCR?___________
• A diver is in 132ft. of water and uses 2400psi in 12minutes. What is his DCR?___________
• A diver is in 80ft. of water & uses 1600psi of air in 15 minutes. What is her DCR?___________
Air Consumption Problems
• What is SAC rate for a diver who uses 2400psi of air at 99ft, in 20min.?_________
• What is the SAC rate for a diver who uses 1200psi in 10 minutes at 132ft.?_________
• What is the SAC rate for a diver who uses 800psi in 40psi at 33ft.?___________