PADI Divemaster Certification Practice Exam

What is the partial pressure of oxygen (PO2) when using EANx30 at 30 meters?

1. 1.0

2. 1.2

3. 1.4

4. 1.6

The correct answer is: 1.2

To determine the partial pressure of oxygen (PO2) when using EANx30 (30% oxygen and 70% nitrogen) at a depth of 30 meters, understanding how to calculate PO2 is essential. The PO2 can be calculated using the formula: \[ \text{PO2} = \text{Fraction of O2} \times \text{Total Pressure} \] At a depth of 30 meters, the total pressure is influenced by both the atmospheric pressure and the pressure due to the water column above. The total pressure can be calculated with the following approximation: \[ \text{Total Pressure} = \text{Surface pressure} + \text{Water pressure} \] \[ \text{Total Pressure} = 1 \text{ atm} + (30 \text{ m} / 10 \text{ m/atm}) = 1 + 3 = 4 \text{ atm} \] The fraction of oxygen in EANx30 is 0.30 (or 30%). Thus, the PO2 at 30 meters can be calculated as follows: \[ \text{PO2} = 0.30 \times 4 \text{ atm} = 1.