Scuba Diving International (SDI) Computer Nitrox Practice Exam

What should you do if you suspect the Nitrox blend is incorrect after a fill?

1. Use the gas as is

2. Test for oxygen content

3. Return the cylinder

4. Adjust the blend yourself

The correct answer is: Return the cylinder

The best course of action when you suspect an incorrect Nitrox blend after a fill is to return the cylinder. This approach is essential for safety reasons. Using the gas without confirming its composition could lead to both decompression sickness and other serious consequences during your dive, depending on your planned depth and exposure. Returning the cylinder allows a qualified technician to assess and verify the Nitrox blend. They can conduct necessary tests to determine the actual oxygen content, ensuring the gas blend meets safety standards for your diving needs. Although testing for oxygen content is a reasonable consideration, it does not guarantee that you are equipped with the appropriate equipment and knowledge to accurately adjust and analyze the gas mixture. Likewise, adjusting the blend yourself is also not advisable, as it requires expertise and specific equipment to ensure safe and correct adjustments. Using the gas as is can potentially expose you to hazardous situations, making the safest and most responsible option to return the cylinder to ensure you are diving with the correct and safe gas mixture.