Where should oxygen readings be taken in the tank to confirm successful inertion?

Taking oxygen readings at the bottom, middle, and top of the tank, including at the ends and the middle, provides a comprehensive assessment of the oxygen levels within the tank during inertion. This approach ensures that the entire volume of the tank is evaluated, accounting for any potential layering of gases that may occur due to differences in temperature or density.

By measuring at these different heights, it’s possible to identify whether inert gases have successfully displaced oxygen throughout the tank’s entirety. This thorough method enhances the likelihood of detecting any residual oxygen pockets that could pose a risk during subsequent activities such as maintenance or removal.

Focusing solely on middle or providing a single reading would not reveal potential variations in oxygen content, which is critical in confirming that inertion has been effectively achieved. Additionally, it's impractical to take readings every 5 feet without correlating those measurements to specific points of interest like the ends and the middle, which are more relevant for assessing the inertion process effectively.