Question 932 Deck General

The correct answer is B) one meter from the deck. Before a tank is crude oil washed, the oxygen content in the tank must be measured at a position one meter from the deck, as per the relevant regulations. This is because the area one meter from the deck is considered the most representative location to measure the oxygen level, as it is away from potential pockets of low oxygen near the top of the tank, but still close enough to the main body of the tank contents. The other options are incorrect because: A) the vent riser may not be representative of the tank atmosphere; C) the top of the tank may have lower oxygen levels due to stratification; and D) immediately above the oil level may not be the most representative position.