🔍 Key Concepts

• Thermal expansion of liquids – what usually happens to most liquids when they are heated • Relationship between temperature, density, and volume for a fixed mass of fuel oil • How fuel tanks are loaded to allow for expansion space (ullage) in hotter conditions

💭 Think About

• If the mass of fuel oil in the tank stays the same and its temperature increases, what must change in the density and/or volume? • Think about why engineers and deck officers must avoid filling a fuel tank completely full in cold weather if the ship is sailing to a much warmer climate. • Compare fuel oil to other common liquids like water: when you heat them up, do they occupy more space or less space?

✅ Before You Answer

• Assume the quantity (mass) of fuel oil is fixed – you are not adding or removing fuel, only changing temperature. • Recall the general rule: for most liquids, density decreases when temperature increases. What does that do to volume? • Consider why tank gauging and loading limits take temperature into account to prevent structural damage or overflow.