🔍 Key Concepts

• Hygroscopic cargoes and how they interact with moisture in the surrounding air • The effect of heating a steel bulkhead on the temperature of nearby air and cargo surfaces • Relationship between temperature, vapor pressure, and dew point in a closed space

💭 Think About

• When a bulkhead is heated, what happens to the temperature of the air and the cargo that is directly against it? • How does increasing temperature near the bulkhead affect the ability of air to hold water vapor and the behavior of moisture within a hygroscopic cargo? • Which option best describes a local effect right at the heated surface, rather than a general effect on the whole compartment?

✅ Before You Answer

• Review what hygroscopic means: does this cargo absorb moisture from the air or give it off? • Think about how raising temperature usually affects vapor pressure of a substance—does it go up or down? • Consider where moisture would tend to move: from warmer to cooler surfaces, or from cooler to warmer ones?