Question 62
GLI03Your ship has loaded 6,000 barrels of gasoline, at a cargo temperature of 50°F, departing New Jersey bound for Florida. API gravity is 55°. The volume correction factor (VCF) is .0006. How many barrels would you expect to unload if the cargo temperature is 90°F at the discharge port?
AI Explanation
The Correct Answer is D
### Why Option D (6,144) is Correct
The problem asks for the expected volume of the cargo (gasoline) at the discharge port, given an initial loaded volume, a change in temperature, and a volume correction factor (VCF). Liquids expand when heated, so we expect the volume to increase.
**1. Calculate the Temperature Change ($\Delta T$):**
$$\Delta T = \text{Discharge Temperature} - \text{Loading Temperature}$$
$$\Delta T = 90^\circ \text{F} - 50^\circ \text{F} = 40^\circ \text{F}$$
**2. Calculate the Total Volume Change Percentage (Expansion):**
The volume correction factor (VCF) given is $0.0006$ (which represents the change in volume per barrel per degree Fahrenheit). The total fractional change is calculated by multiplying the VCF by the temperature change.
$$\text{Total Fractional Change} = \text{VCF} \times \Delta T$$
$$\text{Total Fractional Change} = 0.0006 \times 40 = 0.024$$
*(Note: This means the volume increased by 2.4%.)*
**3. Calculate the Expected Unloaded Volume ($\text{V}_{\text{unload}}$):**
The new volume is the original volume plus the expansion.
$$\text{V}_{\text{unload}} = \text{Loaded Volume} \times (1 + \text{Total Fractional Change})$$
$$\text{V}_{\text{unload}} = 6,000 \text{ barrels} \times (1 + 0.024)$$
$$\text{V}_{\text{unload}} = 6,000 \text{ barrels} \times 1.024$$
$$\text{V}_{\text{unload}} = 6,144 \text{ barrels}$$
Thus, 6,144 barrels would be expected at the discharge port.
***
### Why Other Options Are Incorrect
**A) 5,856:**
This result would be obtained if the temperature had decreased by $40^\circ \text{F}$ (cooling, resulting in shrinkage), or if the total change calculation was subtracted: $6,000 \times (1 - 0.024) = 5,856$. Since the temperature increased from $50^\circ \text{F}$ to $90^\circ \text{F}$, the volume must increase, not decrease.
**B) 5,982:**
This result is significantly lower than the expected increase and does not correspond to a logical error in the calculation (it implies a temperature change of only $30^\circ \text{F}$ if using an incorrect negative VCF of $0.0001$). More simply, it is incorrect because it implies shrinkage, which is physically impossible when heating a liquid.
**C) 6,018:**
This result is obtained if the expansion is significantly underestimated. For instance, calculating the expansion based on only $30^\circ \text{F}$ of temperature change: $6,000 \times 0.0006 \times 30 = 108$ barrels. $6,000 + 108 = 6,108$ (still incorrect). A calculation error resulting in a much smaller expansion would lead to this answer, but it is too low based on the provided data.