Tankerman · Cargo Calculations — Ullage vs Innage
A cargo tank is 30.0 feet deep (sounding datum to reference). The measured ullage (empty space from the top) is 6.0 feet. What is the innage (liquid depth)?
- A30.0 feet
- B36.0 feet
- C6.0 feet
- D24.0 feet✓ Correct
Explanation
Innage (liquid depth) = tank reference height − ullage = 30.0 − 6.0 = 24.0 feet. Ullage is measured down to the liquid surface; innage is measured up from the bottom. They are complementary for a given reference height.
Authority: API MPMS Ch. 3 (Tank Gauging)
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