🔍 Key Concepts
• Litmus paste use in cargo tank sounding for petroleum/chemical products
• Difference between ullage, innage, and thievage measurements in a tank
• Where in the tank (top, bottom, or reference point) this substance would logically be applied
💭 Think About
• Think about what property litmus (from litmus paper in chemistry) is normally used to detect and how that might relate to cargo in a tank.
• Ask yourself whether litmus paste would be more useful at the top surface, the bottom, or a reference point in the tank.
• Match each term (innage, ullage, thievage, tank datum point) with whether it refers to: amount of liquid, amount of empty space, or a reference location.
✅ Before You Answer
• Know the definitions: ullage = empty space above the liquid, innage = liquid depth from bottom, thievage = liquid sample or depth by thief, tank datum point = fixed reference mark.
• Decide at which interface litmus paste would change color or clearly mark a level (air/liquid interface, water/oil interface, or a structural mark).
• Verify which tank measurement specifically relies on detecting the actual liquid level versus a structural point.