What if specific gravity is <1?

• A. Vacuum
• B. Liquid expands
• C. Pressure increases
• D. Temperature decreases

Answer: (A)

When a liquid has a specific gravity less than 1, it is lighter than water. In practical terms, lighter liquids—often hydrocarbons with relatively high vapor pressures—tlee to vaporize more readily in a closed or semi-closed system. If a tank or line is being emptied or if temperature conditions change and the space above the liquid isn’t properly vented, the liquid’s vapor forms and the pressure in the headspace can drop. Without vents to supply air or allow vapor to escape, that shrinking pressure creates a vacuum, a low-pressure condition, rather than a buildup of pressure. So, with a liquid lighter than water, a vacuum is the more likely outcome in the absence of adequate venting.