On cold days, preheating the propane tanks is recommended because which statement is true?

• A. The temperature of the liquid propane controls the burner pressure during combustion
• B. Preheating has no effect on burner pressure
• C. Propane vaporizes instantly regardless of temperature
• D. Air density changes flavor of flame

Answer: (A)

The situation tests how propane supply and flame stability depend on the liquid’s temperature inside the tank. Propane in the tank exists as liquid, with some of it boiling into gas to feed the burner. The regulator sets the pressure that reaches the burner, but how much gas is available to boil off into vapor—and thus the burner pressure—depends on how quickly the liquid propane can vaporize. When you preheat the tank on cold days, you raise the liquid’s temperature, which increases the vapor pressure and speeds up vaporization. That gives more gas to the burner and helps maintain a consistent burner pressure and flame.

So, the statement that the temperature of the liquid propane controls the burner pressure during combustion is the true one. Preheating affects how much gas is produced and available to the burner; the other options don’t accurately describe the relationship between temperature and burner performance.