What is the flame point of a liquid?

The flame point of a liquid is defined as the temperature that a liquid must reach for it to ignite and sustain combustion continuously. This means that once the liquid reaches this temperature, it will produce a sufficient amount of vapor that can mix with oxygen in the air and ignite, maintaining the fire as long as there is enough fuel, heat, and oxygen available. Understanding the flame point is critical in firefighting and safety, as it helps in identifying the hazards associated with different liquids and their abilities to ignite under various conditions.

The other answers describe different ignition or combustion characteristics. For instance, the minimum temperature required for a vapor to ignite instantly refers to the flash point, which is distinct from the flame point as it involves a much quicker ignition without the sustained combustion aspect. The temperature at which a liquid vaporizes does not provide information about its combustible properties. Lastly, the point where a liquid can no longer support combustion does not accurately define the flame point, as that relates to the cessation of combustion rather than its initiation and maintenance.