Which of the following is true of mechanical foam concentrates?

Mechanical foam concentrates are specifically formulated to create a blanket over flammable liquids, which helps to suppress fires by cutting off the oxygen supply and preventing the fuel from vaporizing. One of the key characteristics of foam concentrates is that they must match the type of fuel they are being applied to in order to be effective. Different fuels require different types of foam concentrates; for example, some foams are designed for hydrocarbon fuels, while others are suitable for polar solvents. This compatibility ensures that the foam will form an effective layer on the fuel, allowing for proper extinguishment of the fire.

The other options either misrepresent the functionality of mechanical foam concentrates or overlook their specific application requirements. Therefore, understanding the importance of matching foam concentrates to the fuel is essential for effective fire suppression in aviation and other environments dealing with flammable materials.