Final answer:
The most accurate statement about foam concentrates is that the application rates vary for different types of polar solvents as these rates depend on the specific properties of the solvent. While not typically found on the container, this information should be followed as per the manufacturer's guidelines or industry standards.
Step-by-step explanation:
The most accurate statement about foam concentrates is that foam application rates are different for each type of polar solvent. Foam blankets can be very beneficial on unignited fuels as they prevent vapor release and can provide a cooling effect. The application rates for foam can indeed change depending on the properties of the polar solvent involved in the fire, such as its reactivity and solubility. The rate of application would not typically be marked on the container but instead, would be detailed in guidelines provided by the foam manufacturer or industry standards.
It's important to note that foaming agents can reduce the surface tension of water. Surfactants, including fluorinated surfactants, are added to create these foaming agents which enable the fire-extinguishing foam to spread across and blanket the fire effectively. This is especially useful for fires involving organic liquids, which are often large scale.
As for the application method, it can vary; however, applying foam in short bursts and observing its effect is more of a tactical consideration than a factual statement about foam concentrates themselves. Therefore, option B is indeed the most accurate choice.