Which foam system involves mixing foam concentrate with water and air on site?

The foam system that involves mixing foam concentrate with water and air on site is known as batch mixing. This method allows firefighters to create foam by combining the concentrate with water in a specified ratio directly at the site of use. The batch mixing process ensures that firefighters can adapt the mixture based on the specific needs of the situation or the type of fire they are combating.

Batch mixing is advantageous because it offers flexibility and control over the foam's concentration, which can be crucial when dealing with different fire scenarios. This on-site preparation enables resources to be utilized effectively, particularly in emergency situations where rapid response is necessary.

Other foam systems, such as balanced pressure, inline educators, and portable proportioners, have distinct mechanisms and applications. Balanced pressure systems typically create foam by maintaining equal pressure for water and foam concentrate, while inline educators mix the concentrate with water using the pressure of the water supply. Portable proportioners provide an easy means of mixing foam concentrate directly with water but often rely on predetermined ratios and may not involve the same level of site-specific adaptation that batch mixing does.