The older technology for hydrocarbons uses what percentage of foam concentrate?

The correct choice is a percentage that aligns with the industry standards for older technology systems used for hydrocarbon fire applications. Historically, 3% foam concentrate has been the standard concentration used for combating hydrocarbon fires, specifically when dealing with Class B flammable liquids, which include various hydrocarbons such as gasoline and diesel.

This percentage is particularly significant because foam designed at this concentration is effective in creating a barrier to smother flames and prevent re-ignition. It is important to understand that while modern foam formulations may offer improvements and even lower application rates, the 3% figure represents a staple of older foam technology, which is still in use in many facilities and applications.

In contrast, alternative percentages—such as 1%, 6%, or 10%—either fall outside traditional practices or are associated with different applications or specific types of foams. For example, a lower concentration like 1% might not provide adequate coverage or effectiveness against heavier hydrocarbon fuels, while higher percentages like 6% or 10% would generally not be typical for most hydrocarbon incidents.