Final answer:
Portable extinguishers are intended to be used on small fires in the incipient or growth phase.
Step-by-step explanation:
Portable extinguishers are intended to be used on small fires in the incipient or growth phase. In the incipient phase, the fire is just starting and can be easily extinguished with a portable extinguisher. In the growth phase, the fire is spreading and becoming more intense, but is still small enough to be controlled by a portable extinguisher.