What is required for stored pressure type extinguishers regarding internal examination?

For stored pressure type extinguishers, the correct requirement for internal examination is that they typically do not require internal inspection at all unless there are signs of damage or the unit is being serviced. This means that under normal circumstances, they are designed to perform effectively without the need for routine internal inspection, differentiating them from some other types of extinguishers that may have stricter requirements.

Periodic maintenance, such as external inspections, is essential to ensure that the extinguisher remains in good working condition, but the internal components do not require the same level of consistent inspection. This understanding allows users to confidently maintain their extinguishers while ensuring they are compliant with safety regulations.

The other options suggest frequent inspections that are not mandated for stored pressure extinguishers under normal operational conditions, making them less applicable in this context.