During the annual maintenance, which type of extinguisher requires an internal examination?

The correct response is that the cartridge-operated dry chemical extinguisher requires an internal examination during annual maintenance. This type of extinguisher utilizes a cartridge that releases gas, which propels the extinguishing agent. Over time, the internal components might be susceptible to corrosion or damage, making it critical to perform a thorough internal inspection to ensure the extinguisher functions properly when needed.

Annual maintenance is vital for all extinguisher types, but the need for an internal examination specifically arises from the design and mechanism of cartridge-operated extinguishers. This examination involves checking for signs of wear, integrity, and potential issues that could impair performance.

While stored pressure dry chemical extinguishers and carbon dioxide extinguishers do require annual inspections, they do not necessitate the same level of internal examination as cartridge-operated designs. Stored pressure dry chemical extinguishers typically only require external checks and pressure verification, while carbon dioxide extinguishers focus on verifying pressure and checking the horn for blockages. Thus, the cartridge-operated dry chemical extinguisher stands out for its need for comprehensive internal scrutiny during maintenance.