A carbon dioxide fire extinguisher is required to be recharged if the weight loss exceeds what percentage of the weight of the charge?

• A. 5%
• B. 10%
• C. 15%
• D. 20%

Answer: (B)

CO2 extinguishers are kept ready by watching how much of the charge remains in the cylinder. Because CO2 is a compressed gas, a loss in weight means a loss of usable extinguishing content, which can reduce how far or how effectively you can discharge it. The guideline is to recharge when the weight loss exceeds 10% of the net charge weight printed on the extinguisher.

So, if the extinguisher’s charge weighs 10 pounds, recharge is needed once the net weight drops below 9 pounds. This 10% threshold balances maintaining reliability with avoiding unnecessary service.

Choosing a smaller threshold would trigger recharge too often, while a larger threshold could leave you with insufficient CO2 for a proper discharge.