What must be done to stored pressure fire extinguishers when subjected to temperatures at or above their rating?

When stored pressure fire extinguishers are subjected to temperatures at or above their rating, the best course of action is to empty them and perform applicable maintenance. The reason for this is that high temperatures can affect the integrity and reliability of the extinguisher. Elevated temperatures can cause the pressure within the extinguisher to rise beyond safe levels, potentially leading to a malfunction or even an explosion.

Emptying the extinguisher ensures that it is no longer under high pressure, allowing for a thorough inspection and necessary maintenance to be performed. This maintenance may include checking for any signs of wear, corrosion, or other damage that could compromise the extinguisher's performance in an emergency. Once maintenance is complete, the extinguisher can then be recharged and put back into service.

While other choices may involve some level of service or check-ups, they do not directly address the necessity of managing the effects of high temperatures on the extinguisher’s performance. This makes the choice of emptying and conducting maintenance the most suitable and safe response in this scenario.