FAA Powerplant Written Practice Test

What factor affects the pressure limits of a fire extinguisher container?

1. Humidity levels

2. Air temperature

3. Altitude

4. Type of extinguishing agent

The correct answer is: Air temperature

The pressure limits of a fire extinguisher container are significantly influenced by air temperature. As the temperature increases, the pressure inside the extinguisher also rises due to the expansion of gases within the container. Most fire extinguishers are designed to operate effectively within a specific temperature range. When temperatures exceed this range, the pressure can increase to dangerous levels, potentially leading to a rupture of the container. On the other hand, if the temperature drops significantly, the pressure may fall too low for the extinguisher to function properly. While humidity levels, altitude, and the type of extinguishing agent can have effects on fire extinguishers, they do not directly influence the pressure limits of the container with the same immediacy as temperature. Humidity may affect the performance of some agents but does not change the fundamental pressure characteristics of the container itself. Altitude can change atmospheric pressure, but most extinguishers are designed to maintain usability across a range of altitudes. The type of extinguishing agent also varies in terms of effectiveness for different fires, but again, it does not inherently affect the pressure limits of the container. Thus, air temperature remains the primary factor affecting the pressure limits within a fire extinguisher.