FAA Powerplant Written Practice Test

As air temperature increases, what happens to the allowable pressure range inside a fire extinguisher container?

1. It goes down

2. It stays the same

3. It goes up

4. It fluctuates significantly

The correct answer is: It goes up

As air temperature rises, the pressure within a fire extinguisher container also increases due to the principles governed by the ideal gas law, which states that for a given volume of gas, pressure is directly proportional to temperature when measured in absolute terms (Kelvin). As the temperature increases, the kinetic energy of the molecules within the extinguisher increases, resulting in a higher pressure within the container. Fire extinguishers are typically designed to operate within specific pressure ranges, which are calibrated for safety and effectiveness. If the temperature increases significantly, it can cause the internal pressure to rise beyond the allowable range, which could lead to potential failure of the extinguisher. Consequently, the design takes into account temperature variations; therefore, the allowable pressure range increases to accommodate the higher pressures that result from higher temperatures. This ensures that the extinguisher remains safe and effective under varying temperature conditions. It is essential for users to be aware of this relationship between temperature and pressure, especially in environments where fire extinguishers may be exposed to extreme heat, as failure to consider this could result in malfunctions or hazards.