What is the purpose of the pressure gauge on a fire extinguisher?

The purpose of the pressure gauge on a fire extinguisher is to indicate whether the extinguisher is full and ready for use. This gauge provides critical information regarding the internal pressure of the extinguisher, which is essential for its effective operation. A green zone on the gauge typically signifies that the extinguisher is adequately pressurized and ready for immediate use in case of a fire emergency. If the gauge indicates a low pressure (often shown in the red zone), it means that the extinguisher may not function correctly when needed, suggesting that it should be serviced or replaced.

The other options do not accurately represent the function of the pressure gauge. Measuring temperature and weight are not the purposes of the gauge, nor does it provide any information on the age of the extinguisher. Understanding the role of the pressure gauge is vital for ensuring that fire extinguishers are maintained in a state of readiness, thereby enhancing safety in environments where they are present.