What is the purpose of a pressure gauge in a fire extinguishing system?

The purpose of a pressure gauge in a fire extinguishing system is to indicate container pressure within established limits. This is crucial because the pressure within the container directly affects the performance of the extinguishing agent. A properly functioning pressure gauge allows operators to monitor whether the system is ready for use; if the pressure is too low, it may indicate that the system is not adequately charged and may not function effectively in an emergency. Conversely, if the pressure is excessively high, it could pose a safety risk. This monitoring helps ensure that the fire extinguishing system operates effectively and safely when needed.

The other choices, while related to different aspects of fire extinguishing systems, do not accurately capture the primary role of the pressure gauge. Regulating discharge speed pertains more to the design of the system rather than the function of the gauge. Measuring temperature changes is not typically a function of the pressure gauge; that role would be filled by other sensors. Predicting the propellant discharge time is also outside the gauge's capabilities, as it primarily provides a static reading of pressure rather than a dynamic response over time.