What is the maximum percentage of pressure change allowed for a compressed-air foam system to pass the test?

The maximum percentage of pressure change allowed for a compressed-air foam system to pass the test is set at 10%. This standard is crucial for ensuring the reliability and effectiveness of the system during operation. A maximum pressure change of 10% signifies that the system maintains stability and performance under typical operating conditions, which is essential for effective firefighting operations.

When a system is tested, if the pressure change remains within this limit, it indicates that the system is functioning correctly without significant leaks or flaws. This ensures that in real-world scenarios, the foam produced will provide the necessary coverage and effectiveness against fires, maintaining both safety for the fire service personnel and efficiency in firefighting efforts.

A lower threshold, such as 5%, might be overly stringent and not practical for various operational conditions, while higher thresholds could indicate potential failures in the system that might compromise its effectiveness. Thus, the 10% limit strikes a balance between operational reliability and practical testing standards.