What is the discharge time requirement for a water extinguisher rated for pressure use?

The discharge time requirement for a water extinguisher rated for pressure use is typically set at 40 seconds. This time frame ensures that the extinguisher discharges its contents effectively, allowing the user adequate time to direct the stream at the fire while also ensuring proper cooling and extinguishing of flames.

Water extinguishers must provide sufficient discharge duration because they rely on displacing heat and cooling the surface of the burning material, rather than suppressing flames with chemicals. A 40-second discharge time allows for both effective application and safe operation, adhering to standards that are designed to maximize the extinguisher's performance in emergency situations. This time requirement is aligned with safety codes that establish performance criteria for portable fire extinguishers to ensure they can be relied upon during a fire event.