What must be done to the water discharge pressure when using an eductor?

• A. It must be lowered to prevent back pressure
• B. It must be increased until foam flows
• C. It must remain constant throughout the application
• D. It needs to be adjusted based on the hose length

Answer: (B)

When using an eductor, the water discharge pressure must be increased until foam flows. This is because an eductor operates by creating a vacuum that draws in foam concentrate into the water stream as it flows through the device. For the eductor to function effectively and create the desired mixture of water and foam, a specific minimum pressure is required.

By increasing the discharge pressure, you ensure that the water flows through the eductor at a sufficient velocity, enabling it to generate the necessary suction to pull the foam concentrate into the water. If the pressure is too low, the eductor might not work effectively, leading to insufficient foam generation or even a complete lack of foam output.

Maintaining the proper pressure is crucial for achieving the desired firefighting capabilities, particularly in situations where foam is needed for effective suppression, such as flammable liquid fires. This highlights the relationship between water discharge pressure and the successful operation of the eductor in foam application.