What does "flow pressure" measure during a hydrant test?

The term "flow pressure" specifically refers to the pressure measured while water is flowing through a hydrant or any other outlet under operational conditions. This pressure reflects the effective pressure available at the hydrant when water is actively being discharged, typically under the conditions of a specific flow rate.

Flow pressure is important in fire operations because it helps to determine how much water is available to firefighters and at what pressure. It informs them on how efficiently they can deliver water to fight a fire. Measuring this pressure involves using a gauge while water is flowing, which is critical for understanding the performance of the hydrant and the overall water supply system.

The other concepts mentioned, such as the pressure before flow starts or overall system pressure, do not accurately capture what is being assessed when measuring flow pressure during a hydrant test. Knowing the flow pressure helps firefighters make informed decisions about how to effectively use hydrant resources during emergencies.