When the static pressure is 80 psi and a line flowing at 100 gpm drops the pressure to 70 psi, what is the estimated remaining gpm?

To determine the estimated remaining gallons per minute (gpm) when the static pressure drops from 80 psi to 70 psi under the flow of 100 gpm, we can look at the relationship between pressure loss and flow in a fire hose.

When water flows through a hose, there is a certain amount of friction loss due to the internal surfaces of the hose, kinks, or other restrictions. This friction creates a drop in pressure. In general, if the flow is increased, the pressure drop increases due to the additional friction losses. By understanding how much static pressure is lost, we can estimate how much flow can continue at the new pressure.

In this scenario, the drop in pressure is 10 psi (from 80 psi to 70 psi). To get an idea of how this pressure drop relates to flow, we can refer to the typical relationship established by the friction loss equations used in fire service operations. In many instances, a pressure drop of 10 psi could roughly correspond to an increase in flow back to a higher capacity, as the added demand for water would typically allow for a greater gpm output.

The choice indicating 200 gpm suggests that the flow can accommodate the drop in pressure, resulting in a relatively increased capacity