In hydraulic systems, which type of pressure is significant for calculating the flow available from hydrants?

Residual pressure is essential for determining the flow available from hydrants in hydraulic systems. This pressure reflects the amount of pressure that remains in the system when water is being drawn from the hydrant. When a hydrant is opened, it allows for water to flow; however, this flow creates a drop in pressure due to the demand placed on the water supply. The residual pressure provides insight into the system's ability to deliver water effectively after accounting for any loss in pressure caused by flow.

Static pressure, while relevant, measures the pressure in the system when there is no flow occurring. It does not account for the conditions when water is actively being used. Dynamic pressure refers to the pressure of the fluid in motion, which is not used to assess the conditions at hydrants. Pumping pressure is generally related to the pressure provided by a pump and does not reflect the pressure available at the hydrants under flow conditions.

Thus, residual pressure serves as the most accurate measure of the flow capability from hydrants, making it the correct answer for this question.