When conducting a water flow test, which pressure measurement is taken at the hydrant?

The pressure measurement taken at the hydrant during a water flow test is the static pressure. This is the pressure in the system when no water is flowing through the hydrant. It reflects the potential pressure available in the system and is measured before the flow begins. Static pressure serves as a baseline that can be compared to the residual and dynamic pressures observed during the flow test.

During the test, when water is flowing, dynamic pressure (the pressure during flow) will be lower than the static pressure due to the energy loss from flowing through pipes and fittings. The difference between static and residual pressures helps to determine the available flow rate and assess the overall performance of the water supply system.

Understanding static pressure is critical for professionals involved in fire protection and water supply management, as it influences the system's design and the expected performance during emergencies.