The pressure in a system when no water is flowing is referred to as what?

Static pressure refers to the pressure in a system when no water is flowing through the pipes or hoses. This type of pressure is essential in understanding the behavior of water systems because it reflects the potential energy available in the system when it's not in use. Static pressure is typically measured at the pump discharge or at any point in the system when the flow is not occurring. It is an important factor when determining the adequacy of a water supply for firefighting operations since it indicates the pressure available to push water through hoses and nozzles when required.

Understanding static pressure is critical for firefighters as it ensures that they are aware of the available pressure under non-flow conditions. In contrast, flow pressure occurs when water is actively flowing, dynamic pressure reflects the effects of both flow and velocity in a system, and residual pressure refers to the pressure remaining in the system while water is flowing, which can indicate how well the system can maintain supply during operation.