I am working on a WaterCAD model and am simulating a hydrant with a pump and reservoir. The problem I am having is that the fire flow test result for that location shows both the static and residual pressure is the same at 100psi, and the flow is 1,430gpm. How do I represent this with the pump? The 3-point curve created from this data causes an error.
OpenFlows | Water Infrastructure Forum - WaterCAD Hydrant Simulation
Hello Jonathan,
You would typically use a pressure when the flow is zero and the pressure when the hydrant is flowing. You would then choose some flow and calculate the what the pressure would be using the following equation: Qr = Qf * (Hr/Hf)^.54. I would recommend reviewing the following link in order to set up the pump curve: Modeling a connection to an existing system.
Regards,
Scott
Are you trying to model a hydrant, or a connection to an existing system? If you are using a hydrant test to develop a pump curve to simulate the connection to an existing system to model a downstream expansion (such as a subdivision), then you would need to have some difference in pressure between the static and residual tests. The purpose of the pump approach to modeling a connection is to simulate the change in pressure as the flow into the new system changes.
If the pressure is 100 psi both when the hydrant is closed and when it is open, that may be an indication that the outflow is greatly restricted by the hydrant opening size and that the water main has far greater capacity. In this case, you could simply model it as a reservoir with elevation set based on the HGL corresponding to that 100 psi. In other words, you might be able to assume a constant 100 psi at the connection point. You could also considering taking the hydrant pressure measurements at different times such as peak hour, and you could set up different scenarios with a different reservoir elevation corresponding to the pressure at the connection point for those conditions.