If your real world situation is to have a pump downstream of the fire hydrant, then by all means use the correct pump curve, but to try to approximate a pump curve to match a pressure at a point and flow is to my garbled weekend brain not possible (needing 3 points to plot a curve when you have just two - static psi and residual psi).In practice, pipe networks consist not only of pipes but of miscellaneous fittings, services, The easiest way to do this, and the way recommended by the WaterCAD manual, IIRC, is to place a reservoir at the location of the fire hydrant tested and adjust the elevation of the reservoir to match the pressure in psi that was determined in the test. They provide you with a pressure in psi, and you need to convert it into something that WaterCAD can handle. However, when you're designing a subdivision and need to know the residual pressure at the nearest node to where you want to connect, the utility will do a pressure test at the nearest fire hydrant. Only in isolated places near the edge of the distribution network are booster pumps employed to provide pressure to customers.
Generally speaking, water reticulation networks are based on static pressures at water towers throughout the distribution network. Thanks RE: WaterCad - Inputting Hydrant Flows? francesca (Civil/Environmental) 26 Jan 08 20:58 I know this isn't really worded so much as a question but I am looking for someone to tell me where and why I am wrong. When I run these scenarios doesn't the program just get the available pressure at 1000gpm from the pump curve and subtract headlosses to determine the residual pressure at the hydrant? I'm not very familiar with the fire flow option but I have a similar situation and have set up scenarios for each hydrant and assigned 1000 gpm demand at each fire hydrant node.
From what I understand this is to estimate the available flow and the friction losses.Īlso isn't the purpose of the pump curve to approximate the equation: Why would it be correct to eliminate the pump and set the reservoir elevation equal to the elevation of the hydrant + the static head? Doesn't this ignore the friction losses between the source and the hydrant? It's my understanding that the hydrant flow test should be performed so that the residual hydrant is downstream (for lack of a better term) of the connection and the flowed hydrant be upstream.
Hi, I know this is somewhat of an old thread, but I have a similar question and thought it would be better to post here than to start a new thread.
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