EPANET Minor Loss Coefficient for reducers/expanders

[withak36301]

Am presently trying to set up a model in EPANET for a water supply system to some cyclone cleaner banks. Dilution water is pumped from a tank to several cyclone cleaner systems. I have two questions:
1) How do I determine a minor loss coefficient for a reducer (or expansion) in a pipe? The User manual does not provide any formulas for these....
2) How best to model the cleaner inlets, which have a pressure requirement? Right now, I have them modeled as reservoirs, which have a head. Is this the best way?
Please advise.

 

[fel3]

For #1: Any first-semester fluid mechanics text should cover this subject (at least Daugherty & Franzini did). Or, look at Crane Technical Paper 410, Hydraulic Institute Engineering Data Book, Handbook of Hydraulics (King, et al), etc. Or, do an Internet search for minor loss coefficient reducers. Lots of hits.
For #2: I think your method is good. Take the elevation of the inlet and add the pressure head to get the effective reservoir elevation. If the pressure head varies with flow rate, you may need to come up with a different approach. However, since I haven't had to deal with this type of situation, I don't know the best way to handle it.

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"Is it the only lesson of history that mankind is unteachable?"
--Winston S. Churchill

 

[1503-44]

I dont use EPANET, however most hydraulic analysis software does have a flow element that you can set to give a loss proportional to the flow going through it. If they do not have a special name for that element, call the reducer a valve and simply set the appropriate Cv. It must be able to do that. Reducer losses depend on which way they are installed and the D1 to D2 ratio. See Crane. I probably can lay my hands on a table, if you don't find it somewhere first. Oh look. There's some appearing now.