EPANET 2 questions

[Ristanovic]

Hello to everyone,
If i connect pipe to the tank... where is really that connection point? Is that top of the tank, bottom...?
That is critical point if I want to simulate inflow or outflow from the tank!
Thanks,
Marko Ristanovic, Civil Engineer

 

[RWF7437]

If you are working on a real system you should be able to find out how and where the inlet and outlet pipes are connected. Go look at it.

Almost certainly the inlet/outlet will be at the bottom of the tank. It makes little to no sense to draw water from only the top of a tank.

good luck

 

[Ristanovic]

RWF7437, it is real system and because inlet pipe is on 1m below top of the tank and outlet pipe is on 1m above bottom of the tank.
It is so complicated system... when pumps are working, they are pumping water through 2 main pipe lines. One is going directly to the tank and second is going directly to the network. Tank is filling from both sides, from inlet pipe and outlet pipe because pressures are high from both sides. When pumps are off, water goes back to the network from both sides (inlet and outlet) until water level in the tank is below inlet pipe (1m below top of the tank) and after that water goes only through outlet pipe. In reality it is like that and I need to simulate that scenario. So I would like to know this figures about level (position) of connection point on the tank in the model. How is EPANET doing that? Is pipe connected like you said at the bottom of the tank and if it is like that, can I "cheat" somehow?
Thanks RWF7437

 

[RWF7437]

Your word description us unclear to me ( this is not unusual). Can you post a diagram of the system showing the pipes, pump(s), elevations, sizes and lengths ? Especially, show the overflow elevation of the tank. Your description doesn't mention this essential information. Are you even sure that the higher pipe IS an outlet or is it an overflow ?

 

[Ristanovic]

RWF7437, I have found the answer on my question... I'll not post a diagram, I don't need it for now...
Thank you!

 

[hydrae]

I see how it can be done:
connect both pipes to the tank.
ignore the bottom 1 meter, so the model tank is 1 m above the real tank, this simulates the effuent pipe at 1 m above the bottom of the tank
On the infuent pipe, use a statement in 'controls' to turn the pipe to closed when the tank is below the level of 1 meter of the tank top, this prevents the pipe from being used when it cannot.
Hydrae

 

[Ristanovic]

Hydrae thanks a lot... truth is that sometimes Epanet is a little bet "stupid" but it is free
Also this with 'controls' is sometimes problematic and it is really question if it will respond on each 'rule'...

 

[hydrae]

Yes I have found the rules do not always engage, the work around is to decrease the interval and ignore the single point errors. that will get your answers, then tweaking the rule order or the accuracy can fix the single point errors.
Hydrae

 

[Ristanovic]

Can somebody tell me if I am wrong...
In Epanet you have Base demand, Demand multiplier and Demand Pattern. What is what? Can I treat Base demand as Daily average consumption (Qd,av), Base Demand x Demand Multiplier as Daily maximum (Qd,max) and Base Demand x Demand Pattern as hourly maximum (Qh,max)?
=Right or wrong?

 

[hydrae]

Ristanovic

Patterns are intended to be used for time based changes such as hourly or even minute by minute
Demand multipliers are intended to be used for growth calculations

But how you used them is up to you

I also use patterns to also calculate a fire flow
such as a 2 hour fire of xxx gpm at node x at 7 am

Hydrae