Extended Time Period Analysis for a Tank Using EPAnet

Maybe you could add an elevated second tank to accept flow and then meter flow to primary tank...

https://www.pcswmm.com/Downloads/USEPANET

I built a tank for greywater with a high and low float switches using an arduino for control. The low switch turned the pump off when the level got too low but would not turn back on until the level came back up and went all the way to trigger the high level switch. When the pump started up again, it would pump up to a holding tank system that slowly drained into the garden. Like Eagle said, you may need two tanks, one dynamic and one passive.

I had one extra switch to add for overflow but decided a passive overflow to a drain made more sense as it would work even if the power went out and/or the pump failed.

Thank you for the suggestions, but maybe I didn't explained well the problem (as you may have understood I'm not fluent in english ). Allow me to try with this sketch:

I have to evaluate how the tank's volume changes (due to the demand pattern) mantaining constant the Hydraulic Grade Line (i.e. constant flow between the reservoir and the tank), because the pipe is attached higher than the maximum level. As far as I understand EPANET builds the HGL always connecting the two water surfaces, is there a way to tell EPANET that the pipe delivers water higher than the tank's water surface instead of the bottom level?

Thanks again for your help, best regards.

It should be in here ↓ ....these programs take time to learn, there are a ton of tutorial sites available...

http://unix.eng.ua.edu/~rpitt/Class/Water%20Resources%20Engineering/M4c%20EPANET2%20example%20Class%20Version.pdf

I re-read this thread, and without knowing your software specifically, I can suggest that you may need to add in some sensors to the lower tank in order to have level data available to the program. If all you can tell the program is that the two tanks are connected, then it can only simulate a simple connection. I makes sense that the connection is at the bottom as this will be self leveling. If the program doesn't know about the elevation differences then it doesn't need to know about the pipe placement beyond the bottom connection.

You probably need to complete the model and fill in all the sensors and elevations in order to unlock some of the programs capabilities.

Why do you need to simulate this system? What pumps and valves and level sensors do you have?

I have followed some tutorials to build the model but unfortunately none of them mentioned this particular detail, neither the one you suggested does.

I found a better image of the situation that I'm modelling: do you know if EPANET can represent this particular configuration?

Tanks again.

Thanks for your effort Deefburger

I have been given the task to verify a urban tank storage capacity, which means to analyze the behaviour of a storage tank's volume with the predicted city populaton at year 2048. Since it is the first time that I face such a problem, I decided to try the free software EPANET to evaluate how the tank's volume changes in time (due to a given demand pattern). I followed some tutorials to build the simple model with just one pipe connecting a reservoir and a tank like the system on the image above, with no pumps, nor valves. I need to mantain constant, throughout the 24 hrs simulation period, the Hydraulic Grade Line so that there is a constant flow between the reservoir and the tank.

To be brief, I need to perform the extended period simulation with a constant inflow to the tank but so far I couldn't find how to do it so I ask if someone who uses EPANET knows if it is even possible to do it.

In order for the lower tank water level to remain constant, the net in-flow to the lower tank must equal the net out-flow from the lower tank (not shown)...

As the net water level in the upper tank will yield a declining head at the upper tank outlet, and therefore, other factors remaining unchanged, the upper-tank out-flow will not remain constant...

For ''balance'', ( system In-flow - system losses ) = ( system out-flow )

Try to quantify the maximum and minumum demand quantities for a 24-hour period on the lower-tank outlet, in order to estimate the highest and lowest storage capacities needed in the upper-tank to supply those demands...

The lower tank water level can't be constant, my purpouse is to predict how it will change during the 2048 day of maximum consumption. Also the upper tank is in fact a reservoir, so its water level remains unchanged: this is a property of the element "reservoir" in EPANET (and it is acceptable because it works as a lake), so its head won't decline making possible to ensure the constant flow in the water supply. The lower tank out-flow follows a given demand pattern and my purpouse is to verify if the tank's current dimensions will be adequate in 2048 or if it will be needed a bigger tank to store the volume that compensates the difference between the constant in-flow and the variable out-flow.

It seems the lower tank should be enclosed with an air bleed valve on the top...this way the tank will always be full....You only have to calculate the feed line size to accommodate max demand...

How much water is supplied to how many consumers by the water supply system now?...

How how much water is expected to adequately serve how many consumers via the water supply system in 2048?...

Don't have those estimates? Then, find someone who does...