EPANET 1

[msucvleng]

Hello, forum.

I am new to using EPANET. However, it is required for submittal on a project on which I am working. Here is a description of the situation:

I am designing a new fire water line and connecting to an existing city main. I have flow test information on a hydrant not far from my site. I need to provide the flow and pressure information at the point of connection.

Is this something that I can use EPANET to model? If so, I would welcome any information that you have.



Thank you for your time.

-Kim

 

[hydrae]

Kim

Yes EPAnet is great for that calculation.
Just follow the instructions with the program to set up your model.
The type of calculation you need should not require many of the functions.
The most complicated would be to model the back flow device if you want more than just the max flow condition.

Hydrae

 

[msucvleng]

Hydrae,

Thank you for your response. I will work on the setup tomorrow. I went thru the tutorial. Will the hydrant be modeled as a junction? If so, how do I input the information from the test flow? I'm open to any advice.

Regards,

-Kim


Thank you for your time.

-Kim

 

[hydrae]

yes the hydrant is a junction
at a junction, you can place a demand
you can have the demand fixed, or set it up as an emitter, I would go with fixed
for the source, I would setup a reservoir at the location of the of the flow test, at the static HGL
and setup a control valve just downstream to model the reduction on residual pressure during the flow test.

 

[Pinwards]

Your flow test tells you how the supplying system reacts to a demand. So in EPANET you can model the supplying system as a tank and pump. Use your flow test to create the pump curve, so that your pump represents the supplying system (rather than modeling the entire City distribution system). You can calculate the available flow at 20 psi (typically the minimum pressure in a fire flow scenario) using the flow test. This is one data point for the pump curve, the static pressure and zero flow is another data point, and the third data point is the residual pressure at the tested flow.

#

 

[msucvleng]

I am finally getting back to working on this project now that I am on spring break.

The information I have from the fire flow test is as follows:
Static 52 psi. Pitot pressure 1 = 35. Pitot Pressure 2 = 32. Residual Pressure 40. Outlet diameter 2.5
with discharge coefficient of 0.90.
The basic flow from the hydrant was 1942 GPM. Estimated flow at 20 psi. 3298 gpm, 10 psi. 3820
gpm, and 0 psi. 4287 gpm.

To model the system, I entered the following information for my pump curve:
Q (gpm)

H(ft)​

0

120.12​

1335

106.3​

1942

92.4​

In lieu of a tank, I used a reservoir at an elevation near the elevation of the fire hydrant. Because I was not present at the fire flow test, I assumed 2' above ground elevation.

I connected the reservoir to a junction with the pump in between. The pump references the pump curve and is in the open position.

I connected J1 with J2 (the connection point of my new fire waterline). I input the required information for the pipe. I assumed loss coefficient because I have no idea what is out there.

Do I need to include my proposed system in the model? What demand do I need to include at J2, if any?

So far the model ran but did not yield any flow at my point of connection.

Any help is greatly appreciated.

Thanks,
-Kim




Thank you for your time.

-Kim

 

[Pinwards]

There are no results because you have applied no demands. Now you need to look up the required Fire Flow for your structure. Most jurisdictions use Table B105.1 of the International Fire Code, you will need the Construction Type and Square Footage (both usually available from the Architect if it's new construction), look up the required fire flow in that table. If the building is fully sprinklered, most jurisdictions will allow a 50% reduction to the fire flow from the table. Now you can apply this Fire Flow demand at the node representing your fire line and run the model to see what the pressures and pipe velocities are. Most jurisdictions will want you to add the Peak Hour demand to the fire flow, and verify that the pressure stays above 20 psi (and typically velocities less than 10 fps).

#

 

[msucvleng]

My fire line t's into another proposed fireline that has a fire hydrant at each end.


Thank you for your time.

-Kim