I am trying to run the following scenario "P2 2 hr FF @WTP EPS" and "P2.4 2 hr FF @WTP EPS" in which
1. There is a 2 hr fire flow which occurs near the water treatment plant (WTP, J-600, simulated with negative demands) at J-607, downstream of PMP 600 starting at time 17:00 and running until time 19:00. The demand at J-607 at all other times is 15 gpm. From 17:00 to 19:00 a demand pattern increases the demand at J-607 to 1,500 gpm to simulate the fire flow.
2. PMP 600 pumps water directly to the tanks on top of the hill (south end o model). T-200 and T-1. Water then flows from these distribution tanks into the system at three locations (J-602, J-604 and J-12).
3. Mast meter locations (simulated with a reservoir/ FCV valve setup) also allow water into the system at various locations to help meet demands.
4. There is also a pump (PMP 1) at the top of the hill that feeds water into T-1 and T-200.
5. The WTP (J-600) fills the tank at the WTP (T-600). Water from T-600 is pumped by PMP 600 to T-1 and T-200 by PMP-600 on top of the hill via a dedicated transmission line. During a fire water at the WTP, water can flow back through the transmission line to the WTP. This line also accepts water from the system through a bypass at two of the locations discussed above (J-602, J-604 and J-12).
6. PMP-600 at the WTP is controlled by the level in the tank (T-600) at the WTP. It is set to turn off if the level in T-600 gets too low and turn on if the level in T-600 gets too high.
7. PMP-600 is also controlled by the levels in the tanks it is filling (T-200 and T-1) but the controls discussed above have a higher priority. In other words, if the tank at the WTP doesn't have enough water in in (level too low), then PMP-600 will turn off regardless of what is happening with the water levels in T-1 and T-200.
8. There is also a control on PMP-1 at the top of the hill that tells this pump to turn on when the tank levels in T-1 and T-200 are too low, or off when the tank level in T-1 or T-200 are too high.
I would like to simulate the worst-case scenario in which the pumps lose power during the peak hours (17:00 to 19:00) while there is also a fire at the WTP despite the likelihood of the situation
I want to run the fireflow simulation as an EPS to see how the system reacts to the fire, if the tanks on top of the hill (T-1 and T-200) will drain, causing undesirable pressures in Pressure Zone One, just north of these tanks or if the master meter locations can provide enough water/pressure to make up for the water leaving the tank to fight the fire at the WTP etc. There is also a bypass at two of the three locations mentioned above (J-602, J-604 and J-12) which allows water to flow from the system into the pipeline which supplies water to the WTP.
The problem is that the controls don't seem to be operating the way I think they should. The pump at the WTP (PMP-600) is not turning off at the specified time and is turning on way more frequently throughout the day when I use the clock time control. When I go into the operational controls alternative and turn the clock time control for PMP-600 off, the system acts as I would expect it to. I am not sure if I am doing something wrong or what.
I will upload the file through the secure file upload.
A quick note on how controls for PMP-600 are set before investigating further, there are 3 controls on PMP-600 and clock time control says to put the pump to off in both then and else?
Bentley Technical Suppport
I went into the model to check on that, and that is not supposed to be set up that way. The "Then" should be OFF and the "Else" should be on. However, the reason they both say OFF is when I change one to OFF, for some reason it changes the other to OFF and vice-versa. I can't set one to OFF and the other to ON.
Hi Nastassja Abercrombie,
I've also looked at your model and see that if you go to the Controls dialog and select the one in question (last one in the list), go to the Else field and pick "Find Action" (see below) and then click Select on a command that turns Pump 600 ON, (see below) you will find that it will turn ON and while the IF statement turns the pump OFF, the Else command will stay ON.
Please let us know if this still does not resolve the issue for you and we'll continue searching.
That did solve that problem yes. However, it does not seem like I can get the pump to shut off for 2 hours because the controls simply won't allow it. I decided to change the else statement to "target pressure: 115 psi", but because the tank at the WTP is draining at the time of the fire, the tank level controls override the pump shut off controls. Reversing the priority level and/or setting them equal did not solve this either. I am not sure how then to simulate a power loss at the WTP at the same time as a fire flow. Any advice?
It appears that more than one thing has changed since we received your model. So rather than us guessing about what you want to do, please send an updated version of your model for analysis. Also, please include an explanation of how Fire Flow comes into the picture. Also, please include which control it is that you want to adjust.
We will know better how to answer after we see a current model.