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Flow Control Valve (FCV) cannot deliver flow

I am working on a network in WaterGEMS Connect Edition Update 2. In it, I have a FCV that fills a Tank and there are pumps on the other side of the tank that pull water from it. I am having trouble in certain scenarios where the FCV cannot deliver the flow that I have set in its control pattern to fill the tank.

For instance, in one scenario I have one of the discharge pumps on which drains the tank. I get an error at certain times saying the FCV cannot deliver flow, thus the tank empties and the level does not recycle.

In another scenario, I have two discharge pumps on under the exact conditions as the previous scenario. This time, the FCV is able to pull the required flow rate over the whole pattern and the tank level cycles.

Is there something I need to be aware of as far as interactions with pumps in the system?

Thanks,

Kyle

  • Is this an existing system or one being designed?

    You need to understand the operation of the valve you're calling an FCV. There are many valves that control flow that don't fit the behavior of a WaterGEMS FCV.  WaterGEMS 

    "FCVs  are used to limit the maximum flow rate through the valve from upstream to downstream"

    is that what your valve is doing? 

    If there isn't sufficient water from upstream, the FCV just calculates the flow that the system will deliver.

    I would start by graphing flow in and out of eh tank for different scenarios to determine what is causing the inflow not to keep up with the outflow.

    What is the purpose of this FCV. if it is to prevent to tank filling from draining the zone, a pressure sustaining valve can work better at less cost. If control is more complex a TCV may be best.

  • Hello Kyle, 

    Here are few other things to check in addition to Dr. Tom's reply. 

    What is the meaning of the notification "Valve cannot deliver flow", with regards to a Flow Control Valve (FCV)?

    Regards,

    Sushma Choure

    Bentley Technical Suppport

  • Tom -

    This is an existing system and yes the valve is supposed to be limiting the flow rate into the tank. The flow setting fluctuates throughout the day so that the tank level cycles. Our problem is the flow cuts out when we're expecting the tank to fill.

    Here's a screenshot of the pressures on the upstream side of the FCV:

    Here's a screenshot of the FCV operating flow:

    This drop in pressure on the upstream side is probably causing the issues then. It is during a time of peak demand from 12:00 to 4:00 pm. It's just strange because we know in the field that the tank is able to fill during this time and all the pumps/reservoirs upstream are operating as expected.

  • First this looks like a calibration issue. Something is going on around 14:00 that your model isn't accounting for.

    To get to the bottom of that issue, you may need to upload you model to our tech support team.

    I personally curious as to what kind of real world vale corresponds to the FCV. Is it

    1. A flow meter which sends a signal to the PLC to calculate the valve opening and a motorized control valve to set the valve position.

    2. A throttling valve who's setting is controlled by an operator.

    3. A pilot controlled local pressure sustaining valve that prevents teh pressure fro dropping too low when the tank is filling.