I have placed a FCV before pumpins station for flow control. I created a valve setting pattern same as the node on the downstream side to analyse it in EPS. but it is showing following errors:
1. FCV cannot deliver flow.
2. Maximum trials exceeded.System may be unstable.
3. Negative pressure at FCV.
4. Negative pressure at downstream junction.
5. Negative pressure at downstream pump
How can i fix these issues?
You can fix this by not using a flow control valve. While they my sound nice to a modeler, they are almost never installed in real systems and they are very expensive. There is almost always a better solution. What exactly are you trying to accomplish with the FCV?
Placing an FCV in front of a pump will cause NPSH problems which is what this model is telling you.
This Wiki article was created by Dr. Walski to support his comments in this post.
HTH,
Larry
I want to limit the water flow that can be pumped on the downstream side of a tapping point. I have a transmission main which is supposed to supply water at two different zones( say Z1 & Z2). But tapping for Z1 is on the upstream side of Z2 and also there is a pumping station for Z1, because of which Z2 is not getting the required amount of flow. So I placed a FCV on the tapping of Z1 on the upstream side of pumping station to limit the flow.
Did you get the negative pressures in the model before placement of FCV? Is the flow setting causing the negative flows i.e. check if downstream demands are satisfied.
Did you follow the troubleshooting steps mentioned in wiki provided by my colleague Yashodhan?
Problems when using a flow control valve (FCV) downstream of a pump
If required, you may upload model files for our review.
Sharing model files.
Regards,
Sushma Choure
Bentley Technical Suppport
If yo are putting a pump at the start of Z1,what most people would do is put a variable speed pump at the start fo Z1. This would give you better control and save energy as compared with an FCV which has a fixed setting and wastes energy.