I have designed a water supply network with Pump of capacity 6 l/s & 70 m as head, When i check the node coming just next to pump its showing only head of 20 m. So my question is why the pump is not operating at full or max head.

Hello,

This could be related to the setup of the system. For instance, if you have a closed system with no downstream storage (like a tank), the pump will generate the flow needed to satisfy demands in the system. In such a case, the head added will be related to the flow and nothing else.

If you have downstream storage, the pump would also try to generate the head needed to balanced the hydraulic grade in the system. Pipe headlosses and downstream tank elevations will have an impact on this. This can be relatively easy to check with smaller systems. If there are a lot of downstream tanks, it may be difficult to identify causes for the issue.

If that doesn't help, we will need to see a copy of the model.

Regards,

Scott

Hello,

This could be related to the setup of the system. For instance, if you have a closed system with no downstream storage (like a tank), the pump will generate the flow needed to satisfy demands in the system. In such a case, the head added will be related to the flow and nothing else.

If you have downstream storage, the pump would also try to generate the head needed to balanced the hydraulic grade in the system. Pipe headlosses and downstream tank elevations will have an impact on this. This can be relatively easy to check with smaller systems. If there are a lot of downstream tanks, it may be difficult to identify causes for the issue.

If that doesn't help, we will need to see a copy of the model.

Regards,

Scott

Thank You very much Mr. Scott  for your reply. Actually we have 12 tanks in my network and the head losses in the pipe are abit higher, but this sizes can not be changes due to some constrain. If we check in stead state model the proposed pipe sizes are sufficient. So as you mentioned let me check with the elevation part if not then for sure i will upload my model for your further verification. 

To add to Scott's reply - here are some articles that explain how the pump operating point is based on the intersection between the pump characteristic curve and the system head curve. This may help you understand how the pumps work in your model and locate the cause of the unexpected operating point.

How are pumps handled in each OpenFlows product?

Understanding System Head Curves in WaterGEMS, WaterCAD, and SewerCAD

User notification "Pump exceeds the maximum operating point specified for the pump curve"