Hi,
In WaterCAD, after validating my network, there occurs two messages for the pump in user notifications:
1- Reference to a deleted or inactive downstream pipe.
2- Directed node has an invalid downstream link.
What do these messages mean and what can I do?
Regards,
Seylan
Hi Seylan,
Double-click on the pump then look at the properties, for Downstream Pipe. This should tell you what the downstream link is. From these two messages, it seems that the downstream pipe the pump is referencing is missing. Check your model to see if the pipe is deleted/inactive and make sure the pump is connected to an active pipe.
Nancy
Hi Nancy,
Downstream pipe is missing and I corrected it. But now, I run the system. And it gives a message in user notifications "negative pressure at pump". What can I do?
Negative pressure at a pump is exactly what it says. It's just a warning. If your pump is at elevation 850 and the tank it is pulling water from is at 840, you'll get negative pressure at a pump. It's probably an indication that you may run into cavitation problems. You need to either lower the pump or raise the suction HGL level.
Dear Bentley,
As you know The "suction element" field is no longer used in SewerGEMS V8i SELECTseries 2 (08.11.02.46, released in July), but still in Sewercad, so what if in future if Bentley would to improve pump’s properties and would to add fields for NPSH of the pump which I like to be in pumps section, will be great if we can get NPSH calculated in the model and compare it with NPSH from manufacture. Myself and as I know many engineers using Bentley products in pump stations and lift station design and that item (NPSH) good to be in the model.
Mohamad Azzam,
Hello Mohamad,
With the SELECTseries 2 release of SewerGEMS and SewerCAD V8i, the pump orientation behavior actually matches. Both SewerGEMS and SewerCAD only need the "downstream link" attribute for a pump.
Regarding NPSH - one of the great things about SELECTseries 2 is the introduction of Formula-Based User Data Extensions. With this feature, you can add your own result fields. The value in these fields will automatically update based on a formula that you enter, which can consider other calculated or user-input fields. So, in SewerCAD and SewerGEMS V8i SELECTseries 2, you can create a formula user data extension to compute the NPSH for your pumps. The next release of WaterGEMS and WaterCAD should have this feature as well.
Jesse DringoliTechnical Support Manager, OpenFlowsBentley Communities Site AdministratorBentley Systems, Inc.