Pressure at my check valve is 174 PSI and directly downstream of it is 103 PSI. Is there a way to change the dimensions of the check valve or to somehow reduce the pressure drop across it?
Are you looking at steady state or EPS results in WaterGEMS or WaterCAD, or are you looking at transient results in HAMMER? Are these pressures seen at a specific timestep, or the max pressure? Is this the check valve node element, or from a check valve specified in the pipe properties?
Generally speaking the check valve node element does not include any headlosses except during a transient simulation when the valve is partially closed (see "headloss across check valve node" in this article). If you have the check valve set in your pipe, check the "headloss (minor)" and "headloss (friction)" in the "Results" section of the properties. If the minor losses are high, check your pipe's minor loss coefficients.
If you're observing these pressures at junctions on either side of the check valve, the difference could be due to a difference in elevation, as the pressure is measured as the difference between the hydraulic grade and the physical elevation. It is better to compare hydraulic grade to determine headloss.
You may also want to check the calculated Status field in the Results section of the properties, to see if the check valve might actually be closed (and possibly reversed to what you thought it was - check the to/from field)
If this does not help, please provide a copy of the model for review, with steps to reproduce: Sharing Hydraulic Model Files on the OpenFlows Forum
Jesse DringoliTechnical Support Manager, OpenFlows ProductsBentley Communities Site AdministratorBentley Systems, Inc.
This is what I'm seeing so far. I haven't done any transient analysis yet. So far only trying to do a steady state in Watergems.
Thanks for the clarification. The screenshots are showing that the head difference is not a headloss, but the head differential acting against each side of the closed check valve. Notice the "is closed" is set to "true" and the pipe "status (calculated)" is "closed". So using the last screenshot as an example, the HGL "start" is 322 ft and the HGL "stop" is 399. This means that the HGL downstream (stop side) is greater than the HGL on the upstream side and the check valve is closed due to the hydraulics.
Note that using a check valve on both the pipe and the node is not necessary - you would only need to model one or the other.
Thank you. I removed the check valve from the pipe. I'm still confused about how to fix this though. At the check valve node, the hydraulic grade is showing 475 ft and then the start on the pipe immediately after the check valve node is showing 322 ft? Even if the downstream "stop" side is showing 399 ft, why would it matter if my pressure is 475 ft?
If the hydraulics dictate that flow will reverse (try removing the pipe check valve and temporarily morph the check valve node into a junction) then the check valve will close and the downstream HGL will be higher than the upstream HGL because of the closure.
I am not sure if this is what you're saying as I cannot see the orientation of everything, so if you've checked the orientation and confirmed that the hydraulics are balanced (as seen in the Calculation Summary), please provide a copy of the model for review with any steps needed to reproduce: Sharing Hydraulic Model Files on the OpenFlows Forum
It shows balanced?
We still haven't received approval unfortunately to share just yet (still working on it). Is there anything else I can check? I really don't need the check valve for this. I was going to use this model in Hammer eventually and need it for that but didn't know if the model would work correctly in Hammer if it never worked correctly in Watergems in the first place.
From the screenshots provided so far this appears to be working as expected; the check valve closes to prevent reverse flow, isolating the hydraulic grade on each side. If you need further analysis and cannot provide a copy of the model, please provide these screenshots: