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?
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:
Jesse DringoliTechnical Support Manager, OpenFlows ProductsBentley Communities Site AdministratorBentley Systems, Inc.
So I think I've kind of figured out the problem. My nodes on the check valves were reversed. The downstream node was listed as the upstream node. I've changed it and everything has gotten 'better'. The only problem that I'm having now is that the pressure I was seeing before 174 PSI at the check valve, I'm not seeing it now. I'm only seeing 159 PSI. The 174 PSI is very close to what we see in the field so that's what's throwing me off. So far, I've reversed the nodes on the check valve and have decreased the length on the suction line and increased the suction line size (to make it match field conditions) and it has changed some (from 134 PSI to 159 PSI) but not entirely. Do you suspect it's a calibration issue at this point or is there something else that could be in play? I just don't see how the pump would be showing a discharge pressure of 174 PSI and would change to 159 PSI as soon as I reversed the nodes on the check valve.
Yusuf Rashid said:I just don't see how the pump would be showing a discharge pressure of 174 PSI and would change to 159 PSI as soon as I reversed the nodes on the check valve.
Was the 174 psi seen when the check valve was closed due to the incorrect orientation? If so, that would seem to suggest that your pump was pumping against a closed check valve and would be operating at the shut off head.
Generally speaking there are a great deal of things that can impact the pressure. It could be a calibration problem (see tips here) where something in the model does not match the field conditions (like demands, element status or pipe roughness), or it could be due to a data entry problem (bad physical parameter entered, wrong orientation, wrong status, problematic controls, etc).
When looking at pressure, one thing to keep in mind is that the pressure is relative to the node elevation (the pressure of water above the reference elevation). So, it is usually better to compare hydraulic grade, in case there is uncertainty in the node elevation, or which elevation the field measurement was taken from. For example the pressure may have been read at ground elevation but the model could be assuming actual pipe elevations (though in that case you would see model pressures higher than measured pressures). See more here.
I think it was the pump going against the check valve. The number was just so like field conditions that I keep thinking it's something else but I'm pretty sure it was just pumping against the check valve. Now I just need to figure out how to calibrate the model.
A dumb question, if the calibration is off, would it make a huge difference on the hammer transient results?