pressure not changing

0882.White Oak Waterline Extension.wtg

Hello Billy, 

Thank you for uploading the .wtg file, but along with .wtg file we also need the .wtg.sqlite file to open the model, can you please upload it ?

Generally changing the initial level of tank should change the hydraulics and pressure should drop by some amount, but in your case you might have some other boundary elements like valves in that pressure zone or model which is controlling the HGL and pressures in the model. 

Thanks for your reply, I do have a couple valves in the system. I \had to zip the file to get it under the upload size.White Oak Waterline Extension.wtg.sqlite.01.zip

Hello Billy, 

Thank you for uploading required files,

You are modeling a steady state, where tank's HGL is fixed and it will be equal to initial elevation of tank since there is no source to fill the tank e.g. reservoir.  The tanks will drain if you don't have a reservoir or negative demand as a source in EPS simulation. 

The reason why pressure at J-3 doesn't reduce is because HGL at tank is equal to initial elevation 3225.01 ft and it cannot go below this value because base elevation is 3225 m, so this way you cannot reduce pressure at J-3 as HGL at tank cannot be lower than current value. If HGL at tank increases pressure at J-3 will increase since it is a gravity system as HGL increases pressure increases. 

You would need to put PRV here to reduce the pressure, else there needs to other hydraulic boundary like valves, pumps, reservoir to change the HGL in the network. 

Hope this helps.