HAMMER, Hydropneumatic tank

Question

Is it possible that in the HAMMER, the Hydropneumatic tank element can give more flow to the system than the volumen wich is set to have? It happens to me that if I create the Flow graph in the Transient I see that it gives more flow than the one it was set to have

Jesse Dringoli · Answer

Hello Andres, 
 Mass balance should be maintained during a transient simulation in HAMMER, unless the tank becomes empty (or an air or vapor pocket forms and air enters the system). 
 Are you seeing any user notification about the tank becoming empty? 
 What version of HAMMER are you using? 
 When you look at the flow graph, are you also considering possible inflow into the tank at the same time? 
 Also note that the initial volume of liquid may be computed by the program, so you'll need to confirm it based on the difference between the full tank volume, and the gas volume reported at the first transient timestep. This can be seen in the "Extended node data" tab of the Transient Results Viewer, if you enter a number in the "report period" field. See more about that in the Reporting section of this article: Modeling Reference - Hydropneumatic Tanks 
 If this does not help, please provide further details to illustrate what you are seeing, and if needed, a copy of the model files with steps to reproduce: Sharing Hydraulic Model Files on the OpenFlows Forum