Option (set to true or false) of Automatic "Volume of Gas (Initial)" for Dipping Tube Hydro pneumatic Tank on basis of Gas Law Exponent 1.0 as for Bladder Tank.

Why Hammer cannot directly calculate itself the initial gas volume (IGV) on the basis of gamma exponent 1.0 as for bladder tank and start directly the transient with that "automatic" initial gas volume (IGV) ?

As a dipping tube supplier, we can at the end manage a sizing based on our modelling experience but for consultant it is very complicated, i think. And thus, limiting the potential use of this vessel type by modellers.

Of course, dipping tube is more complex vessel, at each iterative step if you change vessel size (or chamber volume, or vessel diameter) you will to re input vessel top and dipping tube bottom elevation etc.. This we can handle with a typical Excel sheet as enclosed.

But in addition to that we have to re-calculate and set in the vessel the IGV, this not only each time we change vessel dimension but also for each time for a predefined vessel the HGL level changes in steady state (steady state flow change, steady state roughness change, suction and/or discharge water level change in steady state, etc.). The IGV should change automatically (as for bladder tank) according to steady state computed with gas low exponent value of 1.0.

Moreover, currently to calculate the non "automatic" IGV we have to copy HT-1 HGL result value in true junction mode, set HT-1 to false junction mode, to past HGL value copy previously in HGL (initial - Operating Range), put a non zero value Liquid Volume Initial (Operating Range), then set HT-1 gamma exponent to 1.0 (for IGV in steady state), then compute steady state, then copy IGV calculated, set back HT-1 to true junction mode, paste value of IGV, change back gamma exponent to 1.2 (for transient application), then launch transient.

My opinion it that it is not practical for user. And this you have to do it each time the HGL level change for a given vessel dimension set.

What i would see, as to be more practical, is that IGV is calculated automatically : for example, you can put a box IGV calculated automatic set to True and if set to False you can let the option to change the IGV to customer request if any.

(If set to true IGV is calculated as for bladder tank with gas law exponent 1.0 : initial air quantity P*V = Chamber Volume * Atm P absolute (it is as for bladder tank here volume used is not vessel capacity but chamber volume capacity and precharge pressure is always fixed set to Atmospheric Absolute Pressure level) - as the "manual" way describes above does currently).

Me and Charlatte would really really like that we can improve and simplify for most of users the modelling on that way. If we can assist you in such a way let us know.