Should I model the hydropneumatic tank on the main pipeline or should I include the short connecting pipe?
Modeling the gas vessel as being located along the main line is the preferred way to simulate this device. The influence of the short piping between the main and the vessel can be represented by means of three parameters provided with the gas vessel: Diameter of Orifice or Throat, Head Loss Coefficient, and Ratio of Losses. Essentially, the idea is to match the head loss in these short pipes with the loss incurred across a differential orifice situated in the vessel’s throat, given that the gas vessel is located along the main. Although explicitly entering the short connecting pipes to the vessel is not incorrect in principle, nevertheless it may lead to excessive adjustments in the wave speed which in turn may have an impact on the results — but, it is impossible to know for certain whether the output is markedly affected by a large wave speed adjustment.
