Can you provide a bit more background on the system you're working on? Are you considering the hydropneumatic tank for transient protection? Are you conducting a steady state or EPS in WaterCAD or WaterGEMS, or a transient analysis in HAMMER?
You might find some general information in the book Advanced Water Distribution Modeling and Management
In HAMMER, there are many factors to consider when sizing a hydropneumatic tank for surge protection, some of which are listed in this article:
Modeling Reference - Hydropneumatic Tanks
Jesse DringoliTechnical Support Manager, OpenFlows ProductsBentley Communities Site AdministratorBentley Systems, Inc.
Answer Verified By: nkg2
I created a wiki for this question/answer because it applies some great step by step thinking in order to layout the solution to the problem. It can be found here for any future engineers who may have a similar question: communities.bentley.com/.../24986.how-much-do-vsp-svfd-s-help-to-reduce-the-number-or-size-of-hydropneumatic-tanks-in-a-system Mark
Answer Verified By: Sushma Choure