30. UNDERSTANDING DETAILED ANALYSIS

[jovivier]

Do you know that IRRICAD offers Detailed Analysis in the Design options? What is Detailed Analysis and how does it differ from Analyse?

The method used in Design/Analyse assumes nominal flows when calculating pressure loss and is much like working out the hydraulics by hand. For example if you have specified a pressure of 20m at each sprinkler, Design/Analyse calculates the pressure loss in the system by assuming all the flows are the same - based on the 20m of pressure.

However, if you field-tested the pressure it would not be 20m at each outlet. Detailed Analysis calculates the resultant flow from the actual pressure at each sprinkler. In some situations, this can make a significant difference to the flows and friction losses and therefore impact on your choice of pipe sizes and pumps.

Things You Should Know About:
- Zone Design|Detailed Analysis requires the valve pressure to be set in Design|Zone Design Configuration. Initially the valve pressure from a normal analysis or pipe sizing run may be used.

- Design/Analyse can give quite conservative results and in a non-PC system it pays to run Detailed Analysis as a check before finalizing your design.

- Detailed Analysis is only useful on non-pressure compensating outlets - where the flow changes with the pressure.

- Do not use Detailed Analysis when using demand points or PC emitters (well you can use it but the flow won't change!)

- To use Detailed Analysis in the Mainline Design set the water supply pressure first. Note is it only useful for Mainline Outlets with non-PC nozzles.


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[Gennaro Vellotti]

Why not combine the two and just have Anaylsis. These days PC's run much faster, so having the more detailed anaylsis as the default wouldn't be noticed. (Will save some confusion/oversights) I know I have missed detailed many a time when running Non PC tube.

[jovivier]

Gennaro, we have thought about removing normal analysis for a number of years and may well do so in the future. However very occasionally there may be convergence issues with Detailed Analysis and in these cases the "detailed analysis factor" needs to be adjusted manually to enable a solution to be calculated. Another advantage of the Standard Analysis is that it can calculate an appropriate valve pressure which Detailed Analysis inherently cannot (it requires a valve pressure in order to run the calculations). Perhaps in the future Irricad will combine these two processes by using a standard analysis to produce a valve pressure which is then used for the detailed calculations.