Critical Path for External Static Pressure Calculations

Hello,

For ESP calculations, generally I've seen Engineers selecting the longest duct run, which has most pressure drop. It is said, this selection is enough to over come pressure drop in other ducts.

I have my doubts here. Lets consider the longest duct run has 500Pa ESP with its sound attenuators, dampers all misc accessories. Assume there is a branch duct connected to it having a pressure drop of 200Pa.
Will 500Pa ESP be enough, or should 700Pa be considered?

If its just 500Pa, I don't understand the logic of how this air can over come this additional 200Pa, when it has already burned out its energy to overcome 500Pa static??

Can I recommend the grandfather of fan/duct design.

Woods Practical Guide to Fan Engineering.


https://bit.ly/2rEnhLZ

The longest duct run is not necessarily the most resistive to airflow.
what we generally calculate is the index circuit. This is the route that the working fluid has to travel against the greatest resistance in the system.
If the fan or pump can overcome this resistance then it quite easily overcome the resistance in any lesser resistive branch ducts or pipe runs

Quote:

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Originally Posted by Brian_UK

Can I recommend the grandfather of fan/duct design.

Woods Practical Guide to Fan Engineering.


https://bit.ly/2rEnhLZ

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Thanks man!