How to include unknown booster fans in an industrial extraction duct network?

[anisbedad99]

Hi,

I’m working on an industrial fume extraction system, with a main duct line and several secondary branches connected through booster fans.

I’ve already calculated the pressure losses for the main extraction duct, and the main fan is known (with its performance curve).
However, I have no technical data for the booster fans — no flow rate, no pressure curve, only an estimate of their motor power (e.g., 110 kW).

I’d appreciate help on these questions:

• How can I model the boosters’ effect without full specifications?
• Can I estimate their pressure rise or flow rate from motor power alone?
• How do I determine whether they assist or oppose extraction flow at the junction?
• Any simplified method, assumption, or reference to handle this?

Unfortunately, I can’t share the system schematic for confidentiality reasons.

Thanks in advance for any suggestions.

 

[LittleInch]

See my probably unhelpful response below.

• How can I model the boosters’ effect without full specifications? - You can't with any level of confidence
• Can I estimate their pressure rise or flow rate from motor power alone? - No choose one as an assumed number be it flow or PD and then you can estimate the second.
• How do I determine whether they assist or oppose extraction flow at the junction? - You can't
• Any simplified method, assumption, or reference to handle this? - Finger in the air?

 

[Rputvin]

Talking realistically of how to get this done;

1. Talk to the fan manufacturer and have them test for and deliver the needed data
2. Perform the testing yourself, or through a contracted third party testing lab that can determine the necessary data
3. (the hard work path) Find a competitor's fan with data of the same physical size - same motor and diameter - run the calcs to that known performance data, then run it at a reasonable estimated window of performance that the unknown fan is likely to run within, say +/- 10%, and state very clearly what the design window is and when it won't work
4. (the path too often taken) Make a lot of design assumptions and make it someone else's problem when it doesn't work