Sample file in instruction guides CONTAM
quang nguyen
Dols, William Stuart (Fed)
As indicated by the message, every zone/junction must be connected to ambient by a variable flow link (path/duct segment).
Paths/duct segments that utilize fan or forced flow elements are not variable flow links, i.e., their flows are specified and not allowed to vary according to the numerical solution techniques.
See Theoretical Background – Airflow Analysis – Fans section of the documentation for more information.
The bottom line is that you likely have too many fans in the system or they are located in such a way as to prevent the formation of a valid/unique solution to the set of pressure/airflow equations.
In your diagram, you should have two fans – one in the supply and one in the return branch just left of the tees.
Similar to this duct layout which has controls applied to the fans.
- Stuart
From: con...@list.nist.gov <con...@list.nist.gov>
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Subject: [contam] Sample file in instruction guides CONTAM
Hi Mr Stuart,
I have problem, when i do the example with alarm as picture:
could you share the file in instruction for Study.
Many Thank you, Stuart.
Kindly regards,
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quang nguyen
Dols, William Stuart (Fed)
There is nothing special about the controls, they were placed there to show where the fans are.
Refer to the airflow theory section and experiment with values to determine their applicability.
Also, there is a balance coefficient that will be populated if you use the Duct Balance airflow Simulation Method.
These coefficients may not reflect “as built” values, but will be set to provide design flows, from there you can schedule fan flows and allow the system to perform accordingly.