Sample file in instruction guides CONTAM

[quang nguyen]

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,

[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> On Behalf Of quang nguyen
Sent: Wednesday, May 22, 2024 12:21 AM
To: CONTAM <con...@list.nist.gov>
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,

 

--
To unsubscribe from this group, send email to contam+un...@list.nist.gov
 
View this message at https://list.nist.gov/contam

[quang nguyen]

Hi Mr. Stuart,

Thanks for your quick support. Could you share your file with control link to study.

By the way, I have to build duct systemfitting, but Contam have not family as fitting, only have fill with coefficiency. We can make as picture, its right?

Thanks Stuart.

Vào lúc 20:12:11 UTC+7 ngày Thứ Tư, 22 tháng 5, 2024, Dols, William Stuart (Fed) đã viết:

[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.

[quang nguyen]

Hi Stuart.

Thank you alot for your help.

Nice day.

Kindly regards,

Vào Th 5, 23 thg 5, 2024 vào lúc 18:52 Dols, William Stuart (Fed) <willia...@nist.gov> đã viết:

[Anders Bjork]

Stuart,

This example is adjacent to my question:

Can the "performance curve" fan airflow element model be used outside of a duct system? eg, in attached .prj file, where the fan is set to blow air into one room that is pressurized, as part of the East wall?

I am trying to understand how the fan model behaves when disconnected from a control system; does the cut-off ratio and equivalent area orifice model come into play, or is the fan performance curve always "on" because there is no control signal or schedule? 

For this example, the fan cut-off ratio is 50% and the multiplier for the "userdefinedfan" airflow path is 1.0.

Thank you!

Anders

[Dols, William Stuart (Fed)]

Hi Anders,

Without a control signal/schedule the speed ratio will remain at 1.
The multiplier is not used as the control value.
You can see that the flow is into the zone in your example, whereas it should be out of the zone, i.e., driven by the AHS flow, if the fan is off.
Set the schedule or control signal to a value below the cutoff ratio on the fan to bring the equivalent orifice into play.

 

I’m attaching an example PRJ and accompanying spreadsheet demonstrating CONTAM fan curves and how multiplier comes into play.

- Stuart

 

- Stuart

 

From: con...@list.nist.gov <con...@list.nist.gov> On Behalf Of quang nguyen
Sent: Wednesday, May 22, 2024 12:21 AM
To: CONTAM <con...@list.nist.gov>
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,

 

--
To unsubscribe from this group, send email to contam+un...@list.nist.gov
 
View this message at https://list.nist.gov/contam

[Anders Bjork]

Thanks Stuart! 

That is a wonderfully simple and illustrative example and a very helpful spreadsheet. 

1. Do you know if the "Osborn problem 1" mentioned in the fan airflow path description (in the PRJ) is from the chapter on Fan Operation in Fans (1977, Osborne)? See below. Or perhaps it is another problem 1 from a different chapter? I don't need to know this desperately, I'm just curious.

from: https://archive.org/

2. I tested out the Schedule control feature and it works like you said! This will be very useful and I'm glad to understand it.

I find the "control status" panel useful: 

Thank you for the help!

Anders

[Dols, William Stuart (Fed)]

1. Yes.
   Can be verified by modifying the inputs so the multipliers and control values are all set to 1 and Tzone = 20 C.

See “DOC-AIRNET_Figs” tab of spreadsheet.
The airflow calculations of CONTAM are based on AIRNET: https://nvlpubs.nist.gov/nistpubs/Legacy/IR/nistir89-4072.pdf.

2. Glad to hear it 😊

 

 

- Stuart

 

From: con...@list.nist.gov <con...@list.nist.gov> On Behalf Of Anders Bjork
Sent: Wednesday, July 2, 2025 9:51 AM
To: Dols, William Stuart (Fed) <willia...@nist.gov>
Cc: CONTAM <con...@list.nist.gov>
Subject: Re: [EXTERNAL] Re: [contam] Sample file in instruction guides CONTAM

 

Thanks Stuart! 

That is a wonderfully simple and illustrative example and a very helpful spreadsheet. 

 

1. Do you know if the "Osborn problem 1" mentioned in the fan airflow path description (in the PRJ) is from the chapter on Fan Operation in Fans (1977, Osborne)? See below. Or perhaps it is another problem 1 from a different chapter? I don't need to know this desperately, I'm just curious.

from: https://archive.org/

 

2. I tested out the Schedule control feature and it works like you said! This will be very useful and I'm glad to understand it.

 

I find the "control status" panel useful: