Location to check the pressure difference in a pressurized stair (value of 50 Pa)

[Sávio Almonfrey]

 After running the simulation, where do I check the differential pressure parameter for a pressurized stair? Should it be in the door's flow path icon or by calculating the difference between the zones?  

[Sávio Almonfrey]

Could someone help me with this question?

[Dols, William Stuart (Fed)]

Please refer to the ASHRAE Handbook of Smoke Control Engineering for examples of the application of CONTAM to smoke control design.

 

- Stuart

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[Sávio Almonfrey]

  I followed the recommendation and created the model for exercise 14.3 from the book. However, the values do not match the results in the book. Could someone clarify this issue? It’s an initial understanding, but it makes a significant difference for understanding CONTAM, especially for smoke control. I have attached the file for someone who could help me.  

[Dols, William Stuart (Fed)]

I do see some items missing from your model, e.g., roof hatches, a few airflow paths, and some with incorrect multipliers.
While the pressures do seem to be in the ballpark, I cannot really vouch for the correctness of the Handbook examples.
However, I believe the example demonstrates the basic methodology to iteratively determine pressurization flows.

[Sávio Almonfrey]

  I made the corrections, but the lingering question is where and how to check the pressure difference recommended by NFPA 92. Is it by calculating the difference between the 'zone pressures' or is the pressure difference the value indicated in the door's flow path? I took a screenshot of what I'm trying to understand and clarify.  

[Michael Alcázar Fallas]

Hi Sávio.

Have you tried using the Generate Shaft Report option? You find that in the tool bar at the top, in Simulation. When you click Generate Shaft Report the software shows some instructions of what to do.

Regards,

- Michael.

[Dols, William Stuart (Fed)]

I’m not familiar with NFPA 92, but I think I understand what you’re wrestling with.

The pressure difference across the flow path, e.g., the door, takes into account the difference between the zone reference pressures and the buoyancy-related pressures associated with the zone air densities and the elevation of the opening.

So, you can obtain the pressure difference across the doorway from the following:

 

Working in SI units:

dP_door = (P_z33 [Pa] – rho_z33 [kg/m3] * 9.8055 [m/s2] * 1.067 [m]) – (P_z36 – rho_z36 * 9.8055 * 1.067)

 

If you set the elevation of the door to zero, then the pressure drop reported across the doorway will equal the difference between the reported zone pressures.

 

- Stuart

[Sávio Almonfrey]

  I did exactly what you said and got the expected results. I will continue my studies on the software and am immensely grateful.

Thank you!

Sávio Almonfrey

[Anders Bjork]

Hello Sávio and Stuart,

I am also working to generate a shaft report for the ASHRAE smoke control handbook exercise 14.3 problem.

When you use the shaft report tool in CONTAM, as discussed in this thread:

1. What should I chose as the "secondary flowpath" to get the differential pressure as needed in the example problem? and

2. It seems from the shaft report tool dialogue that I am supposed to be able to skip over Step 3). that seems useful to this situation. However, I cannot get this functionality to work. 

Attached picture is of the tool dialogue (instructions).

Thank you,

Anders

[William Dols]

Anders,

I don't have the example case handy at the moment.

However, you should be able to right-click on the first path in step 3 to generate a report for a single path.
Perhaps we need to update the documentation to be more clear.

- Stuart

[Anders Bjork]

Thank you for the quick response Stuart.

I cannot get that functionality to work, either. I am using ContamW 3.4.0.6. Do you have any other suggestions? Obviously I can work around the extra data from another flowpath, I just find it confusing.

Thank you!

Anders

[Dols, William Stuart (Fed)]

Hmm, I tested on that version as well.
Please share the PRJ and which zone/path you are working with.
Alternatively, you could use simread to generate your own, PRJ-specific results files.

 

Here is the report I obtain using the attached PRJ.

 

 

 

After selecting the Generate Shaft Report … from the Simulation menu:

1. Left-click on Zone 33 icon
2. Left-click on Path 84 icon
3. Right-click on Path 84 icon

 

- Stuart

[Anders Bjork]

Stuart,

Thanks for your help on this. I tried your method with your file, and it works great. when I do your method with my file, it also works!

When I do this:

After selecting the Generate Shaft Report … from the Simulation menu:

1. Left-click on Zone 33 icon
2. Left-click on Path 84 icon

1. Right-click on anything that is NOT path 84
   1. Zone 33 icon > tool stops
   2. Path 86 icon > tool generates shaft report with both path 84 and path 86 as if Left-click was completed

It seems like it is essential to Right-click on the same path icon in step 2. I feel confident I know how to use the tool for my own stuff now, and it works great! Let me know if you plan to update the User Guide.

Thank you,

Anders