Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Is QUANTITY='spot obscuration' still effective at FDS 5.4.1 version? #858

Closed
gforney opened this issue Jun 24, 2015 · 5 comments
Closed

Is QUANTITY='spot obscuration' still effective at FDS 5.4.1 version? #858

gforney opened this issue Jun 24, 2015 · 5 comments

Comments

@gforney
Copy link
Contributor

@gforney gforney commented Jun 24, 2015

Application Version:FDS 5.4.1
SVN Revision Number:4697
Compile Date:Sep. 28, 2009
Operating System:window XP

Describe details of the issue below:

I simulated Examples/controls/device_test.fds at FDS and the result 
(device_test.output) shows the smoke detector activation time. I am sure 
the result came from the command, &PROP QUANTITY='spot obscuration'.

Where can I see the user guide for "spot oscruation" at FDS use guide or 
technical report or something else for technical expertise? At FDS user 
guide, I can only find the rules for ionization or photoelectric detector 
with the user input for alpha(e,c), beta(e,c), or Heskestad ionization 
detector with L, or ADS, or beam detector specification by user input. 

As I understand, the activation time for smoke detector is one of the most 
important engineering findings and one of the most sensitive subjects for 
engineers to deal with performance-based fire risk evaluation for 
commercial smoke detectors as well.

Comments would be greatly appreciated.

Original issue reported on code.google.com by jmhak1 on 2009-09-30 12:40:15


- _Attachment: [device_test.out](https://storage.googleapis.com/google-code-attachments/fds-smv/issue-884/comment-0/device_test.out)_ - _Attachment: [device_test.fds](https://storage.googleapis.com/google-code-attachments/fds-smv/issue-884/comment-0/device_test.fds)_
@gforney

This comment has been minimized.

Copy link
Contributor Author

@gforney gforney commented Jun 24, 2015

We changed some of the names of output quantities to make them more 
consistent. 'spot obscuration' is now 'CHAMBER OBSCURATION'. We use the 
term 'CHAMBER' to indicate the inside of a smoke detector. There is also an output

called 'PATH OBSCURATION' that is appropriate for a beam detector.

Does this answer your question?

Original issue reported on code.google.com by mcgratta on 2009-09-30 12:49:04

@gforney

This comment has been minimized.

Copy link
Contributor Author

@gforney gforney commented Jun 24, 2015


Thank you, I understand.
One more thing please.
I checked the difference bewteen Heskestad model and Cleary Ionization model
I ran several cases and the result for activation time of detector is quite similar

to each other (nearly less than 1 % of difference).
Then, what is major difference between Heskestad and Cleary model or method?

That is to say,
1. For Heskestad;
 &PROP ID='..", QUANTITY='CHAMBER OBSCURATION', LENGTH=1.8, 
ACTIVATION_OBSCURATION=3.28/
2. For Cleary; 
 &PROP ID='..", QUANTITY='CHAMBER OBSCURATION', ALPHA_E=1.8, BETA_E=-1.1, 
ALPHA_C=1.0, BETA_C=-0.8, ACTIVATION_OBSCURATION=3.28/

Original issue reported on code.google.com by jmhak1 on 2009-10-04 10:05:30

@gforney

This comment has been minimized.

Copy link
Contributor Author

@gforney gforney commented Jun 24, 2015

There is a discussion of smoke detector models in the FDS Technical Reference Guide,

Volume 1.

Original issue reported on code.google.com by mcgratta on 2009-10-05 11:51:54

@gforney

This comment has been minimized.

Copy link
Contributor Author

@gforney gforney commented Jun 24, 2015

There is a NIST GCR report 07-911 that describes the sensitivity of the different
variables in the smoke detector model.  If the velocity is sufficiently high, there
should be little difference between the Cleary and Heskestad models.

Original issue reported on code.google.com by Stephen.Olenick on 2009-10-05 13:15:00

@gforney

This comment has been minimized.

Copy link
Contributor Author

@gforney gforney commented Jun 24, 2015

(No text was entered with this change)

Original issue reported on code.google.com by mcgratta on 2009-11-23 21:41:55

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Projects
None yet
1 participant
You can’t perform that action at this time.