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Author Topic: Pyrosim - detector activation  (Read 8685 times)

MichaelC

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Pyrosim - detector activation
« on: March 22, 2015, 02:56:53 pm »

Hi all, can anyone tell me how to find out at what time the detector or sprinkler activated?
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Dave McGill

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Re: Pyrosim - detector activation
« Reply #1 on: March 22, 2015, 05:36:49 pm »

Hi Michael,

Here are 3 ways.
  • look at the detector in Smokeview; a heat detector will change colour in it's center, and the link in a sprinlkler will dissapear upon activation.
  • Check the _devc.cvs file. You can see the detector temperature climb, and determine when it reaches it's activation temperature.
  • If the simulation runs to completion, then at the end of the .out file, it will list the activation times of the detectors.

Dave
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MichaelC

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Re: Pyrosim - detector activation
« Reply #2 on: March 29, 2015, 07:40:16 pm »

Hi Dave
Thank you for your reply, very helpful.
My next issue it that although the sprinkler heads seem to be activating they do not seem to be affecting and controlling the fire. Any ideas?
Michael
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Dave McGill

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Re: Pyrosim - detector activation
« Reply #3 on: March 30, 2015, 08:30:37 am »

Hi Michael,

There are two possibilities.

1. You have selected sprinkler links instead of sprinklers. The former just places a link that will indicate if the sprinkler reaches its activation temperature. It does not discharge any water.

2. You have to specify the extinguishing coefficient for the surfaces in your model Search for E_COEFFICIENT  in the FDS Users Guide. This is an unvalidated feature, and you will be forcing the fires to diminish, rather than modelling it based upon the material/surface properties.

Dave
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Dave McGill
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MichaelC

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Re: Pyrosim - detector activation
« Reply #4 on: March 31, 2015, 01:41:39 pm »

Hi Dave
Thank you for your reply but they are sprinklers rather than links. Any ideas?
Kind Regards
Michael
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Dave McGill

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Re: Pyrosim - detector activation
« Reply #5 on: March 31, 2015, 03:44:28 pm »

have you configured them to discharge an appropriate amount of water?

It would help if you attached your file.
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Dave McGill
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MichaelC

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Re: Pyrosim - detector activation
« Reply #6 on: March 31, 2015, 04:31:50 pm »

Hi Dave
Thank you for your assistance, the file is attached.
Kind Regards
Michael
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Dave McGill

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Re: Pyrosim - detector activation
« Reply #7 on: April 02, 2015, 07:52:13 am »

Hi Michael,

The sprinklers were essentially embedded in the ceiling slab. I lowered them all by 0.2 m. The trick is to preview the model in Smokeview and look at the proximity of the sprinklers to adjacent surfaces. Rotate the model in Smokeview and ensure that you can see the entire sprinkler, and that there is a visible gap between the sprinkler and the adjacent surface.

Here are a couple of other suggestions.
  • Change the alpha value of the colour of your glazing to `0.3. That way, it will still look like glass, but you will be able to see the smoke filling the room without having to clip the geometry.
  • I assume you have a quad-core. If you split the apartment mesh in two, the simulation will probably run close to twice as fast.

Dave
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Dave McGill
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MichaelC

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Re: Pyrosim - detector activation
« Reply #8 on: April 05, 2015, 03:22:50 pm »

Hi Dave
Thank you for your assistance, I will lower the sprinklers to see the effect. In my recent version I have also changed the sprinklers from 1.0L/min to 115L/min in line with our code. Would this be the correct approach?
I'm not sure if you noticed, but none of the detectors now operate, I shall look at the model to ensure that they are below ceiling height now.
Kind Regards
Michael
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MichaelC

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Re: Pyrosim - detector activation
« Reply #9 on: April 06, 2015, 04:53:04 pm »

Hi David
Thank you for your recent assistance but I am still having a number of issues even after your suggested changes.
The sprinklers are now activating but not suppressing the fire. You will notice I only located sprinkler heads in the fire area, should I be locating them throughout the apartment?
In addition, bar the stair detector, none of my other detectors are now activating.
I have attached the updated file and would appreciate any assistance you may be able to give me.
Kind Regards
Michael
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Dave McGill

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Re: Pyrosim - detector activation
« Reply #10 on: April 06, 2015, 06:02:28 pm »

Hi Michael,

Read the section on E_COEFFICIENT in the FDS Users Guide.

At the moment, the value of E_COEFFICIENT for your burner is 0, so there is no chance on the sprinkler suppressing the burner. Even with a high value, it won't suppress it completely.

Read this thread. http://www.thunderheadeng.net/forum/index.php/topic,2605.0.html

The other detectors may not be activating due to the cooling effect of the initial sprinkler. Look in the _devc.csv file and check to see what is happening to their temperatures.

Dave

Dave
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Dave McGill
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MichaelC

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Re: Pyrosim - detector activation
« Reply #11 on: April 06, 2015, 06:19:25 pm »

Hi David
Thank you for this advice. I have set the model to run again and adjusted the HRR to stop growing via the ramp function.
I shall look at the outputs again when it finishes running but the heat detector should have activated before the sprinklers did.
Kind Regards
Michael
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Dave McGill

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Re: Pyrosim - detector activation
« Reply #12 on: April 06, 2015, 06:24:35 pm »

try lowering the heat detectors.
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Dave McGill
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MichaelC

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Re: Pyrosim - detector activation
« Reply #13 on: April 06, 2015, 06:27:21 pm »

minds thinking alike here, after your suggestion about lowering the sprinkler heads, I also did this for the detectors before this current run. Will let you know the outcome.
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MichaelC

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Re: Pyrosim - detector activation
« Reply #14 on: April 08, 2015, 03:20:35 pm »

Hi David
Where is the hrr_freeze feature located within Pyrosim?
Kind Regards
Michael
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