In-rack sprinkler fire size
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walther
May 18, 2011, 10:07:58 AM5/18/11
to FDS and Smokeview Discussions
Hi,
I would like to model the smoke generation and spread resulting from a
sprinklered rack storage fire in a large (13,500 m2) 9-12 m tall
building. The racks are 8.5 m high and are protected with in-rack
sprinklers. The building is a big Box retailer and I'm ok with using
data for the Standard FMRC commodity. I would like to prescribe the
fire, but can find fire growth data for rack storage with roof
sprinklers only (Mcgrattan and Hughes Associates articles
investigating interaction of vents, sprinklers). Does anyone know
where (if any) I can find suitable fire size data for in-rack
sprinkler controlled fires? The idea is to model (qualitatively) smoke
spread and mechanical exhaust requirements taking into account the
cooling of the fire gases by the water droplets. I would to assess IFC
mechanical smoke exhasut requirements.
As in-rack sprinkler requirements are based on 9 operating heads per
rack ( Europe) or 14 (US) I guess it is then reasonable to assume that
the max. controlled fire size will be the same irrespective of storage
height if in-rack sprinklers are installed.
I would like to model the smoke generation and spread resulting from a
sprinklered rack storage fire in a large (13,500 m2) 9-12 m tall
building. The racks are 8.5 m high and are protected with in-rack
sprinklers. The building is a big Box retailer and I'm ok with using
data for the Standard FMRC commodity. I would like to prescribe the
fire, but can find fire growth data for rack storage with roof
sprinklers only (Mcgrattan and Hughes Associates articles
investigating interaction of vents, sprinklers). Does anyone know
where (if any) I can find suitable fire size data for in-rack
sprinkler controlled fires? The idea is to model (qualitatively) smoke
spread and mechanical exhaust requirements taking into account the
cooling of the fire gases by the water droplets. I would to assess IFC
mechanical smoke exhasut requirements.
As in-rack sprinkler requirements are based on 9 operating heads per
rack ( Europe) or 14 (US) I guess it is then reasonable to assume that
the max. controlled fire size will be the same irrespective of storage
height if in-rack sprinklers are installed.
JWilliamson
May 18, 2011, 2:20:44 PM5/18/11
to FDS and Smokeview Discussions
FM Global performs most of the testing for rack storage that I am
aware of, so you should check their technical reports and data sheets.
Ingason, from the Swedish National Testing and Research Institute is
also a good reference.
It is going to be a challenge to define the heat release rate of a
controlled fire in rack storage. I would start by looking at the
storage above the highest in-rack sprinkler, since this portion would
be less affected by in-rack suppression. The commodity above the in-
racks is going to be similar to a rack protected by overhead
sprinklers only. That would be a reasonable starting point. Another
method may be to assume that all commodity between the in-racks is
burning.
When I was looking into this problem a few years ago, I tried to
determine the fire size that would activate all of the sprinklers
within the required design area (I only simulated overhead
sprinklers). I then forced the HRR to remain constant as a bounding
representation of controlled burning, and verified that no additional
sprinklers would activate over time. This essentially meant that I had
to run several simulations to determine a design fire.
On May 18, 10:07 am, walther <walther.groenew...@wspgroup.co.za>
wrote:
aware of, so you should check their technical reports and data sheets.
Ingason, from the Swedish National Testing and Research Institute is
also a good reference.
It is going to be a challenge to define the heat release rate of a
controlled fire in rack storage. I would start by looking at the
storage above the highest in-rack sprinkler, since this portion would
be less affected by in-rack suppression. The commodity above the in-
racks is going to be similar to a rack protected by overhead
sprinklers only. That would be a reasonable starting point. Another
method may be to assume that all commodity between the in-racks is
burning.
When I was looking into this problem a few years ago, I tried to
determine the fire size that would activate all of the sprinklers
within the required design area (I only simulated overhead
sprinklers). I then forced the HRR to remain constant as a bounding
representation of controlled burning, and verified that no additional
sprinklers would activate over time. This essentially meant that I had
to run several simulations to determine a design fire.
On May 18, 10:07 am, walther <walther.groenew...@wspgroup.co.za>
wrote:
walther
May 19, 2011, 3:30:21 AM5/19/11
to FDS and Smokeview Discussions
Thanks for the advice. I may end up doing something similar, but I'm
not sure that using the sprinkler design area would be accurate for in-
racks as I suspect that the roof design requirements for in-racks may
not be based on actual tests but may use "parallelism" or judgement to
arrive at roof design criteria. It would be helpful if one could get
the test data that were used in deriving the in-rack sprinkler
requirements. Fire damage pattern may be helpful.
I have read most of Ingason's research articles but none were for in-
rack sprinkler protection. They are useful to define the fire growth
rate for an unsprinklered fire and correspond to the measurements made
by McGratten for the plastics commodity (Ingason Group 2 if I remember
correctly). One could use Ingason's data for in-rack sprinkler
activation but that will give only the activation and fire size for
the 1st sprinkler. It won't be helpful in estimating the max. HRR. The
FM tech. reports will be most helpful but unfortunately these are not
available in the public domain!
One approach I'm considering is to estimate the limiting fire size for
roof only protection (i.e. max allowable commodity height and max.
clearance between top of commodity and roof sprinkler) by estimating
sprinkler activation time and keeping the HRR rtae constant
thereafter. One can then presumably reason that the fire size will be
smaller for protection with in-rack sprinklers as they would be QR and
have an activation temp. of 68 deg C versus the roof sprinklers with
141 deg C activation temperature. But, I think a smaller fire size
could possibly be more onerous in terms of smoke spread as the smoke
will probably be colder without a too significant reduction in volume
as the height of rise is more dominant that fire size.
On May 18, 8:20 pm, JWilliamson <williamson.justin.w...@gmail.com>
wrote:
> > height if in-rack sprinklers are installed.- Hide quoted text -
>
> - Show quoted text -
not sure that using the sprinkler design area would be accurate for in-
racks as I suspect that the roof design requirements for in-racks may
not be based on actual tests but may use "parallelism" or judgement to
arrive at roof design criteria. It would be helpful if one could get
the test data that were used in deriving the in-rack sprinkler
requirements. Fire damage pattern may be helpful.
I have read most of Ingason's research articles but none were for in-
rack sprinkler protection. They are useful to define the fire growth
rate for an unsprinklered fire and correspond to the measurements made
by McGratten for the plastics commodity (Ingason Group 2 if I remember
correctly). One could use Ingason's data for in-rack sprinkler
activation but that will give only the activation and fire size for
the 1st sprinkler. It won't be helpful in estimating the max. HRR. The
FM tech. reports will be most helpful but unfortunately these are not
available in the public domain!
One approach I'm considering is to estimate the limiting fire size for
roof only protection (i.e. max allowable commodity height and max.
clearance between top of commodity and roof sprinkler) by estimating
sprinkler activation time and keeping the HRR rtae constant
thereafter. One can then presumably reason that the fire size will be
smaller for protection with in-rack sprinklers as they would be QR and
have an activation temp. of 68 deg C versus the roof sprinklers with
141 deg C activation temperature. But, I think a smaller fire size
could possibly be more onerous in terms of smoke spread as the smoke
will probably be colder without a too significant reduction in volume
as the height of rise is more dominant that fire size.
On May 18, 8:20 pm, JWilliamson <williamson.justin.w...@gmail.com>
wrote:
>
> - Show quoted text -
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