Sprinkler cooling effect

[Dan]

I am interested to know if people actually allow for the sprinkler
cooling effect when modelling a sprinkler controlled fire scenario in
FDS.

I know that FDS doesn't allow us to limit the smoke temperature and
the only way to account for the cooling effect is to specific
sprinkler heads above the fire.

Is the predicted smoke temperature after sprinkler activates in FDS
reasonably accurate (i.e. validated)?

Do we actually need to allow for the sprinkler cooling effect in our
FDS model when modelling a sprinkler controlled fire?

[Kevin]

I do not understand completely the questions that you ask. Sprinkler
sprays that are modeled in FDS do cool the gases. The user controls
the droplet size, velocity, spray pattern, etc., but he/she does not
explicitly state that the droplets are to cool the gases.

Where is it written that "FDS doesn't allow us to limit the smoke
temperature..."?

Validation work on sprinklers can be found in NISTIR 6196-1 by
McGrattan, et al. fire.nist.gov --> BFRL Pubs Online has the document.

[Dan]

I will re phrase my question "If I am modelling a sprinkler controlled
fire scenario, do I actually need to put sprinklers in the FDS model
to allow for the srpinkler cooling effects?"

The reason why I wrote "FDS doesn't allow us to limit the smoke
temperature..." is because I was thinking along the line of using FDS
to limit the smoke temperature to 100oC, which is typically done in
zone models.

Then I guess if FDS does allow for sprinkler cooling effects then
there is no need to assume the maximum smoke temperature would be
100oC in a sprinkler controlled fire.

Thanks
Dan

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[Chris]

If you simulate a t2-Fire with sprinkler-activation time and you set
your fire constant after sprinkler activation you will see that the
smoke temp average will not be much higher as 150°C, that's the effect
of sprinklers. Nevertheless the max temp, between the sprinkler heads
and inside the fire can be much higher which can also be seen in a
simulation.
Cheers
Chris

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