Activation Temperature Sprinkler and Slice3D are not working.

[Beh Nou]

Hello FDS community,

I have some problems with an activation temperature of the sprinkler.

I have set it here in my test exampe to 34°C. But even directly above a big fire they dont activate. (temp is way above 300°C)

In this example there are 4 sprinklers one is activated by time and the rest is not activated at all.

Example is build like in the manual described.

And i got an problem with the 3D slices. I have them in the FDS file but how do i visualize them in SMV.

Regards,

[Kevin]

The gas temperature may be 300 C, but the sprinkler link temperature is not due to the thermal inertia as specified via the RTI. Look at the _devc.fds to see the link temperatures.

[Beh Nou]

Ok thanks for the tip. But my max temperature at the sprinklers is 20.0009°C.

I wonder how can this come since the sprinkler are directly over a hot fire.

s,C,C,C

Time,"Spr_61","Spr_62","Spr_63"

 0.0000000E+000, 2.0000000E+001, 2.0000000E+001, 2.0000000E+001

 1.2319533E+000, 2.0000000E+001, 2.0000000E+001, 2.0000000E+001

......

......

 4.5722851E+002, 2.0000018E+001, 2.0000000E+001, 2.0007367E+001

 4.5843884E+002, 2.0000000E+001, 2.0000311E+001, 2.0009292E+001

 4.5962227E+002, 2.0001280E+001, 2.0000000E+001, 2.0000579E+001

 4.6080570E+002, 2.0006025E+001, 2.0004082E+001, 2.0000088E+001

 4.6203844E+002, 2.0008505E+001, 2.0000507E+001, 2.0000000E+001

[Beh Nou]

[Kevin]

You are using 50 cm grid cells. This grid is too coarse to correctly resolve the fire and plume temperatures.

[Beh Nou]

Ok thanks for the answer. What is recommened as minimum that was a fast first test.

[Beh Nou]

With 20 cm i still get 20.002°C max... How fine do you need to mesh to get sprinkler activated.

[Kevin]

The gas temperature is only one thing to consider. The other is the sprinkler RTI. If that value is large, it will take more time to heat up the link.

[Beh Nou]

Thanks for the Answer.

Do you have a working Fire sprinkler FDS file with right Response Time Index.

Still dont understand why the air in the slice is above 300°C at the sprinkler location but only 20.0009°C in the devc file.

[Kevin]

Examples/Sprinklers_and_Sprays

[dr_jfloyd]

Put two DEVC at each sprinkler location: one that measures temperature and one that measures velocity. Do the sprinkler RTI calculation yourself and compare against the FDS result. Your sprinklers are two meters down from the ceiling in a domain with open sides. My guess is you will find that the temperatures at the sprinkler locations are not as hot as you think they are.