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12-13 m/s in ESFR branches. How to reduce velocity?

Question asked by raminta on Aug 21, 2018
Latest reply on Aug 21, 2018 by nocivus

Hi,

I would like to get your brainstorm advice. I have project which shall follow sprinkler design standard EN 12845 (not NFPA this time).

ESFR ceiling sprinkler system (room area 1745 m², room H=12 m): pendant K-360 [25.2] sprinklers, minimal pressure at sprinkler 2,7 bar. The number of sprinklers assumed to be operating 12 units (9 m²/spr.), t = 74 °C.  

Please see below sprinkler plan:

From control valves room to sprinklers feedmain there is DN200 feedmain (L=~50 m). Coupling pipelines system is designed. Branches are connected straight to the feedmains (without standpipes). 

I have existing pumps, so I calculate balanced system to evaluate maximum demands (I could not install PRV, because pump capacity matches system need). Due to I have high velocity in DN50 branches.

According to national regulation EN12845 "Pipes greater than DN50 shall not be supported from corrugated steel sheet". Steel sheets are at designed building. So, I could not design bigger than DN50 branches. According to building constructions there is no place to hang additional DN150 feedmain. What would you think could help to resize velocity in branches (13 m/s) to max 10 m/s? Is this 13 m/s velocity makes much damage to the pipelines (big vibrations?) or this is small velocity increase that should not be evaluated and system will still operates well?

 

Thank you in advance!

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