I have posted this question on seve

[Blufire]

I have posted this question on several forums on web, but I did not got an answer. I need to know if the Hazen -Williams Friction Loss Equation is mentioned in CEN standards for fire sprinkler systems (please tell me in which EN(CEN) fire suppression standard). I have found something in UNI 9489,a
standard for sprinkler systems from Italy, but I have not any copy of CEN standards on this subject.

Thank you!