Results
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Estimated Activation Time
s
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Ceiling Jet Temp at Activation
degC
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Ceiling Jet Velocity at Activation
m/s
Note: RTI values: fast-response sprinklers 25-50 (m*s)^(1/2), standard sprinklers 80-200, rate-of-rise detectors ~30, fixed-temp detectors 100-400. Alpha values: slow=0.003, medium=0.012, fast=0.047, ultra-fast=0.188 kW/s². Per NFPA 72 Annex B and SFPE Handbook.
Reference
Alpert Ceiling Jet (SFPE Handbook Ch. 14):
For r/H > 0.18: T_cj = T_amb + 5.38*(Q/r)^(2/3)/H
u_cj = 0.195*Q^(1/3)*H^(1/2)/r^(5/6)
For r/H <= 0.18: T_cj = T_amb + 16.9*Q^(2/3)/H^(5/3)
u_cj = 0.96*(Q/H)^(1/3)
RTI Model: dTd/dt = sqrt(u)/RTI * (T_cj - T_d)
Typical RTI: fast-response sprinkler 25-50, standard 80-200