Sprinkler Orifice Size Selector Calculator

Select the proper sprinkler orifice size based on K-factor, required flow, and available pressure.

Input Parameters

Results

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Required Minimum K-Factor
gpm/psi^0.5
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Recommended Orifice
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Selected K-Factor
gpm/psi^0.5
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Actual Flow at Pressure
gpm
Note: Always select an orifice that provides at least the required flow at available pressure. Residential sprinklers (NFPA 13D/13R) typically use K4.2-5.6. ESFR sprinklers require K14.0 or higher with specific pressure requirements.

Reference

K = Q / sqrt(P) Standard Orifice Sizes (NFPA 13 Table 6.2.5): 1/4" = K1.4, 5/16" = K1.9, 3/8" = K2.8 7/16" = K4.2, 1/2" = K5.6, 17/32" = K8.0 5/8" = K11.2, 3/4" = K14.0, 25/32" = K16.8, 1" = K25.2