Manufactures of fire sprinkler nozzles sometimes publish sprinkler K factor coefficients which describe the flow rate and pressure loss relationship through the nozzle. Usually the sprinkler k factor is determined by the relationship of flow rate through the nozzle divided by the square root of the loss through the nozzle. K = Flow / √dP


The sprinkler K value can describe the sprinkler performance in either imperial or metric flow rates (there is a metric K value and an imperial K value for the same sprinkler and these will be different values, hence it is important to check a sprinkler K value to confirm if it is a metric value or an imperial value).


The imperial sprinkler K value is calculated from US gpm (water) / √pressure loss (psi)


The metric sprinkler K value is calculated from L/min (water) / √pressure loss (bar)


When a sprinkler K (imperial or metric) radio button is selected a calculator button is enabled to allow an appropriate sprinkler K value to be obtained from a published flow rate and pressure loss.


Note: Sprinkler K factor coefficients are not the same as ‘K’ factors for standard fittings & valves.



Figure 67 Calculate Sprinkler K value




The component object can be used to model the flow rate versus pressure loss of a sprinkler component either by using a single Sprinkler K value, or by specifying a set of flow versus pressure loss curve points that defines the performance of the sprinkler.