K factor (fire protection)

In fire protection engineering, the K-factor formula is used to calculate the discharge rate from a nozzle. Spray Nozzles can be fire sprinklers or water mist nozzles, hose reel nozzles, water monitors and deluge fire system nozzles.

K-Factors calculated in Metric units;

The flow rate of a nozzle is given by q = K p , where q is the flow rate in litres per minute (LPM), p is the pressure at the nozzle in Bar and K is the K-factor is given in units of L P M / bar .

K-Factors have also been calculated and published in English units of PSI and GPM. Within the United States, only English measurements are used.

Care should be exercised not to intermix K-factors from Metric and English units as the resulting factors are not equivalent or interchangeable.