Water Flow

# Understanding the K-Factor of Your Nozzle

Authored By Chris Carson
Date December 19, 2022
Authored By Chris Carson
Date December 19, 2022
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## What is a Nozzle’s K-Factor or K-Value?

#### For example, a 150 GPM nozzle can flow anywhere between 150 GPM and 165 GPM at its rated base pressure and be compliant with the NFPA (National Fire Protection Association) 1964 standard. You can figure this out by finding 10% of your nozzle’s flow rating and adding that value to the flow rating. So, for a 150 GPM nozzle:

• 10% of 150 = 15

• 150 + 15 = 165

## Finding the K-Factor of Your Nozzle

#### Let’s work through an example with a 150 at 50 nozzle.

• K = 150/√50

• K = 150/7.07

• K = 21.21

#### Now, you can take the K-value of 21.21 and multiply it by the square root of 75 (representing a nozzle pressure of 75). 21.21 * 8.66 = 184 GPM. We get this value by working the formula to solve for flow instead of the K-value.

• K = flow/ √NP

• 21.21 = flow/ √75

• 21.21 = flow/8.66

• Flow = 21.21 * 8.66

• Flow = 184

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