Nozzle Reaction

Fog Nozzle Reaction

Estimate reaction force from fog-nozzle flow and nozzle pressure.

What It Tells You

The approximate reaction force from a fog stream.

Formula

NR = 0.0505 × GPM × √NP

What the Variables Mean

NR
nozzle reaction pounds
GPM
flow gallons per minute
NP
nozzle pressure PSI

Plain-Language Explanation

More flow creates more pushback. Higher nozzle pressure also increases reaction, though not in a one-for-one relationship.

Worked Example

Flow 150 GPM at 75 PSI NP.

  1. NR = 0.0505 × 150 × √75
NR ≈ 66 lb

Fireground Takeaway

Match the intended flow and nozzle pressure instead of treating every fog nozzle as the same package.

Practice This Formula

Open Reverse Flow and start a Practice Quiz filtered to this topic.

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