Jet Stream

What Is Jet Stream?

In fireground hydraulics, a jet stream (solid stream or straight stream) is a high-velocity, compact water stream produced by a smooth-bore nozzle or tight fog nozzle, designed for maximum reach, penetration, and wind resistance during heavy fire suppression.

Why Jet Stream Matters on the Fireground

Solid jet streams penetrate deep into large fire compartments, reaching the seat of the fire through heavy smoke and heat without breaking into fine spray that evaporates prematurely. Solid streams also minimize air entrainment compared to wide fog streams.

Relevant NFPA Standards

• NFPA 1010: Standard on Professional Qualifications for Firefighters
• NFPA 1550: Standard for Emergency Responder Health and Safety

Field Procedures & Tactical Steps

1. Select a smooth-bore nozzle or adjust fog nozzle pattern to narrow straight stream.
2. Verify proper operating nozzle pressure (50 PSI for smooth-bore handlines, 80 PSI for master streams).
3. Aim stream at the ceiling above the fire seat to allow water droplets to rain down over fuel bed.
4. Use solid stream reach to attack fire from outside the collapse zone when operating defensively.
5. Shut down nozzle bail slowly to avoid severe water hammer in the supply line.

Common Context & Application

Utilized for exterior master stream operations, high-rise standpipe attacks, commercial structure fires, and penetrating dense fuel piles.

Frequently Asked Questions about Jet Stream