Ch13 set 06:Fire Hose Streams: Types, Effects, and Application Techniques

What is a hose stream?

The flow of water from the supply through the nozzle toward the fire; it may include additives such as foam.

What factors affect a hose stream?

Velocity, flow, gravity, wind, air friction, operating pressure, nozzle design and adjustment, and the condition of its opening.

What direct cooling tasks can hose streams perform?

Cool burning materials, open flames, and upper gas layers, allowing extinguishment and line advancement.

What other protective or ventilation tasks can hose streams perform?

Disperse hot smoke and gases, create a protective water curtain or fuel/fire barrier, and perform hydraulic ventilation.

How are hose streams commonly described?

By their pattern, nozzle, flow-control valve, and limiting factors.

What determines nozzle flow, reach, and stream shape?

Orifice size and nozzle pressure determine flow; opening size influences reach; nozzle type determines shape.

What patterns do smooth-bore and fog nozzles produce?

Smooth bore produces a solid stream; adjustable-pattern spray or fog nozzles produce fog or straight streams.

Why is water a useful extinguishing agent?

It is available, relatively inexpensive, versatile, and has high heat-absorbing capacity and latent heat of vaporization.

How does water extinguish fire?

By absorbing heat.

What is vaporization?

The conversion of water into vapor or steam at its boiling point, with sufficient heat maintained to complete the change.

How much does water expand into steam at 212°F (100°C)?

Approximately 1,700 times its original volume; steam expands further as temperature increases.

What determines the amount and compartment effects of steam produced?

The amount of water applied determines steam volume; where steam is produced affects compartment conditions.

Why do smaller droplets absorb heat and vaporize faster than a solid stream?

They expose more water surface to heat.

What coordination improves hose-stream effectiveness and safety?

Good nozzle control coordinated with tactical ventilation.

What do hose-stream size and type describe?

Size is water volume per minute; type is the pattern or shape leaving the nozzle.

What are the three flow-based stream classifications?

Low-volume, handline, and master stream; discharge is measured in gpm or L/min.

What is a low-volume stream, and what hose supplies it?

Less than 40 gpm, typically through ¾-, 1-, or 1½-inch hose.

What flow and hose sizes define a handline stream?

40-350 gpm through 1½- to 3-inch hose.

What is the upper recommended handline flow?

350 gpm, including initial attack and backup lines.

How is a master stream defined?

More than 350 gpm, supplied by one or more 2½- or 3-inch lines or LDH; typical nozzle pressure is 80-100 psi.

What equipment produces master streams?

Devices such as apparatus-mounted deck guns and ladder pipes.

What must a stream accomplish to extinguish fire effectively?

Deliver enough water to absorb heat faster than the fire generates it, meet or exceed critical flow, and reach the target.

What four components are needed to produce a hose stream?

An agent such as water, a pump, a hoseline, and a nozzle.

What are the four principal stream patterns?

Solid, fog, straight, and broken; pattern and flow-size classifications are separate.

What are the main qualities of a solid stream?

A compact stream with little spray, long reach, rapid water delivery, and penetration and saturation of burning material or debris.

How can a solid stream be used to cool a compartment's gases?

Deflect it off a wall or ceiling to break it into droplets with greater heat-absorbing surface area.

What electrical hazard limits solid-stream use?

Do not use a solid stream on energized electrical equipment.

What is a stream's breakover point?

The point at which forward velocity is lost and the stream falls into spray readily affected by wind.

What characteristics describe an effective solid stream?

It remains continuous until breakover and sufficiently cohesive to retain shape and reach the required height in a light wind.

What pressure guidance is given for increasing solid-stream reach?

50 psi gives good reach and volume; it describes increasing to 65 psi for more reach and volume, with additional staffing needed above that pressure.

What is a fog stream?

A fine spray of tiny droplets that exposes a large water surface for heat absorption.

What characterizes fog-stream performance?

The amount of heat absorbed and the rate at which water becomes steam or vapor.

What applications can fog streams serve?

Hydraulic ventilation, vapor dispersion, crew protection, and cooling hot gases or surfaces.

What are the reach and wind limitations of fog streams?

Less reach and penetration and greater wind sensitivity than solid or straight streams.

What can incorrect fog-stream application do inside a compartment?

Disturb thermal layering or push fresh air into the fire and intensify it.

How do narrow- and wide-angle fog patterns differ?

Narrow fog has greater forward velocity and reach; wide fog has less velocity and shorter reach.

What is a straight stream?

A semisolid stream from a fog nozzle, with characteristics similar to a solid stream.

What is a broken stream?

Coarsely divided droplets formed as water leaves a specialized device; solid or straight streams can also be broken by deflection.

Where are broken streams used?

Attics, cocklofts, basements, and other confined spaces, including cooling hot gases above a fire.

How does gravity limit a stream?

It limits vertical and horizontal travel and causes a solid stream to separate and lose compactness.

How does velocity loss limit a stream?

Water slows as it travels; inadequate starting pressure limits reach.

How does air friction affect stream reach?

Drag affects fog droplets more than a solid stream; at equal pressure and flow, solid streams have the longest reach.

How does wind affect streams?

Wind speed and direction can shorten reach and distort shape, especially with fog.