Chapter 14 Fire Streams Review Questions

Question 1

What are the ways that water can extinguish fire ?

Answer 1

Water can extinguish fire in several ways

• The primary way is cooling, which absorbs the heat from the fire
• Another way is smothering , which dilutes or excludes oxygen.

(pg.718)

Question 2

Define Friction Loss

Answer 2

Friction Loss - the part of total pressure that is lost while forcing water through pipes, fittings, fire hoses, and adapters.

The water molecules rub agaisnt the insides of these items and friction is produced. The friction slows the water flow and reduces its pressure

The most common example of friction loss, is the loss of pressure in a hoseline between a pumper and the nozzle.

(pg.722)

Question 3

What is Elevation loss/gain??

Answer 3

Elevation = refers to the position of a nozzle above or below the pumping apparatus

Elevation Pressure = refers to a gain or loss in hoseline pressure caused by gravity when there is a diference in elevation.

• When a nozzle is above the fire pump, there is a pressure loss.
• When the nozzle is below the pump, there is a pressure gain.

(pg.723)

Question 4

What is Water Hammer?

Answer 4

Water Hammer = When the flow of water through fire hose or pipe is suddenly stopped, such as by suddenly closing a nozzle, a shockwave is produced when the moving water reaches the end of the hose and bounces back; The resulting pressure surge is reffered to as water hammer.

• Can be heard as a distant clank
• It causes considerable damage to water mains, plumbing, firehose, hydrants and fire pumps

(pg.724)

Question 5

What factors can increase friction loss in fire hose ?

Answer 5

• Hose size , length o the hose lay. In general the smaller the diameter and the longer the hose lay, the higher the friction loss at a given pressure/flow rate
• Rough linings in fire hose
• Hoselines longer than necessary
• Damaged hose couplings
• Hose diamter too small for the volume needed
• kinks/sharp bends in hose
• more adapters than necessary

(pg.723)

Question 6

What are three size classifcations of fire streams ??

Answer 6

1. Low-volume streams = Discharges less than 40 gpm including those fed by booster lines. Generally 3/4 inch, 1 inch, and 1 ^1/2 inch.
2. Hand line streams = 1^1/2 inch to 2 inch hose with flows from 40 gpm to 350 gpm. Nozzles with flows in excess of 350 gpm are not recommeded on handlines.
3. Master Stream = Discharges more than 350 gpm and is fed by 2^1/2 to 3 inch hoselines or large-diameter hoselines connected to a master stream nozzle. *Master streams are large-volume fire streams. *

(pg.724 & 725 )

Question 7

What is the difference between a solid stream and a fog stream ?

Answer 7

A solid stream is a fire stream produced from a fixed orifice, solid bore nozzle.

Solid-stream nozzles are designed to produce streams as compact as possible with little shower or spray

. A solid stream has the ability to reach area that other streams might not reach.

_Solid streams are different from “straight streams” produced by fog nozzles. _

A Fog stream is a fine spray composed of tiny water droplets.

The design of most fog nozzles permit adjustment of the tip to produce different stream patterns from the nozzle.

Fog-nozzles permit settings of straight-stream, narrow-angle fog and wide angle fog.

• A straight stream is a pattern of the adjustable fog nozzle, wheras a solid stream is discharged from a solid-bore nozzle *
  (pg. 726,727,728)

Question 8

What are some advantages and disadvantages of a Solid Stream?

Answer 8

_Advantages _

• Better interior visiblity
• Greater reach
• Operates at reduced nozzle pressure per gallon, thus reducing the nozzle reaction
• May be easier to manuever
• Greater penetrating power
• Less prone to clogging with debris
• Less steam conversion
• Can be used to apply compressed air-foam

Disadvantages

• Does not allow for different stream pattern selections
• Less heat absorption per gallon delivered than other types of streams
• Hoselines more asily kinked at corners/obstructions

Question 9

What are some advantages and disadvantages of a Fog Stream

Answer 9

Advantages

• The discharge pattern of fog streams can be adjusted to suit the situation
• Fog streams can aid ventalitation
• Fog streams reduce heat by exposing the maximum water surface for heat absorption
• Fog streams can provide protection to firefighters with a wide fog pattern

Disadvantages

• Does not have as much reach or penetrating power as solid streams
• Fog streams are more affected by wind than solid streams
• Fog streams may disturb thermal layering in a room or compartment if applied incorrectly
• Fog streams may push air into the fire area, thus intensifying the fire

(pg.731)