Chapter 16 Fire Streams Flashcards
The primary way that water extinguishes fire is by absorbing heat which creates what?
A cooling effect
The amount of energy required to raise the temp of a specific unit mass of a material 1 degree in temp.
Specific Heat
Quantity of heat absorbed by a substance at the point at which it changes from a liquid to a vapor.
Latent heat of vaporization.
How many more BTU’s are required to convert water into steam after it has reached its 212F boiling point?
970 BTU’s
At 212 F water expands how many times to turn into steam?
1700
Would a solid stream or fog stream nozzle cause water to convert into steam more quickly?
Fog stream. More surface area to absorb more heat.
When water turns to steam from striking a solid object (ceiling) that is 212 F, the steam will expand pushing the smoke layer down. What happens if the water turns to steam while traveling through the smoke layer?
The smoke layer will cool and contract.
T or F There is a practical limit to the velocity or speed at which water can travel through a hoseline. If the velocity is increased beyond this limit, the friction becomes so great that the water in the hoseline is agitated by the resistance.
True
Name ways that friction loss is reduced.
Increasing hose size. Adding additional parallel lines. Increasing pump pressure. Taking kinks or sharp bends out of the hoseline.
At low flow pressure water hammer is minimal. At higher flow rates the effects of water hammer do what?
Increase significantly.
What two ways are fire streams classified?
By their size and type.
What are the three sizes of fire streams?
Low-volume stream. Handline Stream. Master Stream.
Discharges less then 40gpm. Supplied by 3/4, 1 or 1 1/2” line.
Low Volume Stream
Supplied by 1 1/2” to 3” hose with flows from 40-350 gpm.
Handline Stream
Greater then 350gpm. Supplied by one or more 2 1/2” or 3” lines or LDH. Nozzle pressure of 80-100.
Master Stream
The minimum flow rate at which extinguishment can be achieved.
Critical Flow Rate
This indicates a specific pattern or shape the stream has as it leaves the nozzle.
The Type
Name the four types of fire streams.
Solid, Straight, Fog, Broken.
Stream as compact as possible. Has the ability to reach areas that other streams might not reach. Ability to penetrate materials.
Solid Stream
What two things determine the performance of a solid stream?
The velocity of the stream caused by the pump and the size of the nozzle orifice.
What nozzle psi can a solid stream handline be increased to when greater reach and volume are needed?
65 psi
Exposes the max amount of water droplets to absorb heat. Performance is based on the amount of heat the stream absorbs and the rate the water from the stream is converted into steam. Typically has a nozzle pressure of 100 psi. Increases in nozzle pressure do not increase reach but may increase flow.
Fog Stream
A semi solid stream that is produced by a fog nozzle.
Straight Stream
Stream of water that has been broken into coarsely divided drops.
Broken Stream
Name some characteristics of a broken stream.
Absorb more heat per gallon then a solid stream. Greater reach and penetration then a fog stream. Effective on fires in confined spaces. May conduct electricity. Stream may not reach some fires.
Name five limiting factors of fire streams.
Gravity. Water Velocity. Fire stream pattern. Water droplet friction with air. Wind.
Effective forward velocity of the fire stream ranges from what to what? and at what range of nozzle pressure?
60-120 feet per second. 25-100 nozzle pressure.
Under ideal circumstances what angel provides the max horizontal reach of a fire stream?
In actual operation what angle provides the max horizontal reach?
Ideal = 45 degrees. Actual = 30-34 degrees.
Standard for fire hose connections
NFPA 1963
What are the two categories of fire stream nozzles according to NFPA 1963 ?
Straight tip and Spray Nozzles
What are the three functions of any fire stream?
Controlling water flow. Creating reach. Shaping the fire stream.
The smooth bore nozzle tip should not be larger then what?
1/2 the diameter of the hose.
Can smooth bore nozzles be used to apply compressed-air foam?
Yes
The length of a smooth bore nozzle is how many times bigger then its inside diameter?
1 to 1 1/2 times
The flow rate of a smooth bore nozzle depends on what two things?
The pressure at the tip and the size of opening at the tip.
What three patterns can fog nozzles be adjusted to?
Straight stream. Narrow angle fog. Wide angle fog.
Name the four types of fog nozzles used in the fire service.
Basic fog nozzle. Constant Gallonage fog nozzle. Constant Pressure (Automatic) fog nozzle. Constant/Select gallonage fog nozzle.
A adjustable pattern fog nozzle in which the rate discharge is delivered at the designated nozzle pressure and setting.
Basic Fog Nozzle
Discharges a constant discharge rate throughout the range of patterns from the straight stream to a wide fog at a designated nozzle pressure.
Constant Gallonage Fog Nozzle.
The pressure remains relatively constant throughout a range of discharge rates.
Constant Pressure (Automatic) Fog Nozzle.
Allows manual adjustment of the orifice to effect a predetermined discharge rate while the nozzle is flowing.
Typically allows adjustments from 10-250 gpm on handlines and 350-2500 gpm on master streams. Also most have a flush setting.
Constant/Select Gallonage fog nozzle.
Automatic fog nozzles are designed for the following flow rates.
Low flow= 10 - 125 gpm
Mid-range flow = 70 - 200 gpm.
High Flows = 70 -350 gpm
Master streams = 350 - 1250 gpm.
Name three types of broken stream nozzles.
Piercing. Bresnan. Rockwood Cellar Pipes.
Used to access fires in concealed spaces. Can pierce stucco, block, wood, and lightweight steel.
Piercing Nozzle