Which is a characteristic of water as an extinguishing agent?
Water has a higher specific heat than most common substances, and this is one of the reasons it is such an effective extinguishing agent. Think of how much energy it takes to heat a liter of water to a boiling point every time you put on a kettle.
What two factors determine the volume of water discharged by a fire stream?
The volume of water discharged is determined by nozzle design and water pressure. Fire stream type is the pattern or shape of the stream as it leaves the nozzle. Several components are required for a fire stream to be effective. A solid stream is produced from a fixed orifice and a smooth bore nozzle.
Which fire stream pattern is usually produced by a fog nozzle?
All styles of fog nozzles have a spray pattern adjustment. These nozzles can produce three different types of streams; the straight stream for long reach, the narrow-angle cone for advancing an attack line into a structure or fire room, and the wide-angle cone for protection and ventilation.
Which of the following will cause the upper layer of hot smoke and fire gases in a compartment to expand downward?
Steam produced in the upper layer of hot smoke and fire gases may cause the upper layer to expand downward. … Steam produced on contact with hot surfaces is more likely to result in complete vaporization of the fire stream.
When water fog is used as an extinguishing agent the fire is extinguished principally by the?
Water and foam fire extinguishers extinguish the fire by taking away the heat element of the fire triangle. Foam agents also separate the oxygen element from the other elements. Water extinguishers are for Class A fires only; they should not be used on Class B or C fires.
What type of fire should water be used on?
WATER. Water fire extinguishers have a red label and a class A rating. They are suitable for fighting fires involving solid combustibles such as wood, paper and textiles.
What are three types of fire streams?
1. Solid stream 2. Fog stream 3. Broken stream
- Solid stream.
- Fog stream.
- Broken stream.
What is elevation pressure in firefighting?
Elevation Pressure: Pressure that is gained or lost due to elevation (. 434 psi rounded up to . 5 psi per foot). Engine: Also known as a “Pumper”.
Which factor affects the condition of a fire stream?
A stream of water or other extinguishing agent after it leaves a fire hose nozzle until it reaches the desired target. When passing through air, a fire stream is affected by what 4 things? it’s velocity, gravity, wind, and friction with air.
What is a fire stream?
Fire streams are used to reduce the heat from a fire and provide protection to firefighters and exposures. … A fire stream is a stream of water between the fire nozzle and the target. It is not possible to provide a more precise definition of a fire stream since different fire streams are created for specific purposes.
Which of the following is a method by which foam extinguishes a fire?
Unlike other extinguishing agents – water, dry chemical, CO2, etc., a stable aqueous foam can extinguish a flammable or combustible liquid fire by the combined mechanisms of cooling, separating the flame/ignition source from the product surface, suppressing vapors and smothering.
Which is an advantage of an automatic adjusting fog nozzle?
What is an advantage of an automatic fog nozzle? The flow rate adjusts to maintain the rated nozzle pressure.
What are the causes of fire explain the basis of components?
A fire needs three elements – heat, oxygen and fuel. Without heat, oxygen and fuel a fire will not start or spread. A key strategy to prevent fire is to remove one or more of heat, oxygen or fuel. … Advice on these three elements follows.
Which of the following will cause the upper layer of hot smoke and fire gases to contract toward the ceiling?
Steam produced in the upper layer of hot smoke and fire gases will cause the upper layer to contract toward the ceiling. Which of the following statements about friction loss is MOST accurate? … friction loss.
What is basic chemistry of fire?
Flames consist primarily of carbon dioxide, water vapor, oxygen and nitrogen. If hot enough, the gases may become ionized to produce plasma.