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Ray - Chapter 14
| Question | Answer |
|---|---|
| 2 Factors that affect pressure loss and gain | friction loss and elevation loss |
| Friction loss | that part of total pressure that is lost while forcing water through pipes, fittings, fire hose, and adaptors |
| Elevation Loss/gain | 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 difference in elevation |
| Low - volume stream | discharges less than 40 gpm (160 L/min) including those fed by booster lines. Typically supplies by 3/4 - inch (20 mm), 1-inch (25 mm) or 1 1/2 inch (38 mm) hoselines |
| Handline stream | Supplied by 1 1/2 inch to 3 inch (38mm to 77 mm) hose, with flows from 40 to 350 gpm (160 L/min to 1 400 L/min) Nozzles with flows in excess of 350 gpm are not recommended for handlines |
| Master stream | Discharges more than 350 gpm (1 400 L/min) and is fed by 2 1/2 or 3 inch (65 mm or 77 mm) hoselines or large-diameter hoselines connected to a master stream nozzle. Master streams are large - volume fire streams |
| Solid stream | fire stream produced from a fixed orifice, solid-bore nozzle - designed to produce a stream as compact as possible with little shower or spray - has the ability to reach areas that other streams may not reach |
| Disadvantages of Solid stream | do not allow for different stream pattern selections, provide less heat absorption per gallon (liter) delivered than other types of streams, Hoselines more easily kinked at corners and obstructions |
| Fog stream | A fine spray composed of tiny water droplets - water droplets in either a shower or spray are formed to expose the maximum water surface for heat absorption - fog nozzle permits settings of straight stream, narrow angle fog and wide angle fog |
| 5 factors that affect the reach of a fog stream | gravity, water velocity, fire stream pattern selection, water droplet friction with air, wind |
| Waterflow adjustment has 2 type of nozzels | Manually adjustable nozzles and Automatic (constant pressure) nozzles |
| Manually adjustable nozzles | rate of discharge from this nozzle can be changed by rotating the selector ring - usually located directly behind the nozzle tip |
| Automatic (constant-pressure) nozzles | automatically varies the rate of flow to maintain a reasonable constant nozzle pressure through a specific flow range |
| Advantages of fog streams | discharge pattern of fog streams can be adjusted to sure the situation, fog streams can aid ventilation, fog streams reduce heat by exposing the maximum water surface for heat absorption, fog streams can provide protection for firefighters with wide fog |
| disadvantages of fog streams | fog streams do not have as much reach or penetrating power as solid streams, more affected by wind than are solid streams, may disturb thermal layering in a room or compartment if applied incorrectly, may push are into the fire area |
| Broken stream | one that has been broken into coarsely divided drops |
| Advantages of broken stream | coarse drops absorb more head per gallon (liter) than a solid stream, have greater reach and penetration than a fog stream, can be effective on fires in confined spaces such as attics and wall spaces |
| Disadvantages of broken stream | may have sufficient continuity to conduct electricity so are not recommended for use on Class C fires, stream may not reach some fires |
| foam concentrate | raw foam liquid before the introduction of water and air |
| foam proportioner | device that introduces foam concentrate into the water stream to make the foam solution |
| foam solution | mixture of foam concentrate and water before the introduction of air |
| foam (finished foam) | completed product after air is introduced in the foam solution |
| Foam application techniques - Roll-on Method | Directs the foam stream on the ground near the front edge of a burning liquid spill - the foam rolls across the surface of the fuel - foam is applied until it spreads across the entire surface and the fire is extinguished |
| Bank-Down method | when an elevated object is near or within the are of a burning pool of liquid or an unignited liquid spill - foam is directed onto the object allowing the foam to run down and onto the surface of the fuel |
| Rain Down method | used when the other 2 methods are not feasible because of the size of the spill or lack of an object on which to bank the foam primary method used on above ground storage tank fires - foam is directed into the air above the fire or spill |
Created by:
amarler6