Chapter 11, Operating Fire Pumps Flashcards
IFSTA recommends that the apparatus wheels be chocked when ?
Every time the apparatus is stopped with the engine running and driver operator exits the cab (in case truck jumps into gear).
How can water be allowed to circulate in the pump, if no attack line is ready by the time pump pressure has built up?
Crack open the “tank fill”.
If the master pressure gauge fails to register a reading (after you have put truck in pump), what would you check?
Pump may not be in proper gear. Immediately decrease rpm, go to cab and ensure transmission is in proper gear.
What are the 2 basic pressurized water supply sources, that can be used to supply a fire pump?
- hydrant
- supply hose from another fire pump
What happens if the discharge pressure from the pump is increased too much?
The intake pressure from the supply source may be reduced below zero (cavitation).
To avoid possible damage to the fire pump, you should not allow the intake pressure fall below how much psi?
20psi (in rare instances, you may have to, but should never fall to zero).
What is the first consideration when selecting a hydrant?
Determining which hydrant is most appropriate in terms of fire fighting and safety needs (The closest hydrant is not always the best choice).
What are the 2 ways that a fire department pumper may use a hydrant?
- forward lay (stopping at hydrant, drop supply line at hydrant, proceed to fire)
- reverse lay (laying hose from fire scene back to hydrant)
Departments that prefer forward lays use a 4 way hydrant valve. Why?
The valve (humat) has a 2nd discharge outlet, which allows a 2nd pumper to connect to the hydrant without interrupting flow (boosts pressure to initial pumper).
When using the 2 1/2 or 3 inch lines to supply the pumper directly from the hydrant, its recommended that the lines not be any longer than 300 feet. Why?
Beyond 300 feet, the amount of friction loss is to great to provide an adequate supply of water.
What hose lay is used as the most direct way to supplement hydrant pressure and perform drafting operations?
Reverse lay.
What are 2 disadvantages of reverse lay?
- fire fighting equipment must be removed and placed at fire location before pumper proceeds to hydrant (time consuming)
- pumper may not carry enough hose to reach from fire to water source
What are some methods of preventing overheating?
- pull off/secure booster line, open valve
- open discharge drain valve
- partially open the tank fill valve
- use circulator/bypass valve (if truck has one)
What 3 methods are use to determine “additional lines” available?
- percentage method
- first-digit method
- squaring the lines method
How do you check to see, after shutting down a dry hydrant, if the water is draining?
Cover a 2 1/2 outlet with your hand, if the hydrant is draining, a slight vacuum will be felt.
The first consideration in establishing a drafting operation is selecting a site. What factors dictate the site selected?
- amount of water (most important)
- type of water
- accessibility of water
How much water is recommended around the strainer during a drafting operation?
Minimum 2 feet of water over the strainer (desirable to have 2 feet all around the strainer). Helps to ensure max capacity and avoid drawing objects into pump (sand, gravel).
What 2 methods are used to draft from a swiftly moving shallow stream?
- use a floating strainer (preferred)
- construct a dam
During drafting operations, what is the most common, and most dangerous, type of contamination?
Dirty or sandy water.
During drafting, as the amount of lift increases, what occurs?
- elevation pressure increases
- less friction loss can be overcome
- capacity of the pump decreases
What are pump capacity ratings based on, for drafting?
A 10 foot lift.
For effective drafting operations, what is the maximum lift considered reasonable for most fire department pumpers?
About 20 feet (at 20 ft, amount of water that can be supplied is only about 60% of the pumps rated capacity).
Once the drafting operation is physically set up, what starts the draft operation?
Priming the pump.
When do you stop the priming action?
When all the air is removed and the primer is discharging a steady stream of water.
How long does the entire priming action typically take?
10 to 15 seconds from start to finish.
What are the causes for inability to prime a pump?
- air leak (most common)
- insufficient fluid in priming reservoir
- rpm too slow
- lift is too high
- high point in the hard intake hose creating an air pocket
The problems that can occur while drafting falls into what 3 categories?
- air leak on intake side of pump (most common)
- whirlpool allowing air to enter the pump (not enough water over the strainer
- air leak due to defective packing in the pump
What’s the first line of defense against uncontrolled fire within an occupancy?
Fixed fire protection systems (sprinkler/standpipe).
What does and FDC consist of?
A siamese with at least 2 2 1/2 inch female connectors, or one large diameter sexless connection.
What are standpipes used for?
To speed fire attack in multistory or single story buildings with large floor plans.
During standpipe operations, pump discharge pressure depends on what?
- pressure loss in the standpipe
- friction loss in the hose lay from pumper to FDC
- friction loss to hose on fire floor
- elevation pressure due to height of building
- nozzle pressure for type of nozzle used
Pump discharge pressures for standpipes in the city of Glendale are standard 150 psi. What pump discharge pressure, in general, are we encouraged not to exceed?
Pump discharge pressures in excess of 200 psi are not encouraged, unless the standpipe system is designed to withstand higher pressures.
When a standpipe system is known to be equipped with pressure reducing valves, the elevation pressure used must be based on what?
Based on the total height of the standpipe or the zone being used.
