Chapter 10 Flashcards
Some apparatus have what feature if the parking brake has not been set, in regards to pumping?
A feature that prevents the pump from throttling up, or shifting into pump gear if the parking brake has not been set
What are the two basic pressurized water supply sources?
Hydrant and supply hose from another pumper
The least desirable type of hydrants, served by smaller mains from only one direction. And usually have a higher amount of sediment and deterioration.
Dead end mains
Pressure decreases .5psi for every how many feet of altitude gain?
Every 1000ft
The driver/ operator should realize when the pump nears this number of inches of mercury the pump is nearing its limits of its ability to supply water?
Most pumps are able to develop a vacuum capacity of approximately 22 inches of mercury. Any reading close to this point indicates the pump is nearing the limits of its ability to supply water
Cavitation can be described as?
Water being discharged faster than it can it is coming into the pump
What are some indicators of pump cavitation?
The pressure gauge will fluctuate, and hose streams may pulsate creating a distinctive popping or sputtering sound as water leaves the nozzle. In severe cases the pump itself may sound like gravel is passing through the pump. Surest indication is lack of reaction on the pressure gauge to increases in the throttle.
In order for a pumper to approach its rated capacity using a traditional strainer, there must be how many inches of water over the strainer?
24 inches, it is helpful to have 24 inches all around in order to avoid drawing foreign objects such as sand and gravel into the pump
In order for a floating strainer to work properly, it must?
Be able to float freely, unconstrained by the rigidity of the intake hose
What must the driver operator think of in regards to using a floating strainer in regards to discharge capacity?
The pumper may not receive enough water to achieve its rated discharge capacity
Water below this temp and above this temp will adversely impact the ability of the pump to reach capacity?
Below 35 F and above 90 F
True or false pumping no potable water can be harmful to the pump?
True
Each time nonpotable water is pumped through the apparatus, what should be done?
The pump and piping should be throughly flushed with fresh water soon afterwards
A pumper in good working order can lift water a max of how many feet?
25 ft
To create an effective water stream, a lift of no greater than how many feet is recommended?
No greater than 20 ft, working with this lift, the pump operates at about 60% of its rated capacity
What are important considerations during draft site selection?
Stability of the ground surface, the conscience of connecting hose lines, and the safety of the driver operator.
For two stage pumps, the transfer valve must be in what position?
In parallel (volume) position. A pump in series (pressure) position may trap air that will need to be removed
Most priming pumps are intended to work most efficiently when the engine is set at a rate between?
1000 and 1200 rpm
If the apparatus features a vacuum type primer, the engine rpm should be set to?
As low as possible without causing the engine to stall
As the primer operates, the vacuum reading should?
Increase as atmospheric pressure forces water into the intake hose
The entire priming action typically requires how much time?
10 to 15 seconds from start to finish, when up to 20 ft of intake hose lifting a max of 10 ft it may take as long as 30 seconds (45 seconds) in pumps larger than 1250 gpm
What is the most common cause of air leaks?
Open drain or valve
What should be done after successfully priming the pump?
Throttle setting should slowly be increased before attempting to open any discharges. This is required to increase the pressure between 50-100 psi.
True or false without moving water, even a small air leak may result in a loss of vacuum?
True
While the pump is operating, a gradual increase in the vacuum may be noted with no change in flow rate, this is an indication of?
A blockage is developing
Where is the most common place for a blockage to occur?
In the strainer
How should you shut down a drafting operation?
Slowly decrease the engine speed to idle, take the pump out of gear, and allow the pump to drain. After the pump is drained and connections removed, operate the positive displacement primer for several seconds until the primer oil or fluid comes out of the discharge from the priming pump. Flush pump unless using a very clean static water supply
