IFSTA Chapter 10 Operating Fire Pumps Flashcards
When operating at the pump panel, drivers must wear
full PPE
What does the placement of chocks provide
an extra measure of safety should the apparatus jump into road gear or override the parking brake system
When operating the pump when should you reach the appropriate pressure
When water is flowing
When using the tank fill valve to cool the pump what must be concidered
Tank Fill Line may be piped large enough to cause the pump to cavitate when using the onboard tank
When discharge pressure increases, intake pressure from the source will drop due to friction loss,
what happens when intake pressure drops too low
Why must you not pump below a residual pressure of 20 psi while being supplied
Allowing the discharge pressure to decrease the intake from the source can cause damage to the pump
pumping at a residual pressure below 20 psi while being supplied by other apparatus may cause the supply line to collapse or lead to cavitation
Why should supply systems maintain a residual pressure of 20 psi also
Contamination from sources outside the main may occur
overtaxing the water system may cause sediment or debris that has formed to become lose and damage the pump
what are dead end hydrants and why are they least desirable source
Hydrants served by smaller mains from only one direction and generally have higher amounts of sediment and deterioration
In Prolonged pumping operations a bypass circulator may not provide enought cooling, what other methods can be used to keep the pump from overheating
Open Discharge Drain Valve: Some need opened before valve is under pressure
Partially open tank-fill valve or tank to pump
Exact explanation of Like Volumes
10% of less = 3 lines of the same flow can be added
11 - 15% = 2 lines of the same flow can be added
16 - 25% = 1 lineof the same flow can be added
more than 25%= more water may be available but not as much as is flowing through first line
A_______ _____ is created when air inside the pump is evacuated
Pressure Differential
allows atmospheric pressure acting on the surface of the water to force water into the fire pump
With an atmospheric pressure at sea level of 14.7 psi what is a partial vacuum of -2 psi measured as
4” of mercury which causes water to rise 4.6ft
The Weight of water combined with reduced air pressure creates a balance
When drafting other than bends in plumbing, hose or appliance what else created friction loss
The Inertia of water
To what level of mercury are pumps able to develop a vacuum approximately
22” of mercury but
Compound gauges not providing accurate readings on the vacuum side it must be acknowledged that at this reading the pump is nearing the limits of its ability to supply water.
Describe cavitation
Water being discharged faster than it is coming into the pump
What causes cavitation
(Air cavities)
Air cavities are created in the pump as they move from highest vacuum into the presurized section where they collapse (fill with water)
High velocity of these cavities filling causes severe shock to pump
What occurs to the state of water during cavitation
Pressure drops below atmospheric and the boiling point of water drops to the point that water changes to a vapor creating voids of steam