Flashcards in Chapter 10 - Operating Fire Pumps Deck (25)
Driver/operators should maintain a residual pressure of at least ___ psi on their master intake gauge at all times during pumping operations.
A ________ ___ consists of stopping at the hydrants, dropping the end of one or more supply hoselines at the hydrant, and then proceeding to the fire location.
With the ________ ___, hose is laid from the fire to the water source.
Several methods for preventing overheating are as follows:
> Establish a continuous minimum flow during intermittent use of water in firegound operations to keep the pump from overheating.
> Pull a length of the booster line or other small diameter line off the reel and fasten it to a sturdy object.
>Open the valve that supplies the booster reel and discharge water in a direction that will not interfere with the operation or damage other property. The booster line may also be directed back into the tank to circulate water continuously.
> Open a discharge drain valve.
> Partially open the tank-fill valve or tank-to-pump line.
When the pumper is discharging water, the intake gauge displays the residual pressure. The difference between the two pressures is used to determine how much more water the hydrant can supply. Several methods are available for making this determination:
> Percentage Method
> First-Digit Method
> Squaring-the-Lines Method
Percentage Drop Equation
Percentage Drop = (Static-Residual)(100) divided by Static
0-10 - 3 Times
11-15 - 2 Times
16-25 - Same Amount
25+ - 0
First Digit Method
> (Static - Residual) = X
> First-digit of Static times 1, 2, or 3 = Y1, Y2, Y3
> If X is <= Y1 -----> 3 additional lines
> If X is <= Y2 -----> 2 additional lines
> If X is <= Y3 -----> 1 additional line
Atmospheric pressure decreases approximately ____ psi or __ in Hg for every _____ feet of altitude gain.
0.5 psi or 1 in Hg
Most pumps are able to develop a vacuum capacity of approximately ___ in Hg
22 in Hg
The _________ of the water, the ______ of the lift, and the _______ __ ______ being dischared affect the point at which cavitation begins
Amount of Water
A drafting site may be selected by:
> Amount of water
> Type or quality of water
> Accessibility of water
The most important factor in choosing a draft site is the ______ __ ______ ______.
Amount of water available
In order for a pumper to approach its rated capacity using a traditional strainer, there must be at least ___ inches of water over the strainer.
As the amount of lift required to reach the pump increases, the following effects occur:
> Elevation pressure increases
> Less friction loss can be overcome
> Capacity of the pump is decreased
A pumper in good working order can lift water a maximum of ___ feet.
To create an effective fire stream, a lift no greater than ___ feet is recommended.
Other important variables to consider during draft site selection include:
> The stability of the ground surface
> The convenience of connecting hoselines
> The safety of the driver/operator
Most priming pumps are intended to work effectively when the engine is set at a rate between _____ and _____ rpm.
1,000 and 1,200 rpm
As the air is evacuated from the pump the master intake gauge will register a vacuum reading. this reading should equal __ in Hg for __ foot of lift.
1 in Hg for 1 foot
The entire priming action typically requires ___ to ___ seconds from start to finish. However, when up to ___ feet of intake hose lifting a maximum of ___ vertical feet, it may take as long as ___ seconds (___ seconds for pumps larger than 1,250 gpm) to accomplish this.
10 to 15 seconds
Several types of problems occur during drafting operations:
> Air leak on the intake side of the pump. (Most common source of problems)
> Whirlpool allowing air to enter the pump.
> Air leakage due to defective pump packing.
The actual capacity of the pump is determined in a given scenario by the ______ and ______ of the intake hose, the _______ design, and the _______.
Diameter and length
If no specific information is available, the general guideline is to discharge ____ psi into the FDC.
Pump discharge pressure will depend on the following variables:
> Pressure loss (25 psi in the standpipe)
> Friction loss in the hose lay from the pumper to FDC.
> Friction loss in the hose on the fire floor.
> Nozzle pressure for the type of nozzle used.
> Elevation pressure due to the height of the building.