Chapter # 9 Fireground Hydraulic Calculations Flashcards Preview

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Flashcards in Chapter # 9 Fireground Hydraulic Calculations Deck (41):

Name six fire ground hydraulic calculation methods.

Flowmeter. Hydraulic Calculators. Pump Charts. Hand Method. Condensed "Q" Formula. GPM Flowing.


T or F The number displayed on the flowmeter requires no further calculation because it reflects how much water is moving through the discharge valve and consequently the nozzle. This quantity of water only diminishes before it reaches the nozzle if there is a leak or break in the hoseline.



Flowmeters are particularly advantages when supplying hoselines or master stream devices equipped with what?

Automatic Nozzles.


T or F Flowmeters make it possible for drivers to pump the correct volume of water without having to know what?

Hose length. Friction Loss. Elevation pressure.


NFPA 1901 allows flowmeters to be used instead of pressure gauges on what size of discharges?

1 1/2" to 3"


NFPA allows flowmeters to be placed on discharges that are 3 1/2" or larger but they also must have what?

A pressure gauge.


What increment of gpm must be on a flowmeter?

no larger then than 10


Name the two most common type of flowmeters in the fire service.

Paddlewheel and Spring Probe


Mounted in the top of a straight section of pipe, very little extends into the waterway. Placement reduces problems with impeded flow and damage by debris. Sediment doesn't affect it due to being at the top of the pipe.

Paddlewheel flowmeter.


Uses a stainless probe to sense water movement. The greater the flow, the more the probe bends. The bending sends a digital signal to a display. Relatively maintenance free due to probe being the only moving part.

Spring Probe flowmeter.


Flowmeters should be accurate to a tolerance of what?

+/- 3%


How close to the discharge is the flow digital display?

Within 6"


What information is provided by a central flowmeter?

The flow through any particular discharge at that time. Total amount of water being flowed through the pump at that time. The total amount of water that has been flowed through the pump for the duration of the incident. The amount of foam being flowed.


Name three incidents when a flowmeter is especially useful to a driver.

Diagnosing water problems. Relay Operation. Standpipe operations.


What is a advantage of having a flowmeter when performing a relay operation?

You do not need to know the number of gallons flowing from the pumper receiving the water?


How do you use a flowmeter when supplying a pumper in a relay operation?

Increase the engine speed until the flowmeter reading no longer increases. This sets the pump at the correct discharge pressure pressure to supply an adequate flow to the receiving pumper.


How do you use a flowmeter when operating at a standpipe operation?

Determine the number and type of nozzles attached to the standpipe, adding the maximum rated flow for each nozzle flowing , and then pumping the volume of water that matches the figure.


Why is communication between the driver and firefighters important during stand pipe operations especially when using a flow meter?

When one or multiple nozzles is shut off it will send the flow to the other nozzles, possibly making the lines hard to handle.


Name the two types of hydraulic calculators.

Manual (mechanical) and Electronic


What information is used to determine PDP when using a manual hydraulic calculator?

Water flow. Hose size. Hose length.


What information is inputted into a electronic hydraulic calculator?

Water flow. Size of hose. Length of hose. Elevation change.


Most electronic hydraulic calculators calculate flow pressure requirements and not what>

Friction loss for a specific hose being used.


What is the first step in developing a pump chart?

Identify all nozzles, devices, and layouts used by the department and enter them in the nozzle column.


When developing a pump chart what should PDP's be rounded to?

The nearest 5 psi.


What finger do you start with when using the hand (counting fingers) method.

Thumb of the left hand.


On the hand method using 2 1/2" hose, what is at the base of the finger? What is in between each finger base.

Hundreds of gallons per minute. The next 50 gpm up from the previous finger. 100,150,200,250,300,350,400,450,500


On the hand method using the 2 1/2" hose, what is at the tip of each finger? What is in between each finger?

A even number starting with 2 at the thumb. A odd number that comes after the previous even number.


How do you determine FL in a 2 1/2" hose when using the hand method.

Select flow, select corresponding whole number, multiply whole number by the first number in the flow. Gives FL per 100'. EX 100gpm x 2. 1 x 2=2psi FL/100' EX 250gpm x 5. 2.5 x 5 = 12.5 FL/100'


What is at the tip of the finger when using the 1 3/4" hand method?

A sequential whole number starting with 1 at the thumb.


What is at the middle of the finger when using the 1 3/4" hand method?

A sequantial flow in gpm in quarters. Starting with 100 gpm at the thumb. 100,125,150,200


What is at the base of each finger when using the 1 3/4" hand method?



How do you determine FL per 100' in 1 3/4" hose using the hand method?

Find finger with the flow, multiply the corresponding number at the tip of that finger with the base 12. EX 100gpm = 1 x 12 =12 psi FL/100'. EX 175 gpm = 4 x 12 = 48 psi FL/100'


What size of hose can the condensed Q method be used?

3,4,and 5.


What is the condensed Q formula for 3" hose"? Can be used for either 2 1/2" or 3" couplings.

FL per 100' = Q^2


How much greater will the FL be if using the condensed Q formula for 3" hose then if using CQ^2L?



What is the condensed Q formula for 4" hose?

FL per 100' = Q^2/5


What is the condensed Q formula for 5" hose?

FL per 100' = Q^2/15


The gpm flowing method can be used on what type of nozzles?

Both fog and solid.


The gpm method applies to 2 1/2" hose flowing at least how much gpm?

160 gpm


How do you use the gpm flowing method with 2 1/2" hose?

minus 10 from the first two numbers in the gpm.


How do you use the gpm flowing method for 1 1/2" hose?

Flows of 50-75 gpm = mutiply the flow by 4 then subtract the first two numbers by 10.
Flows of 80-100 gpm = For every increase of 20 gpm the FL increase 3 psi.
Flows of 105-125 gpm = For every increase of 20 gpm FL increase 4 psi.