Vol X 1012.10A Flashcards
Hydraulics is the branch of engineering which deals with what?
the properties of water or other fluids at rest and in motion
What are the 2 aspects that most students and practitioners of fireground hydraulics identify?
theoretical and practical
Define Static Pressure
the stored potential energy that acts equally in all directions in a fluid at rest
in other words: the pressure available from a hydrant or supply line before water is discharged from the apparatus
Define Residual Pressure
the part of the total available pressure that is not used to overcome friction or gravity while water moves through the pipe, fittings, fire hose, and adaptors
in other words: the remaining pressure from the hydrant after water begins flowing from the apparatus
Define Flow Pressure
the forward velocity pressure at a discharge opening while water is flowing
aka nozzle pressure
Define Key Pumper
pumper positioned on a hydrant that is relaying water pressure from the hydrant to pumpers positioned away from the water source
Define Forward Pumper
pumper (or pumpers) in an attack position near the fire and normally at a distance from the hydrant
Define “Unsupported” Position
a “forward” pumper which has laid a supply line in an attack position
a supply line is unsupported as long as it remains unpumped by a “key” pumper
Define “Supported” position
a “forward” pumper which is a “key” pumper relaying water pressure from the hydrant through a supply line to the “forward” pumper
What happens to the volume a pumper can deliver when it must produce a higher pressure level?
the volume goes down
What happens to the actual capacity of the pump when supplied by pressure from a good water source? i.e. hydrant pressure
actual capacity of the pump increases
Define Net Pump Pressure
a measure of the pressure energy that is actually produced by the pump
in other words: it is the difference between the pump discharge pressure and the incoming pressure
looking at the gauge….
pump discharge pressure minus intake pressure
What are the 2 ways to estimate hydrant availability?
- percent method
2. first digit method
Describe the Percent Method
look for the percent drop in pressure from static pressure to residual pressure
0 to 10% - 3 more like lines
11 to 15% - 2 more like lines
16 to 25% - 1 more like line
26% and up - some more water is available
Describe the First Digit Method
Take the static pressure and subtract the residual pressure to find the drop in psi
Look at the first digit of the static pressure. If first digit is….
Times 1 = 3 more like lines
Times 2 = 2 more like lines
Times 3 = 1 more like line
Times 4 or greater = some more water
What is the purpose of the hydraulic theories?
aimed to help the pump operator achieve and maintain proper engine pressure during pump operations
What does PDP stand for?
Pump Discharge Pressure
What formula is used to find PDP?
PDP= NP + FL + AP +/- EL
PDP= Pump Discharge Pressure NP = Nozzle Pressure AP = Appliance Value EL = Elevation
How many rpm for
Red line?
1 1/2”?
Fog Hog?
Red line - 30 gpm
1 1/2” - 250 gpm
Fog Hog - 1000 gpm
What is the nozzle pressure for all fog nozzles?
100 psi
What are the guidelines for max volumes through hand lines and the number of personnel required to operate those lines?
up to 125 gpm - 1 persons
125-250 gpm - 2 persons
250-350 gpm - 3 persons
All lines flowing greater than 200 gpm are considered what?
When must these lines be shut off in regards to repositioning the line?
“Stationary” lines
must be shut of BEFORE repositioning
What is the MAXIMUM gmp for any handling at any time?
350 gpm
Common master stream diameters and flows: 1 1/4 inch = 400 GPM 1 3/8 inch = \_\_\_\_\_ GPM 1 1/2 inch = \_\_\_\_\_\_ GPM 1 5/8 inch = 700 GPM 1 3/4 inch = \_\_\_\_\_ GPM 1 7/8 inch = 900 GPM 2 inch = \_\_\_\_\_\_ GPM Control/fog nozzle = \_\_\_\_\_\_\_\_GPM
1 3/8" = 500 1 1/2" = 600 1 3/4" = 800 2" = 1000 Fog = 1000
What does the “rule of eights” help you find?
the gpm flow through solid stream tips on master stream appliances
What does the “rule of 8’s” state?
that if the fraction of the tip being used is put in a common denominator of 8, and then 2 is added to the numerator, the result will be the first digit of the approximate flow of the nozzle
ex: 1 1/2 = 1 4/8
4 + 2 = 6
Flow is 600 gmp
What is the nozzle pressure of a solid stream nozzle on a handline? A solid stream nozzle on a master stream?
handline: 50 psi
master stream: 80 psi
Define Friction Loss
the pressure lost as water travels through hose, piping, couplings, and appliances
What are the 3 major factors that influence friction loss?
- the size of the hose
- the volume of water
- the length of the hose
What are the 2 factors that influence friction loss that are not accounted for and why?
- The condition of the hose : because you have no control over it
- Kinks in the hose: because you shouldn’t have any
What equation is used to find the Friction Loss per 100’ of handline?
[(gpm x n) /10] - 10
n= 3 for 1 3/4”
ex: 200 gmp through 100’ of 1 3/4’
[(200 x 3)/10] - 10
(600/10) - 10
60 - 10 = 50 psi FL per 100’
What equation is used to find the Friction Loss per 100’ of 4”?
Q x (Q - 1) /4
ex: 500 gpm through 100’ of 4”
Q = 5
[5 x (5 - 1)] /4
(5 x 4) /4
20 /4 = 5 psi FL per 100’
When accounting for appliance value in PDP equation, what is an appliance?
piece of equipment other than pumps, hose, and nozzles used in producing fire streams
What is the minimum intake pressure for any pump?
20 psi
How many psi do you add or subtract for elevation?
.5 psi per foot
5 psi per floor
Anytime 2 or more lines are pumped, what must be set?
Pressure Relief Valve
Handlines are NOT to be pumped over what at any time on the fireground?
250 psi
How should sprinklers be pumped? (4)
- use 2 1/2” hose
- Connect ALL inlets on building
- Pump 100 psi with nothing showing
- Increase to 150 psi if evidence of working or active fire
When pumping foam, what psi must you pump at?
200 psi
When pumping foam, what elevation can you NOT exceed?
30’
What is the MAXIMUM length of foam lines?
200’ of 1 3/4”
