Chapter 7 - Theoretical Pressure Calculations Flashcards
Friction loss and elevation pressure loss (when applicable) are combined with the loss associated with appliances added to the layout to create ?
Total Pressure Loss (TPL)
p 210
What is the formula for friction loss in the customary system?
FL = CQ^2L FL = Friction Loss in pounds per square inch (psi) C = Friction loss coefficient Q = Flow rate in hundreds of gallons per minute (gpm) (gpm/100) L = Hose length in hundreds of feet (feet/100)
p 212
- Generic term applied to any nozzle, wye, Siamese, deluge monitor, or other piece of hardware used in conjunction with fire hose for the purpose of delivering water.
Appliance
p 213
In order to conduct rapid elevation pressure loss calculations on the fireground, driver/operators may employ the following formula? (customary)
EP = 0.5H EP = Elevation Pressure in pounds per square inch (psi) 0.5 = A constant H = Height in feet
p 214
In each hose layout, friction loss is affected by factors such as _______ ___________ and the _________ of the layout.
hose diameter / length
p 214
When using more than one hoseline of equal length and equal diameter, friction loss calculations need only be made for?
one line
p 215
When calculating pressure loss with a master stream device, the driver/operator must add _____ psi to the pressure loss calculation.
25 psi
p 217
- Actual pressure of the water as it leaves the pump and enters the hoseline; total amount of pressure being discharged by a pump. In mathematical terms, it is the pump intake pressure plus the net _______ ____________ ____________. Measured in pounds per square inch or kilopasclas.
Pump Discharge Pressure (PDP) / pump discharge pressure
p 218
What is the formula used to calculate pump discharge pressure?
PDP = NP + TPL PDP = Pump Discharge Pressure in pounds per square inch NP = Nozzle Pressure in pounds per square inch TPL = Total Pressure Loss in pounds per square inch
p 218
Calculate and set the pump discharge pressure based on the hoseline with the ?
greatest pressure requirement
p 219
The following are safe and efficient nozzle pressures for common fire streams:
- Solid stream nozzle (handline) = _____ psi
- Solid stream nozzle (master stream) = _____ psi
- Fog nozzle = ______ psi
- Low pressure fog nozzle = ______ or ______ psi
- 50 psi
- 80 psi
- 100 psi
- 50 or 75 psi
p 219
- Actual amount of pressure being produced by the pump; difference between the intake pressure and discharge pressure. Also known as Engine Pressure or Net Pressure.
Net Pump Discharge Pressure (NPDP)
p 219
In order to effectively provide water for fire streams, it is necessary to know the amount of __________ _______ in the fire hose and the pressure loss or gain due to ____________.
friction loss / elevation
p 210
When making a friction loss calculation, the D/O must also account for the ________ and ___________ of the hose as well as ______________ that may be in use with the hoseline.
length and diameter / appliances
p 210
The only truly accurate method for determining pressure loss in a particular hose lay involves measuring the ____________ at both ends of the hoseline and _____________ the difference.
pressure / subtracting
p 211
Fireground operations often require the use of ___________ such as reducers, gates, wyes, and manifolds.
appliances
p 213
Appliance Pressure Loss (APL)
Friction loss in appliances varies with the rated capacity of the device as well as flow. Generally, a loss of ____ psi or greater is assumed when flowing the rated capacity.
25 psi
p 213
In each hose layout, friction loss is affected by factors such as hose __________ and the _________ of the layout.
diameter / length
p 214
_________ ____________ loss involves friction loss, loss or gain due to elevation, as well as appliance friction loss (when flow exceeds 350 gpm).
Total pressure
p 214
Multiple Hoselines (Equal Length)
When diameters vary, calculations must be made for ?
each hoseline
p 215
Wyed Hoselines (Equally Length)
Common fireground operations include a ____, ____, or ____ inch hoseline wyed into two or more smaller lines for fire attack.
2 1/2, 3, or 4 inch
p 215
Wyed Hoselines (Equal Length)
The attack lines generally range from _____ to _____ inches in diameter. These attack lines must be the same length and diameter to avoid having two different ?
1 1/2 to 2 1/2 inches / nozzle pressures
p 215
To accommodate larger volumes of water and keep friction loss rates reasonable, two or more parallel hoselines may be laid. These lines may be brought together with a ___________ at a point close to the fire.
Siamese
p 216
When two hoselines of equal length are siamesed to supply a fire stream, friction loss is approximately ____ percent less than that of a single hoseline at the same nozzle pressure.
25 percent less
p 216
Many fire departments have ______________ pressures that a D/O is expected to supply to the fire department connection (FDC) in standpipe equipped occupancies.
predetermined
p 216
In order to determine the required pressure for a standpipe system, the _______ __________ loss must be calculated.
total pressure loss
p 216
Occasionally, an incident may require the use of multiple hoselines of the same or different diameter that are of unequal length. When presented with scenario, the D/O must calculate the friction loss for ?
each hoseline supplied by separate discharges to individual nozzles
p 216
Multiple Hoselines (Unequal Length)
The hose line with the _________ friction loss represents the total pressure loss at the pump, assuming there is minimal change in elevation.
highest
p 216
Wyed Hoselines (Unequal Length) and Manifold Lines
When hose lengths are unequal and/or the diameter is different, the total pressure loss in the system is based on the __________ pressure loss in any of the lines.
highest
p 217
Hoselines requiring less than maximum pressure may be _______ down by the D/O. However, unless each manifold discharge is equipped with a pressure gauge, _______ down hoselines is based on guesswork and may ___________ attack crews working on that line.
gated / gating / endanger
p 217
Although master streams evolved from the same basic principles as other fire streams, they require a greater volume of water and are generally supplied by __________ hoselines with a __________ or a _______ __________ hose.
multiple / Siamese / large diameter
p 217
In an aerial device, the water must navigate several ______ in the aerial piping. It is these ______ that cause pressure loss due to the turbulence that is created as the water forcefully makes its way through the piping.
bends / bends
p 218
The sum of the pressure loss encountered as well as the required nozzle pressure will be used to determine the ?
pump discharge pressure
p 218
In some fireground situations, attack lines must be supplied with water before the D/O has time to calculate the correct ______ ___________ __________. Some jurisdictions calculate the __________ __________ for their pre connected attack lines in advance.
pump discharge pressure / discharge pressure
p 219
When supplying multiple hoselines, the D/O will need to compensate for specific pressure requirements of ?
individual lines
p 219
When required to discharge a specific pressure, fire apparatus pumps take advantage of the water pressure coming into the pumps water supply and add the required pressure to achieve ?
net pump discharge pressure (NPDP)
p 219
In the case of a pumper being supplied by a hydrant or another pumper, the net pump discharge pressure is the difference between the ?
pump discharge pressure and the incoming pressure from the supply source.
p 219
Total Pressure Loss Calculations - Master Streams
If unequal length or diameter of hose is used to supply a master stream, use the _________ of the hose lengths to simplify calculations.
average
p 237
Total Pressure Loss Calculations - Master Streams
In order to obtain the average, a D/O may add the _______ of each hoseline and then divide by the __________ of hoselines being used.
length / number
p 237
