Chapter 7 - Theoretical Pressure Calculations

Question 1

Friction loss and elevation pressure loss (when applicable) are combined with the loss associated with appliances added to the layout to create ?

Answer 1

Total Pressure Loss (TPL)

p 210

Question 2

What is the formula for friction loss in the customary system?

Answer 2

FL = CQ²L
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

Question 3

• 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.

Answer 3

Appliance

p 213

Question 4

In order to conduct rapid elevation pressure loss calculations on the fireground, driver/operators may employ the following formula? (customary)

Answer 4

EP = 0.5H
EP = Elevation Pressure in pounds per square inch (psi)
0.5 = A constant 
H = Height in feet 

p 214

Question 5

In each hose layout, friction loss is affected by factors such as _______ ___________ and the _________ of the layout.

Answer 5

hose diameter / length

p 214

Question 6

When using more than one hoseline of equal length and equal diameter, friction loss calculations need only be made for?

Answer 6

one line

p 215

Question 7

When calculating pressure loss with a master stream device, the driver/operator must add _____ psi to the pressure loss calculation.

Answer 7

25 psi

p 217

Question 8

• 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.

Answer 8

Pump Discharge Pressure (PDP) / pump discharge pressure

p 218

Question 9

What is the formula used to calculate pump discharge pressure?

Answer 9

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

Question 10

Calculate and set the pump discharge pressure based on the hoseline with the ?

Answer 10

greatest pressure requirement

p 219

Question 11

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

Answer 11

• 50 psi
• 80 psi
• 100 psi
• 50 or 75 psi

p 219

Question 12

• 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.

Answer 12

Net Pump Discharge Pressure (NPDP)

p 219

Question 13

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 ____________.

Answer 13

friction loss / elevation

p 210

Question 14

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.

Answer 14

length and diameter / appliances

p 210

Question 15

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.

Answer 15

pressure / subtracting

p 211

Question 16

Fireground operations often require the use of ___________ such as reducers, gates, wyes, and manifolds.

Answer 16

appliances

p 213

Question 17

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.

Answer 17

25 psi

p 213

Question 18

In each hose layout, friction loss is affected by factors such as hose __________ and the _________ of the layout.

Answer 18

diameter / length

p 214

Question 19

_________ ____________ loss involves friction loss, loss or gain due to elevation, as well as appliance friction loss (when flow exceeds 350 gpm).

Answer 19

Total pressure

p 214

Question 20

Multiple Hoselines (Equal Length)

When diameters vary, calculations must be made for ?

Answer 20

each hoseline

p 215

Question 21

Wyed Hoselines (Equally Length)

Common fireground operations include a ____, ____, or ____ inch hoseline wyed into two or more smaller lines for fire attack.

Answer 21

2 1/2, 3, or 4 inch

p 215

Question 22

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 ?

Answer 22

1 1/2 to 2 1/2 inches / nozzle pressures

p 215

Question 23

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.

Answer 23

Siamese

p 216

Question 24

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.

Answer 24

25 percent less

p 216

Question 25

Many fire departments have ______________ pressures that a D/O is expected to supply to the fire department connection (FDC) in standpipe equipped occupancies.

Answer 25

predetermined p 216

Question 26

In order to determine the required pressure for a standpipe system, the _______ __________ loss must be calculated.

Answer 26

total pressure loss p 216

Question 27

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 ?

Answer 27

each hoseline supplied by separate discharges to individual nozzles p 216

Question 28

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.

Answer 28

highest p 216

Question 29

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.

Answer 29

highest p 217

Question 30

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.

Answer 30

gated / gating / endanger p 217

Question 31

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.

Answer 31

multiple / Siamese / large diameter p 217

Question 32

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.

Answer 32

bends / bends p 218

Question 33

The sum of the pressure loss encountered as well as the required nozzle pressure will be used to determine the ?

Answer 33

pump discharge pressure p 218

Question 34

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.

Answer 34

pump discharge pressure / discharge pressure p 219

Question 35

When supplying multiple hoselines, the D/O will need to compensate for specific pressure requirements of ?

Answer 35

individual lines p 219

Question 36

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 ?

Answer 36

net pump discharge pressure (NPDP) p 219

Question 37

In the case of a pumper being supplied by a hydrant or another pumper, the net pump discharge pressure is the difference between the ?

Answer 37

pump discharge pressure and the incoming pressure from the supply source. p 219

Question 38

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.

Answer 38

average p 237

Question 39

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.

Answer 39

length / number p 237