Ch 7. Theoretical Pressure Calculations

Question 1

Why must driver/operators know the amount of friction loss and pressure lost in the fire hose?

Answer 1

To effectively provide water for fire streams

Question 2

What two characteristics of fire hose must be known to calculate friction loss?

Answer 2

Length and diameter

Question 3

The combination of friction loss, elevation pressure loss, and loss associated with appliances is referred to as:

Answer 3

Total pressure loss

Question 4

What are the two ways of determining friction loss?

Answer 4

Calculations in performing tests

Question 5

What is the formula for determining friction loss?

Answer 5

FL = C x Q2 x L

Question 6

When jurisdictions perform their own tests for friction loss coefficients, testing should be conducted using:

Answer 6

Actual hose that will be used during firefighting operations

Question 7

When determining friction loss coefficients, how many types of hose should departments test at one time:

Answer 7

Only one type of hose at a time

Question 8

When testing for friction loss coefficients, departments that use a Pitot tube should use what type of nozzle?

Answer 8

A smoothbore nozzle

Question 9

When testing friction loss coefficients, departments that use a flow meter should use what type of nozzle?

Answer 9

Any type of nozzle

Question 10

What is the assumed appliance loss when flowing less than 350 GPM?

Answer 10

0 psi

Question 11

What is the assumed appliance loss when flowing greater than 350 GPM?

Answer 11

10 psi

Question 12

What is the assumed appliance loss for all master stream appliances, regardless of the flow that will be used?

Answer 12

25 psi

Question 13

Why is it important to factor in friction loss for Handline nozzles?

Answer 13

It is a very significant factor in pressure loss and must be taken into account

Question 14

Elevation pressure is created by elevation differences between:

Answer 14

The nozzle and the pump

Question 15

The CUSTOMARY formula for elevation pressure loss is:

Answer 15

0.5 x height in feet

(.434 x height in feet for theoretical)

Question 16

The METRIC formula for elevation pressure loss is:

Answer 16

10 x height in meters

Question 17

The CUSTOMARY formula used to determine elevation pressure in a multistory building is:

Answer 17

5 PSI x (number of stories -1)

Question 18

The METRIC formula used to determine elevation pressure in a multistory building is:

Answer 18

35 Kpa x (number of stories -1)

Question 19

When determining friction loss in multiple hose lines of equal length and who’s diameters are the same, it is necessary to perform calculations for:

Answer 19

Only one line

Question 20

When the diameters of hose lines very, friction loss calculations must be made for each hose line, and then said based on the:

Answer 20

Higher pressure

Question 21

In order to avoid having two different nozzle pressures when using a wye, it is important that the two smaller attack lines wyed from the supply line are:

Answer 21

The same length and diameter

Question 22

Friction loss is approximately 25% less than that of a single hose line at the same nozzle pressure when:

Answer 22

Two hose lines of equal length are Siamese to supply a fire stream

Question 23

Jurisdictions are likely to have predetermined pressures when connecting to the FDC to supply a _______?

Answer 23

Standpipe

Question 24

When an incident may require the use of multiple hose lines of the same or different diameter that are of unequal length, friction loss must be calculated for:

Answer 24

Each hose line supplied by separate discharges to individual nozzles

Question 25

When using a manifold appliance and the hose lengths are unequal and/or the diameter is different, total pressure loss in the system is based on:

Answer 25

Highest pressure loss of any of the lines

Question 26

What is the appliance loss of a master stream device?

Answer 26

25 psi

Question 27

When calculating total pressure loss for elevated waterways, the driver operator must consider:

Answer 27

Pressure loss in the aerial device

Question 28

Pump discharge pressure equals the sum of what three factors?

Answer 28

Friction loss, nozzle pressure loss, elevation pressure loss

Question 29

What is the pump discharge pressure formula?

Answer 29

PDP = NP + FL + EL + AL

Or

PDP = NP + TPL

Question 30

Pump discharge pressure should be calculated and set based on:

Answer 30

The hose line with the greatest pressure requirement

Question 31

What is the safe and efficient nozzle pressure for a solid strong nozzle (handline)?

Answer 31

50 psi

Question 32

What is the safe and efficient nozzle pressure for a solid stream nozzle (master stream)

Answer 32

80 psi

Question 33

What is the safe and efficient nozzle pressure for a fog nozzle?

Answer 33

100 psi

(50 for Akron Assault)

Question 34

The formula for net pump discharge pressure is:

Answer 34

NPDP = PDP - Intake reading

Question 35

Friction loss is caused by a number of factors including the condition of the hose and couplings as well as any kinks in the hose line. However, what is the primary consideration in determining friction loss?

Answer 35

The primary consideration is the volume of water flowing per minute.

Question 36

What is the only truly accurate method for determining pressure loss in a particular hose lay?

Answer 36

The only truly accurate method involves measuring the pressure at both ends of the hose line and subtract in the difference