Factors, Formulas, Measurements

Question 1

How many cubic inches in a cubic ft?

Answer 1

1728 cu in

Question 2

How many cubic inches in a gallon?

Answer 2

231 cu in.

Question 3

How many lbs per cu ft of water?

Answer 3

62.5 lbs

Question 4

1 foot of water depth equals ____ psi.

Answer 4

.434 psi

Question 5

1 psi will raise water _____ft.

Answer 5

2.304 ft.

Question 6

Back pressure per story?

Answer 6

5 lbs psi per story

Question 7

Atmospheric pressure at sea level?

Answer 7

14.7 psig

Question 8

For each 1,000 ft rise in elevation, atmospheric pressure decreases _______ psi.

Answer 8

0.5 psi

Question 9

30” of Hg (Mercury) in depth = ________ psi

Answer 9

14.7 psi (atmospheric pressure)

Question 10

What is theoretical maximum lift?

Answer 10

33. 9 feet - not obtainable by a class A pumper

2. 304 ft * 14.7 psi (with a perfect vacuum)

Question 11

1” of Hg (Mercury) = _____psi.

Answer 11

.491 psi.

Question 12

1 psi = ________ “ Hg

Answer 12

2.04” Hg

Question 13

Mercury = _______ times heavier than water.

Answer 13

13.5 times heavier.

Question 14

1” Hg = _____ of water in depth

Answer 14

1” of Hg = 1.1 ft of water in depth.

Actual is 1.13 ft.

Question 15

What is the formula for GPM from an orifice?

Answer 15

30*(D^2)(✔️NP)

(Thirty times diameter squared times the square root of nozzle pressure)
Multiply answer by coefficient to get hydrant GPM.

Question 16

Coefficients for hydrants:
___ for rounded butt
___ for squared butt
___ for protruding butt

Answer 16

0. 9 rounded
1. 8 squared
2. 7 protruding

Question 17

Formula for smooth bore nozzle reaction.

Answer 17

1. 5(D^D)NP

1. 5 times diameter squared times nozzle pressure.

Question 18

Formula for fog nozzle reaction.

Answer 18

1/2GPM

Question 19

Formula for sprinkler discharge

Answer 19

1/2P+15

Question 20

Formula for Volume of a cylinder

Answer 20

Pi * R-squared * length

Question 21

Volume of a cylinder in gallons.

Answer 21

Pi * radius squared * length * 7.5

Convert cylinder into square feet before multiplying by 7.5.

Question 22

Formula for volume of a hose in gallons.

Answer 22

.0408 * D^D * length in feet.

Question 23

Friction loss coefficient for 2.5” hose

Answer 23

2 * Qsquared

Question 24

Friction loss coefficient for 1.75” hose

Answer 24

12 * Qsquared

Question 25

Friction loss coefficient for 1.5” hose

Answer 25

26 * Qsquared

Question 26

Friction loss coefficient for 1” hose

Answer 26

200 * Qsquared

Question 27

Friction loss coefficient for 3” hose

Answer 27

0.8 * Qsquared

Question 28

Friction loss coefficient for 4” hose.

Answer 28

0.2 * Qsquared

Question 29

Friction loss coefficient for parallel 2.”5 & 3” of equal lengths only.

Answer 29

1/3 * Qsquared

Use total GPM

Question 30

Pump capacity:
_______@150 psi
_______@200 psi
_______@250 psi

Answer 30

100% @ 150 psi
70% @ 200 psi
50% @ 250 psi

Question 31

What is the AFFF solution application rates for polar solvent and hydrocarbon fires?

Answer 31

0.1 GPM per Sq Ft. Of surface area

Question 32

Fog nozzle pressure

Answer 32

100 psi

Question 33

Handline smooth bore pressure

Answer 33

50 psi

1 1/8” tip and smaller.

Question 34

Heavy appliance smooth bore

Answer 34

80 psi

1 1/4” tip and larger

Question 35

Monitor friction loss

Answer 35

15 psi loss

Question 36

Wye/Siamese friction loss

Answer 36

10 psi loss

Question 37

Standpipe friction loss

Answer 37

25 psi loss

Question 38

Additional water available formula:

AKA “Like lines” rule

Answer 38

(Static psi - residual psi)/static psi = % drop

0%-10% = 3x additional flow

10%-15% = 2x additional flow

15%-25% = 1x additional flow.

Question 39

How many gallons in a cubic ft?

Answer 39

7.5 gallons

Question 40

Size and GPM for 2-1/2” smoothbore “playpipe” nozzle

Answer 40

Size.          Pressure
                 50psi.            80psi. 
1”             210 GPM        266 GPM 
1-1/8”      266 GPM       336 GPM 
1-1/4”      328 GPM        415 GPM

*Taken from GPM’s printed on nozzle