Ch.8 Theoretical Pressure Calculations

Question 1

What is the primary determinant of friction loss?

What are some other factors as well?

Answer 1

The volume of water flowing per minute

Hose condition, coupling condition, kinks

Question 2

What makes up total pressure loss? TPL

Answer 2

Friction loss and elevation pressure

Question 3

Name the equation for computing friction loss.

Answer 3

FL=CQ^2L

FL= friction loss
C=constant
Q= flow rate in hundreds of gpm (flow/100)
L= hose length in hundreds of feet (length/100)

Question 4

Name the following coefficients for these size lines:

1”
1 3/4”
2 1/2”

Answer 4

1” is 150
1 3/4” is 15.5
2 1/2” is 2

Question 5

The book considers appliance friction loss to be insignificant in cases where friction loss is less than ?

Answer 5

350 gpm

Question 6

The book assumes ____ pressure loss for flows less than 350 gpm and ____ pressure loss for each appliance (other than master stream devices) in a hose assembly flowing 350 gpm or more

Answer 6

0 psi pressure loss

10 psi pressure loss

Question 7

This book assumes a friction loss of ____ in all master stream appliances, regardless of the flow

Answer 7

25 psi

Question 8

Water exerts how much psi per foot of elevation?

Answer 8

0.434 psi

Question 9

Name the elevation pressure equations

Answer 9

EP=.5H

EP= elevation pressure in psi
.5=constant
H= height on feet

   Or, for stories....

EP=5psi * (number of stories - 1)

Question 10

When 2 hose lengths are Siamesed together, it has approximately ___ percent of friction loss as a single hose line at the same pressure.

What about if three lines are siamesed?

Answer 10

25 percent as much friction loss as the single line

10 percent as much of you use 3 lines

Question 11

Do Siamesed lines supplying an attack line have a different set of coefficients for the friction loss equation?

Answer 11

Yes