Pump Manual - Principles of Friction Loss

Question 1

Principle #1: friction loss varies directly with the length of the hose or pipe

Answer 1

double the length of the hose = double the friction loss

pg 24

Question 2

Principle #2: When hoses are the same diameter, friction loss varies with the square of the increase in flow (gpm)

Answer 2

Double the flow = quadruple the friction loss

pg 24

Question 3

Principle #3: For same discharge, friction loss varies inversely as the fifth power of the diameter of the hose

Answer 3

The smaller the diameter, the greater the friction loss

Question 4

Principle #4: For a given velocity flow, friction loss is approx the same regardless of pressure on the water

Answer 4

Friction loss is caused by speed of water, not the pressure

Question 5

Parallel hose lines - effect on friction loss

Answer 5

Compared to a single line:

2 lines = 1/4 the FL
3 lines = 1/9 the FL
4 lines = 1/16 the FL

Question 6

Friction loss multipliers (M) by hose diameter

Answer 6

1"            --->   150
1 3/4"      --->   10
2 1/2"     --->    2
3"           --->    1
4"           --->    0.2  (divide by 5)
5"           --->    0.05 (divide by 20)

Question 7

Elevation pressure when distance above pump is known

Answer 7

EP = 0.434 x H

As a rule, add 5 psi for every 10 feet elevation above pump, reduce psi by 5 for every 10 ft drop below pump

Question 8

Calculating how high (elevation) water can be pumped with a given psi

Answer 8

H = 2.304 x P

Question 9

Appliance Friction Loss - standpipe

Answer 9

<350 GPM => 10 psi

>350 GPM => 25 psi

Question 10

Appliance Friction Loss - master stream (ladder pipes, deck guns, blitz fire)

Answer 10

25 PSI for all GPM

• by definition master stream is flowing >350

Question 11

Appliance friction loss for appliances (wyes, siamese, manifold)

Answer 11

<350 gpm => 0 psi

>350 gpm => 10 psi

Question 12

Appliance friction loss - foam eductor

Answer 12

50 psi