Friction Loss

Question 1

First principle

Answer 1

If all other conditions are the same friction loss varies directly with the length of hose or pipe.

The longer the hose the more friction loss it will have

P. 178

Question 2

Second principle

Answer 2

When hoses are the same size friction loss varies approximately with the square of the increase in the velocity.

Increasing the flow creates more friction loss in a hose or pipe.

Flow doubles increasing friction loss 4x

Flow triples increasing friction loss 9x

Question 3

Third principle

Answer 3

For the same discharge friction loss varies inversely as the fifth power of the diameter of the hose.

Using larger hose decreases friction loss.

3 inch hose to the 5th power is 243
4 inch hose to the 5th power is 1024
Divide them and you get 0.24
Take the decimal out and make it 24 and subtract my 100 and there is 76% reduction in friction loss in the larger 4 inch hose

P. 179

Question 4

Forth principle

Answer 4

For a given velocity friction loss is approximately the same regardless of the pressure on the water

P 179