Hydraulics

Question 1

What happens when there is excessive pressure at the heads?

Answer 1

Misting or fogging

Question 2

If the GPM are doubled, the PSI:

Answer 2

quadruples

Question 3

Hydraulics is:

Answer 3

the science of dynamic and static water

Question 4

What is the weight of one gallon of water?

Answer 4

8.3 pounds

Question 5

62.4 pounds represents the weight of

Answer 5

a cubic foot of water

Question 6

What does PSI stand for

Answer 6

pounds per square inch

Question 7

How many feet of water (in height) does it take to equal 1 PSI

Answer 7

2.31

Question 8

One foot high of water will create

Answer 8

.433 PSI

Question 9

How many feet of head are needed to produce 65 PSI: 65÷.433 =

Answer 9

150.1 feet of head

Question 10

If you have 167 feet of head, what is the PSI? 167 X .433 =

Answer 10

72.3 feet of head

Question 11

There is a 70 foot water tower on a hill that is 150 feet high. The water pressure at a home, being serviced by this water tower, is 70 PSI. What is the feet of head difference between the home and the base of the hill?
let y = water tower plus hill height
70÷.433 = x
y-x = _____ feet of head

Answer 11

58.3 feet of head

Question 12

An elevation gain in the piping will yield

Answer 12

loss in PSI

Question 13

An elevation loss in the piping will yield

Answer 13

an increase in PSI

Question 14

What is the maximum acceptable velocity of water in pvc piping?

Answer 14

5 fps

Question 15

What is the maximum acceptable velocity of water in copper piping?

Answer 15

9 fps

Question 16

What is the pressure loss for 141’ of 1” Type K copper pipe flowing 12 gpm?
1.41 x 4.94 =

Answer 16

6.97 psi

Question 17

What size Class 200 pvc pipe would be adequate if flowing 38 gpm?
refer to chart

Answer 17

2”

Question 18

If your pipe is flowing 34 gpm, what size pipe should be used?

Answer 18

Class 200 1½”

Question 19

How much pressure has been gained from point A to point D, due to an elevation difference?
height of water above point A (150’) - height of water above point D (220’) = x
x * .433 = y

Answer 19

y = 30.31 PSI gain

Question 20

What is not considered in selecting the most taxed zone to work the hydraulics?

Answer 20

Lowest elevation

Question 21

Which one of these is a rule to follow when working hydraulics?
a) Take the most direct route from the point in question back to the city main or point in question
b) Take the most direct route from the point in question back to the main line or point in question
c) Pick up the GPM at intersections, but don’t calculate the friction losses on any of the pipe running to those sprinkler heads.
d) A&C

Answer 21

Both A&C

Question 22

A separate calculation is needed if :
a) the type of pipe is different
b) The GPM are different
c) The size of the pipe is different
d) All of the above

Answer 22

D) All of the above

Question 23

In exercise #49, what would the design pressure be if the static pressure was 70 instead of 60?

Answer 23

The same (Remember the definition for design pressure: Minimum head pressure plus total pressure loss. Therefore, the static pressure does not affect the calculation of design pressure)