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Irrigation > Hydraulics > Flashcards

Hydraulics Flashcards

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1
Q

What happens when there is excessive pressure at the heads?

A

Misting or fogging

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2
Q

If the GPM are doubled, the PSI:

A

quadruples

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3
Q

Hydraulics is:

A

the science of dynamic and static water

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4
Q

What is the weight of one gallon of water?

A

8.3 pounds

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5
Q

62.4 pounds represents the weight of

A

a cubic foot of water

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6
Q

What does PSI stand for

A

pounds per square inch

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7
Q

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

A

2.31

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8
Q

One foot high of water will create

A

.433 PSI

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9
Q

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

A

150.1 feet of head

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10
Q

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

A

72.3 feet of head

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11
Q

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

A

58.3 feet of head

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12
Q

An elevation gain in the piping will yield

A

loss in PSI

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13
Q

An elevation loss in the piping will yield

A

an increase in PSI

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14
Q

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

A

5 fps

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15
Q

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

A

9 fps

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16
Q

What is the water velocity of 1” Class 200 pvc pipe flowing 12 gpm?

A

3.46 fps (refer to chart)

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17
Q

What is the water velocity of 1½” Class 200 pvc pipe flowing 16 gpm?

A

4.83 fps (refer to chart)

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18
Q

What is the pressure loss for 80’ of 1” Class 200 pvc pipe flowing 16gpm?
.80 x 3.11 =
the 3.11 comes from the class 200 chart

A

2.49 psi

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19
Q

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

A

6.97 psi

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20
Q

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

A

2”

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21
Q

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

A

Class 200 1½”

22
Q

What is the static pressure at point E?
200’ x .433 =

A

86.6 psi

23
Q

What is the dynamic water pressure at point A?
1) first get static water at point A:
150’ x .433 = 64.95 PSI
2) Subtract friction loss in the 125’:
*1½” class 200 flowing 34 GPM gives you 2.20 PSI loss per 100’
*1.25 x 2.20 = 2.75 PSI from the class 200 chart loss in the 125’ of pipe
*Now subtract this figure from your static pressure: 64.95 - 2.75 =

A

62.2 psi

24
Q

What is the dynamic water pressure at point D?
220’ elevation of water tower over point D x .433 = x
4.5 pip footage x 2.20 = y
x/y = pressure at point D

A

85.4 psi

25
Q

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

A

y = 30.31 PSI gain

26
Q

How much pressure has been lost, from elevation difference, from point D to point E?
20’ difference going uphill
20’ x .433 =

A

8.7 psi

27
Q

What is the static water pressure at point D?
220 x .433 =

A

95.3 psi

28
Q

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

A

Lowest elevation

29
Q

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

A

Both A&C

30
Q

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

A

D) All of the above

31
Q

What is the GPM flowing through lateral line G when zone valve #2 is operating?

A

0 GPM

32
Q

Calculate the GPM flowing in lateral piping section G when zone #1 is operating?

A

24 GPM

33
Q

What is the GPM flowing through lateral line A when zone valve #2 is operating?

A

4 GPM

34
Q

What is the GPM flowing through back flow device if zone valves #1 and #2 were operating at the same time?

A

48 GPM

35
Q

What size should lateral pipe section G be sized?

A

1 ¼”

36
Q

What size should lateral pipe B be sized?

A

¾”

37
Q

What size should lateral pipe C be sized?

A

1”

38
Q

What size should the main line be at the PVB, if zones #1 and #2 were running at the same time?

A

2”

39
Q

What is the pressure loss in zone valve #1 when it is running?

A

4.7

40
Q

What is the pressure loss in the PVB when zone valve #2 is operating?

A

5 PSI

41
Q

What is the pressure loss in the main line when zone valve #2 is operating?
.55’ x 2.12 (from the chart) =

A

1.17 PSI

42
Q

What is the pressure loss in the meter when zone valve #1 is operating?

A

3.4 PSI

43
Q

What is the friction loss from the outlet side of the zone valve #2 (when running) to the PVB?

A

5.87 PSI

44
Q

What is the total friction loss from the supply side of the meter to valve #1 when it is operating?

A

10.06 PSI

45
Q

When zone valve #2 is operating, what is the total pressure loss from head A to the PVB back flow device?

A

7.66 PSI

46
Q

Calculate the static pressure at zone valve #2 with zone valve #1 operating?

A

49.17 PSI

47
Q

If the GPM are based on a 6 GPM full head and the main line section that is 30’, is 47’ instead, what is the static pressure at zone valve #1 with zone #2 operating

A

51.56 PSI

48
Q

What is the design pressure and actual head pressure of head B when zone valve #11 is operating?

A

47.28 & 42.72

49
Q

What is the design pressure at Head A when zone valve #5 is operating?

A

31.60

50
Q

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

A

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)

51
Q

What is the design pressure and actual head pressure of Head C when zone valves #9 and #11 are operating at the same time. Assume there is an elevation gain of 13 feet at Head C, the main line is 1½”, the PVB is 1½”, the water meter is 1”, and the copper service is 1½”

A

54.68 & 35.32

52
Q

In exercise #51, if the minimum head pressure was 25 instead of 20 PSI, what would the actual head pressure be?

A

The same (remember, the definition for actual head pressure: static pressure minus total pressure losses. Therefore, the minimum head pressure does not affect the calculation of actual head pressure)

Irrigation (2 decks)

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