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 OWDP Home > Course Offerings> Basic Hydraulics Pre-Test


This test is a tool to help you decide if you should attend the morning session of the Alternative Sessions course. This material will be covered for those that are unfamiliar with this information.

Instructions
You may figure these out in your head, on a scratch pad or with a calculator. Accuracy
is not the issue. Consult a text book if your want. Select the closest answer.

Conversions
7.5 gallons = 1 cubic ft
1 ft "head" = 2.3 psi

Questions 1 - 3

10 gallons per minute (gpm) is flowing through a 2 inch pipe from left to right as shown
in the sketch below. The pipe size is reduced to 1 inch for a second section.

Picture for problems 1, 2 and 3
Question 1

The velocity of the water in the 1 inch pipe is:

 A) the same as in the 2 inch pipe
B) twice as fast as in the 2 inch pipe
C) four times as fast as in the 2 inch pipe
D) can't be determined from given data
Question 2

Approximately how long would it take this flow of water to fill a 1000 gallon tank?

A) 10 minutes
B) almost 2 hours
C) all day
Question 3

Approximately how long would it take this flow of water to fill a tank which was 8 feet long, 5 feet wide and 5 feet deep? (inside dimensions)

A) 20 minutes
B) about 1 hour
C) about 3 hours
D) half a day


Questions 4 and 5
Picture for problems 4 and 5
Question 4

To measure the pressure in the 2 inch line several different clear plastic devices were attached to the line in turn at the same place. What one of the following is true about the level to which the water would rise in the various devices?

A) Water would rise highest in the thinnest pipe
B) The tapered devise would show the lowest elevation
C) The "S" shaped devise would not fill beyond the first bend
D) The wide pipe would not rise as much as the thin pipe
E) None of the above
Question 5

If the pressure at "A" is about 1 psi., about how high would water rise in the device which rises the most?

A) approximately 2 inches
B) approximately 2 feet
C) squirt out the top
D) no rise at all


Question 6

The concept of frictional head loss in pipes is important for determining the correct pump for a system. If a given flow of water produced 40 feet of head loss in a given section of 1 inch pipe, about how much head loss would be experienced if the pipe diameter where changed to 2 inch?

A) 80 feet
B) 40 feet
C) 20 feet
D) 10 feet
E) 1 foot
Question 7

Consider a level pipe with a constant diameter flowing at 10 gpm under pressure. Frictional head loss will cause which one of the following to occur?

A) less water will come out of the end
B) the water will come out slower
C) the "head" will decrease toward the end
D) the pressure will increase toward the end
E) none of the above


Questions 8 and 9
Picture for problems 8 and 9
Question 8

Consider a tilted pipe with a constant diameter flowing at 10 gpm under pressure from A to B. What can be said about the pressure at B relative to the pressure at A?

A) the pressure at B must be higher than the pressure at A
B) the pressure at B must be less than the pressure at A
C) the pressure at B must be equal to the pressure at A
D) there is not enough information to make a determination
Question 9

Consider a tilted pipe with a constant diameter flowing at 10 gpm under pressure from B to A. What can be said about the pressure at B relative to the pressure at A

A) the pressure at B must be higher than the pressure at A
B) the pressure at B must be less than the pressure at A
C) the pressure at B must be equal to the pressure at A
D) there is not enough information to make a determination


Questions 10 and 11
Picture for problems 10 and 11

Question 10

Consider a level pipe with a constant diameter flowing at 10 gpm under pressure. The change of diameter will cause which one of the following to occur if the water is flowing from left to right?
(You may ignore the "minor terms or losses" which are caused by turbulence at the junction.)

A) the pressure at B must be higher than the pressure at A
B) the pressure at B must be less than the pressure at A
C) the pressure at B must be equal to the pressure at A
D) there is not enough information to make a determination
Question 11

Consider a level pipe with a constant diameter flowing at 10 gpm under pressure. The change of diameter will cause which one of the following to occur if the water is flowing from right to left?
(You may ignore the "minor terms or losses" which are caused by turbulence at the junction.)

A) the pressure at B must be higher than the pressure at A
B) the pressure at B must be less than the pressure at A
C) the pressure at B must be equal to the pressure at A
D) there is not enough information to make a determination


Question 12
Picture for problem 12

Consider a berm around an E-T bed or sand filter. As the distance across the ET bed or sand filter increases, the size of the minimum acceptable berm must:

A) increase to withstand the additional forces from the sand and water.
B) need not change its dimension
C) can actually decrease because the bottom is getting bigger
D) not enough information to make a determination