Plumbing math

Atmospheric pressure at sea level is almost _____.

• 8.43

• 434

• 14.7

• 62.4

One cubic foot contains _____ cubic inches.

• 231

• 144

• 1728

• 61.2

The volume of water in one cubic foot is approximately _____.

• 7.5 gallons

• 10 quarts

• 28 quarts

• 6.5 gallons

The pressure at the base of a column of water 1-inch high is approximately _____. 

• 2.31 psi

• .434 psi

• 4.335

• .036 psi

Answer explanation

1 gal of water weighs 8.34 lbs

There is 7.48 gallons in 1 cubic foot

If you multiply those, you get 62.38 lbs/ft³

We need to figure out pounds per square inch (psi). There are 12 inches in a foot so to get to that multiply 12 x 12 x 12 and you get 144

To turn 62.38 sq/ft³ into pounds per square FOOT you take 62.38 ÷ 144 to get .433 pounds per foot

Then divide .433 by 12 (since there are 12 inches in a foot) to get pounds per inch (psi)

Then you just take .433 ÷ 12 inches to turn it from 1 ft to 1 inch.

.433 ÷ 12 = .036 psi

The pressure required to raise a column of water 200 feet would be (neglect friction losses) _____ psi.

• 200

• 43

• 86

• 100

Answer explanation

P=.433xH

The full length of a house sewer is 100 feet and the total fall is 25 inches. The slope of the sewer is  approximately _____ inch/foot

• 1/2”

• 1/4”

• 3/8”

• 1/8”

Answer explanation

Slope=total fall/ length of sewer or run

One cubic foot of water weighs approximately _____ pounds.

• 43.4

• 231

• 144

• 62.4

A temperature of 212 degrees Fahrenheit is equivalent to _____ Celsius.  

• 273

• 212

• 100

• 180

Answer explanation

C= 5/9 (F-32)

One square foot contains approximately _____ square inches.

• 144

• 100

• 48

• 36

Answer explanation

12x12

The scale on a set of plans states that 1/8 inch = 1 foot. The actual length of a waterline with plan  dimensions of 5 inches would be approximately _____ feet.

• 64

• 8

• 40

• 5

Answer explanation

1 inch = 1 foot divided by 1/8 = 8 feet per inch

8 feet x 5” = 40 feet