# Onsite Arithmetic: Pump Math Part 1 — Answers

### Interested in Systems/ATUs?

Systems/ATUs

Here are the answers to today’s practice problem.

1. If there is a rectangular pump tank with dimensions of 4 feet wide by 7 feet long, what are the gallons per inch in the tank?
Answer: Determine this by taking the area x 1 feet of depth x 7.5 gallons/cubic foot ÷ 12 inches/foot = gallons per inch.

4 feet x 7 feet x 1 foot = 28 cubic feet

28 cubic feet x 7.5 gallons/cubic foot = 210 gallons ÷ 12inches/ foot = 17.5 gallons/inch

2. What if the pump tank is circular and has a diameter of 5 feet? What are the gallons per inch in this circular tank?
Answer: Determine the area and then determine the gallons per inch the same as for the rectangular tank.

Area of a circle = so area is 3.14 x 2.5 feet x 2.5 feet = 19.6 square feet x 1 foot = 19.6 cubic feet

19.6 cubic feet x 7.5 gallons/cubic foot = 147 gallons ÷ 12 inches/foot = 12.25 gallons per inch

3. If in both tanks the pump height plus the blocks underneath the pump equals 18 inches, how many gallons does it take to cover the pump?
Answer: For the rectangular tank: 18 inches x 17.5 gallons/inch = 315 gallons

For the circular tank it takes: 18 inches x 12.25 gallons/inch = 220 gallons

4. If the pump needs to deliver a total of 150 gallons, (assuming there is a check valve) how many inches are between the on and off floats to deliver the dose?
Answer: For the rectangular tank: 150 gallons ÷ 17.5 gallons/inch = 8.5 inches between floats

For the circular tank: 150 gallons ÷ 12.25 gallons/inch = 12 inches between floats

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