# Certification Action Line – April 2015

April 1, 2015

1. What is the relationship between the radius and the diameter?

a. the radius is the length of the boundary of a circle, the diameter is the width of a circle

b. the radius is the amount of space enclosed by a circle, the diameter is the width of a circle

c. the diameter is equal to the radius squared

d. the diameter is equal to two times the radius

2. Which of the following is defined as a volume of fluid that passes over a specific surface area in a given unit of time?

a. flow rate

b. flow speed

c. flux

d. velocity

3. Square feet of filter media surface area in a cylindrical tank (square feet in a round tank) can be obtained by the formula:

a. length times width

b. 3.1416 (π) times diameter squared

c. 3.1416 (π) times radius squared

d. area of the base times height

4. It is desired to filter eight gallons per minute (gpm) through two parallel depth filters at a maximum loading of 10 gpm per square foot of surface area. What is the minimum diameter of the two filter tanks (each filter will assume one-half the eight gpm flow)?

5. What backwash flow rate is required in gpm to backwash a nine-inch diameter filter if the desired backwash flux is 18 gpm per square foot?

6. Assuming no short circuiting through six feet of water flow in a 30-inch diameter retention tank, what is the detention time when the flow rate is eight gpm?

7. How much of a gallon of sodium hypochlorite is required to dose a well at 100 milligrams of chlorine per liter of water in the well? The casing diameter is six inches and the length of the water-filled casing is 80 feet. Sodium hypochlorite is 5.25 percent or 52,500 milligrams of chlorine per liter.

8. A submersible well pump delivers 30 gpm against typical operating heads. If the desired chlorine dose is five milligrams per liter, what should be the chlorine feed rate in pounds per day?

9. Estimate the desired strength (as a percent of chlorine) of a hypochlorite solution being pumped by a hypochlorinator that delivers 10 gallons per day. The water being treated requires a chlorine feed rate of 1.8 pounds of chlorine per day.

10. How many gallons of water must be added to one gallon of a 5.25 percent hypochlorite solution to produce a 2.16 percent hypochlorite solution?

11. Estimate the gallons of hypochlorite solution pumped by a hypochlorinator if the hypochlorite solution is in a container with a diameter of 18 inches, and the hypochlorite level drops five inches during a specified time period.

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