CWS 102 Flashcards
How many gallons are in one cubic foot?
7.48 gallons
1 MGD is equal to how many cubic feet per second?
1.55 cfs
1 MG is equal to how many acre feet?
3.07 af
How much does a gallon of water weigh?
8.34 lbs
How many square feet are in 1 acre?
43,560 square feet.
1 cubic foot per second is equal to how many gallons per minute?
448.8 gpm
How many cubic feet are in one acre foot?
43,560 cubic feet
What do you multiply MGD by to get cfs?
1.55
How many gallons are in 1 acre foot?
325,851 gallons
How many minutes are there in 1 day?
1440 minutes
How many seconds are there in 1 day?
86,400 seconds
How is tank Rise and Fall calculated?
Tank rise (or fall) = Gallons (into or out of tank) / gallons per foot
How is Volume Change calculated in a Tank Rise/Fall equation?
Volume change = flow rate x time (= Q x t)
What is the gallons-per-foot equation in Tank Rise/Fall?
gallons per foot = 0.785 x D x D x 1’ x 7.48
How many gallons-per-foot are there in a tank with a 1-foot diameter? Not memorized. Use a calculator.
5.8718 gallons
What does GPCD mean?
Gallons Per Capita per Day
What are the units of GPCD?
gallons-per-day per person
How is GPCD determined?
Divide the average daily gallons used in a District’s service area by the population served
How do you calculate Water Loss?
Subtract the gallons measured at the meters from the total gallon-output in the system to get the total gallons lost. Then see what percentage the gallons lost is of the total water output. Gallons lost divided by total output, multiplied by 100.
What is Peak Demand Factor?
A ratio between the maximum water usage (peak demand) during a specific time period, compared to the average water usage.
What are the units of Peak Demand Factor?
It doesn’t have any because it’s a ratio.
What is the equation for Peak Demand Factor?
PDF = Peak/Average
How do you convert feet of head to psi?
Divide feet of head by 2.31
How do you calculate sidewall pressure?
Depth in feet multiplied by 62.4 pounds per cubic foot
How do you convert psi to feet of head?
Multiply psi by 2.31
How many feet of head are there on the side of a tank at a depth of 25 feet?
25 feet of head
How do you calculate specific gravity?
Density of a solid or liquid divided by the density of water.
What is the density of water?
62.4 pounds per cubic foot
What is the specific gravity of air?
0.075 pounds per cubic foot
How do you calculate pressure in pounds per square foot?
depth times 62.4 pounds per cubic foot
How do you calculate hydrostatic force?
Pressure times Area
1 horsepower is equal to how many ft-lbs/min?
33,000 ft-lbs/min
1 horsepower is equal to how many ft-lbs/s?
550 ft-lbs/s
How do you convert ft-lbs/min to horsepower?
Divide by 33,000
1 horsepower is equal to how many watts and kilowatts?
1HP = 746w and 0.746kW
How do you determine the percent strength of a solution by weight?
Weight of the solute divided by weight of the solution, multiplied by 100.
How do you determine weir overflow rate?
Weir flow (gpd) divided by Weir length (ft)
How do you determine Surface overflow rate?
Flow (gallons per day) divided by tank surface area (sqft)
How do you determine filter loading rate?
Flow (gpm) divided by filter surface area (sqft)
How do you convert gpm/sqft to inches of waterfall/minute?
Multiply by 1.6
The filter backwash rate is the same equation as what?
The filter loading rate
1 gpm/sqft is equal to how many inches per minute?
1.6 in/min
What is the minimum oxygen content for a confined space?
19.5%
Where in a chlorine storage facility should ventilation system intake be located?
Lowest point in the room typically 12 inches from the floor
What program/documents provide the employee with pertinent information of hazardous substances in the workplace?
SDS: Safety Data Sheet
What’s the nominal percentage of oxygen in a room?
20.9%
