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Here are seven rules of thumb that can keep your purchase of a replacement refrigerator from becoming a continuing drain on your pocketbook:
1) Don't buy a refrigerator bigger than you need. One rule is to choose a model that has 10 cubic feet of food storage for a family of two and then add an extra cubic foot for each additional person in the household. The freezer should be 40 to 45 percent as large as the food storage section. Thus a family of 4 will want to pick a model that is between16.5 and 17.5 cubic feet, and a family of 6 might choose a model that is about 20 cubic feet.
2) Side-by-side refrigerator/freezers use more energy than units with the freezer above or below the fresh food compartment. Side-by-sides also take up more space for the same storage volume.
3) Through-the-door features, like cold water or automatic ice dispensers, impose as much as a 20 percent penalty in increased electricity usage as compared to similar models without these extras.
4) Manual defrost models use less energy than automatic defrost units, consuming as much as one-third less. However, you should defrost the freezer when 1/4 inch of frost has accumulated.
5) Two refrigerators use more electricity than a single large refrigerator with equivalent storage space. And it is never a good idea to keep a half empty "his" refrigerator in the garage with beer and soda, while a "hers" refrigerator is in the kitchen with room to spare.
6) Don't let an old, inefficient refrigerator pass onto the used appliance market - recycle it for parts only. If your old refrigerator earns a negative investment return for you, it won't reward a family that must pay $50 or $80 on top of the hefty energy bills.
7)) Look for the Energy Star label. It is a quick and easy way to avoid paying for a mistake with each month's electricity bill.
You can convert pipe size to gallons per minute of flow by calculating the cross-sectional area of the pipe and making some reasonable assumptions about pipe volume and the rate of flow. Pipe sizing is measured by the internal diameter of the pipe, not the overall outside diameter. Once determined, the overall volume can be calculated. Pipe flow is described in gallons per minute. Shorter lengths of pipe will have a greater flow than a longer length of the same diameter. This is caused by internal resistance of the pipe itself. By the same reasoning a larger diameter pipe will have a greater flow or GPM than a smaller pipe at the same pressure or flow rate. Pressure is described as pounds per square inch. The square-inch measurement is determined by the area of the pipe. The pounds are the amount of force that is placed on the liquid to push it through the enclosed space.With that background, you can estimate the flow based on the pipe size.
Find the cross-section area of the pipe. Area is equal to pi times the radius squared or a = 3.14 x r2. A two-inch diameter pipe would have a cross-section area of 3.14 x 12 or 3.14 square inches.
Understand that water has a certain pressure associated with the height of that water. One pound of water pressure, or 1 PSI, is equal to 2.31 feet of elevation in height. In other words, a 1-inch column or pipe of water that is 2.31 feet high will have a pressure of 1 PSI. The overall height -- not volume -- of the pipe corresponds to the pressure. A 6-inch diameter pipe that is 2.31 feet high will only have 1 PSI.
Find the volume of the 2-inch diameter pipe in Step 1 that has a length of 10 feet. Ten feet is equal to 120 inches. Multiply 3.14 square inches, the cross sectional area, times the length. The volume of the pipe is equal to 376.8 cubic inches of volume.
Convert cubic inches into cubic feet. One cubic foot equals 1,728 cubic inches. Divide 376.8 cubic inches by 1,728 cubic inches per cubic foot and the answer is .218 cubic feet. This means that the 2-inch diameter pipe that is 10 feet long has an internal volume of .218 cubic feet.
Calculate the amount of water that can be contained in the section of pipe at any given time. One cubic foot of water is equal to 7.48 gallons. Multiply 7.48 gallons by .218 cubic feet and the amount of water in the pipe is equal to 1.63 gallons.
Find the GPM if the flow of water is one foot per second. Multiply the one-foot per second flow by 60 seconds per minute and the flow is now 60 feet per minute. In other words the water will flow through the 10-foot pipe six full volumes for every minute. Since the piping contains 1.63 gallons per 10 feet of pipe, multiply 1.63 by six and the final GPM is equal to 9.78 GPM of water flow from the 2-inch diameter pipe.
Since a cubic foot is 12" x 12" x 12", if you were to make the sand 12" thick you would have 375 cubic feet of sand. However, since you want your sand 2" thick (which is 1/6th of a foot), you simply divide the 375 by 6 to get the value of sand in cubic feet (62.5).
Calculating the cubic feet of a space requires multiplying the area of the bottom times the average height. You get the bottom area by multiplying the length times the width. Remember, to get cubic feet, you need all your measurements in feet to start with.
Here is your formula:
VOLUME (in cubic feet) = Length (in feet) X Width (in feet) X Height (in feet)
If it's a rectangular room you're working with, it is all straightforward. If there are irregular walls, it may be necessary to divide up the room into rectangular sections and then add together their individual volumes. If the ceiling is sloped, you need to use the height that has the same ceiling area above it as below it. Good luck! Truly.
Multiply 21 inches by 14 inches by 10 inches to get 2940 cubic inches. There are 12 inches in a foot, so there are 12^3=1728 cubic inches in a cubic foot. Divide 2940 cubic inches by 1728 cubic inches per cubic foot to get about 1.7 cubic feet.
Alternatively, first convert all measurements to feet. 21 inches is 1 3/4 feet, 14 inches is 1 1/6 feet, 10 inches is 5/6 feet. Multiply them together to get 245/144 cubic feet, which again is about 1.7 cubic feet.
It's always nice when doing a problem two different ways gives the same answer.
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