Gallon , conversion units

The first practical conversion units came with the advent of the steamship and its requirement of fresh water for boilers. Today, most of the large ocean-going vessels have their battery of evaporators. The Forrestal class carriers of the United States Navy, for example, carry four 50,000-gallon-per-day evaporators to supply the water needs of those huge ships and their large crews. 

Increasing population and industrial requirements have made it necessary in some parts of the world to recover fresh water from sea water. The total world production of fresh water from sea water today, produced mostly by distillation processes, amounts to more than 25,000,000 gallons per day. A rather rapid increase in water production is anticipated. For example, Israel plans to integrate its coastal power plants with sea water conversion units in order to produce 50 billion gallons of water per year to supplement its natural water resources (11). 

For the conversion of gallons to litres it has been assumed that in Colombia the United States gallon is used, with 3.785 litres to the gallon, and in Myanmar the imperial gallon, with 4.546 litres to the gallon. 

Figure 6. Proposed 35,000 gallon-per-day sea water conversion pilot plant unit...

For some readers (especially Americans), the metric system (other wise known as the SI system) is vague, or somewhat unfamiliar. 99% of all the units of weight and measurement in this book are given using the SI system therefore, a translation from one unit to another may be needed for some to fully interpret the quantities. As most people are probably aware however, most laboratory equipment is automatically calibrated in SI units, so even inexperienced persons will not have to worry too much about knowing the SI system. Regardless, try a few conversions of your own just for practice. Example Convert 150 Celsius into Fahrenheit—Solution multiply 150 by 1.8 and then add 32. The answer would be 302 Fahrenheit. Example 2 Convert 1.2 gallons into milliliters—Solution multiply 1.2 by 3,785. The answer would be 4542 milliliters. 

A car s rate of fuel consumption is often measured in miles per gallon (mpg). Determine the conversion factor between miles per gallon and the SI unit of meters per cubic decimeter (1 gallon = 3.785 dm, and 1 mile = 1609.344 m). Express 30.0 mpg in SI units. 

Again, the SI conversions are more uniform and easier to remember. The older system is even more confusing than it appears here when you consider the fact that English cups, pints, ounces, and quarts are different than the U.S. units with the same names. For example, there are 1.2 U.S. gallons in 1.0 English gallon For this reason alone, American students can probably see the need for a common system. 

The conversion factor, 4 qt/1 gal, serves as a bridge, or linkage, between the unit that was given (gallons) and the unit that was sought (quarts). 

Different processes will be developed having advantages for particular applications. For example, some types of processes will be more economical for treating brackish waters some processes are expected to be particularly adaptable to use in household-type units or small installations others will be best for multimillion gallons per day plants. Factors connected with location, such as fuel costs, weather conditions, and waste disposal conditions, can determine which of several conversion processes would be the most economical to use. 

The grooves on the outside surface of the copper tube, which had a height of 0.026 to 0.040 inch and a pitch of 0.04 to 0.06 inch, evidently promoted dropwise condensation, since in some tests the steam-film coefficient was estimated to be as high as 10,000 in the usual units. The power requirement for the wiper was estimated to be 1/4 hp. for an 8000-gallon-per-day still, so that the cost of the power is negligible. The total energy requirement will depend mainly on the power to compress the steam and this would be no different than for any other vapor-compression process. This statement was made because a recent news report claims that this evaporator requires only one fourth as much energy as other conversion systems. 

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