Geoscience Reference
In-Depth Information
TABLE 14.1
Water Properties (Temperature, Specific Weight, Density)
Temperature
(°F)
Specific Weight
(lb/ft
3
)
Density
(slugs/ft
3
)
Temperature
(°F)
Specific Weight
(lb/ft
3
)
Density
(slugs/ft
3
)
32
62.4
1.94
130
61.5
1.91
40
62.4
1.94
140
61.4
1.91
50
62.4
1.94
150
61.2
1.90
60
62.4
1.94
160
61.0
1.90
70
62.3
1.94
170
60.8
1.89
80
62.2
1.93
180
60.6
1.88
90
62.1
1.93
190
60.4
1.88
100
62.0
1.93
200
60.1
1.87
110
61.9
1.92
210
59.8
1.86
120
61.7
1.92
Source:
Spellman, F.R.,
Handbook of Water and Wastewater Treatment Plant Operations
, 3rd ed., Lewis
Publishers, Boca Raton, FL, 2013.
Environmental practitioners must also learn the laws of chemistry and to use them, as they
must. But they must know even more. Environmental practitioners must know the ramifications of
chemistry when it is out of control. Chemistry properly used can perform miracles. Out of control,
chemicals and their effects can be devastating. In fact, many of the current environmental regula-
tions dealing with chemical safety and emergency response for chemical spills resulted because of
catastrophic events involving chemicals.
14.1.1 d
ensity
and
s
peCiFiC
g
ravity
When we say that iron is heavier than aluminum, we are saying that iron has a greater density than
aluminum. In practice, what we are really saying is that a given volume of iron is heavier than the
same volume of aluminum. Density (
p
) is the mass (weight) per unit volume
of a substance at a
particular temperature, though it generally varies with temperature. The weight may be expressed
in terms of pounds, ounces, grams, kilograms, etc. The volume may be liters, milliliters, gallons,
cubic feet, etc. Table 14.1 shows the relationship between temperature, specific weight and density
of fresh water.
Suppose we had a tub of lard and a large box of crackers, each having a mass of 600 grams. The
density of the crackers would be much less than the density of the lard because the crackers occupy
a much larger volume than the lard occupies. The density of an object can be calculated by using
the following formula:
Mass
Volume
Density
=
(14.1)
In water/wastewater operations, perhaps the most common measures of density are pounds per
cubic foot (lb/ft
3
) and pounds per gallon (lb/gal):
• 1 cubic foot (ft
3
) of water weighs 62.4 lb, so its density is 62.4 lb/ft
3
.
• 1 gallon of water weighs 8.34 lb, so its density is 8.34 lb/gal.
Search WWH ::
Custom Search