Page 118 - Water Engineering Hydraulics, Distribution and Treatment

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Chapter 4
Water requirements of selected industries
Table 4.9
(95 Lpcd); of wayside restaurants, 10 gpcd (38 Lpcd) on a
Unit of
patronage basis; and of work or construction camps, 45 gpcd
Industry
Gal per unit
production
(170 Lpcd). Resort hotels need about 100 gpcd (380 Lpcd),
Food products
and rural hospitals and the like, nearly twice this amount.
a
Beet sugar
7,000
Ton of beets
Farm animals have the following approximate require-
Proof gal
125–170
Beverage alcohol
ments: dairy cows, 20 gpcd (75 Lpcd); horses, mules, and
b
Meat
600–3,500
1,000 lb live
steers, 12 gpcd (45 Lpcd); hogs, 4 gpcd (15 Lpcd); sheep, 2
weight
gpcd (8 Lpcd); turkeys, 0.07 gpcd (0.26 Lpcd); and chick-
Case
Vegetables, canned
3–250
ens, 0.04 gpcd (0.15 Lpcd). Cleansing and cooling water
Manufactured products
add about 15 gpcd (57 Lpcd) for cows to the water bud-
Vehicle
Automobiles
10,000
get of dairies. Greenhouses may use as much as 70 gpd per
1,000 lb
Cotton goods Quantities of Water Demand 20,000–100,000 rural factories (exclusive of manufacturing uses) are 25 gpcd
2
−3
3
2
1,000 ft (2.856 × 10
m ∕d∕m ) and garden crops about
2
Leather 1,000 ft of 200–64,000 half this amount.
hide
Paper ton 2,000–100,000 Military requirements vary from an absolute minimum
Paper pulp ton 4,000–60,000 of 0.5 gpcd (1.9 Lpcd) for troops in combat through 2–5
gpcd (7.6–19 Lpcd) for soldiers on the march or in bivouac,
Mineral products
and 15 gpcd (57 Lpcd) for temporary camps, up to 50 gpcd
Aluminum (electrolytic ton 56,000 (max)
(190 Lpcd) or more for permanent military installations.
smelting)
Copper
Smelting ton 10,000 c 4.4 VARIATIONS OR PATTERNS OF WATER
Refining ton 4,000 DEMAND
Fabricating ton 200–1,000
Petroleum Barrel of 800–3000 d A pattern is a function relating water use to time of day. Pat-
crude oil terns allow the user to apply automatic time-variable changes
Steel ton 1,500–50,000 within the system. Most patterns are based on a multiplication
factor versus time relationship, whereby a multiplication fac-
Conversion factors: 1 gal = 3.785 L; 1 ton = 2000 lb = 0.9072 metric ton;
3
2
2
3
1lb = 0.4536 kg; 1 ft = 0.0929 m ; 1 barrel = 5.615 ft = 0.159 m = tor of 1.0 represents the base value (often the average value,
42 gal. Q avg ). This relationship is written as Q = kQ avg , where Q =
t
t
a Includes 2,600 gal (9,841 L) of flume water and 2,000 gal (7,570 L) of demand at time t and k = multiplier for time.
barometric condenser water. Water consumption changes with the seasons, the days
b Lower values for slaughterhouses; higher for slaughtering and packing.
c Total, including recycled water; water consumed is 1,400 gal (5,390 L). of the week, and the hours of the day. Fluctuations are greater
d Total, including recycled water; water consumed is 30–60 gal (113.55– in small rather than large communities and during short rather
227.1 L). than long periods of time. Variations are usually expressed as
ratios to the average demand. Estimates for the United States
public or private utilities for less than 10% of their needs. are as follows:
Food processors, by contrast, purchase about half of their
water from public supplies, largely because the bacterial Ratio of rates, k Normal range Average
quality of drinking water makes it de facto acceptable.
About 90% of the industrial draft is taken from surface Maximum day: average day (1.5–3.5):1 2.0:1
Maximum hour: average day (2.0–7.0):1 4.5:1
sources. Groundwaters may be called into use in the summer
because their temperature is then seasonally low. They may
be prized, too, for their clarity and their freedom from color, Where existing water quantity data are not available to
odor, and taste. accurately determine the instantaneous peak demand for the
Available sources may be drawn on selectively: munic- design year, the following criteria may be used as a minimum
ipal water for drinking, sanitary purposes, and delicate pro- for estimating the instantaneous peak demand:
cesses, for example; and river water for rugged processes For 220 people or less: Q ins peak = 9(Q avg day )
and cooling and for emergency uses such as fire protec-
/ 0.167
tion. Treatment costs as well as economic benefits are the For more than 220 people: Q ins peak = 7(Q avg day ) P k
determinants.
where
4.3.4 Rural Water Consumption Q ins peak = instantaneous peak water demand (gpm or
L/min)
The minimum use of piped water in rural dwellings is about
Q = average daily water demand (gpm or L/min)
20 gpcd (75 Lpcd); the average about 50 gpcd (190 Lpcd). avg day
Approximate drafts of rural schools, overnight camps, and P = design year population (thousands)
k