Page 173 - Facility Piping Systems Handbook for Industrial, Commercial, and Healthcare Facilities

WATER TREATMENT AND PURIFICATION

WATER TREATMENT AND PURIFICATION 4.9

TABLE 4.3 Resistivity and Conductivity Conversion
*
Grains/gal ppm ppm Conductivity, Resistivity,
as CaCO 3 as CaCO 3 NaCl μmho/cm MΩ/cm
99.3 1,700 2,000 3,860 0.00026
74.5 1,275 1,500 2,930 0.00034
49.6 850 1,000 1,990 0.00050
24.8 425 500 1,020 0.00099
9.93 170 200 415 0.0024
7.45 127.5 150 315 0.0032
4.96 85.0 100 210 0.0048
2.48 42.5 50 105 0.0095
0.992 17.0 20 42.7 0.023
0.742 12.7 15 32.1 0.031
0.496 8.5 10 21.4 0.047
0.248 4.25 5.0 10.8 0.093
0.099 1.70 2.0 4.35 0.23
0.074 1.27 1.5 3.28 0.30
0.048 0.85 1.00 2.21 0.45
0.025 0.42 0.50 1.13 0.88
0.0099 0.17 0.20 0.49 2.05
0.0076 0.13 0.15 0.38 2.65
0.0050 0.085 0.10 0.27 3.70
0.0025 0.042 0.05 0.16 6.15
0.00099 0.017 0.02 0.098 10.2
0.00070 0.012 0.015 0.087 11.5
0.00047 0.008 0.010 0.076 13.1
0.00023 0.004 0.005 0.066 15.2
0.00012 0.002 0.002 0.059 16.9
0.00006 0.001 0.001 0.057 17.6
none none none 0.055 18.3
†
* Grains per gal = 17.1 ppm (CaCO 3 ).
† Theoretical maximum.

are given in Table 4.3. Specific conductance in actual practice is normally measured by
probes suspended in the stream of water.

Total Suspended Solids
This figure is the sum of all of the suspended material found in a water sample and is commonly
measured in either parts per million (ppm, w/w), or milligrams per liter (mg/L). For all practical
purposes, these two forms of measurement are equal to each other (1 ppm = 1 mg/L).
Turbidity in water is classified by the size of the particulates in micrometers (1/1000
of an inch) and tested by a light interference method, known as nephelometric. This test
compares the color of the water sample to a standard color scale, which indicates the total
suspended solids based on this comparison. The most common reporting method is the
nephelometric turbidity unit (NTU). The higher the number, the more turbid the water.
The NTU measures the color of a beam of light passed through a water sample.
A common standard for potable water is the Standard Method for the Examination of Water
and Wastewater by the American Public Health Service, which uses formazin as the standard
for producing a known volume of turbidity. The standard color scale to which it is compared
is derived from the platinum cobalt unit (PCU). Other methods used less frequently are the

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