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OCR for page 51
51
Name: SODIUM POLYPHOSPHATE, GLASSY
CAS No.: 10124-56-8
Chemical Formula:
Description:
(NaPO3)n Na2O
Na2O/P2O5 = 1.1 to 1.3
P2O5 = 63-68%
NAS/CWTC 024-82
Typically, n = 14
Colorless, odorless, glassy solid, plates, granules, or
powder. Slight salty taste. Hygroscopic and extremely
soluble in water.
Use:
Used as metal corrosion inhibitor and sequestrant to avoid
iron, copper and manganese discoloration. Threshold scale
inhibitor and water softener.
Purit Reauirements
Y ~ .
Analyses of available grades of glassy sodium polyphos-
phate show the presence of cadmium and lead but at levels
far below that which would necessitate RMIC values based
on a maximum dosage of 10.7 mg/liter. If analyses are
desired, the following protocol is recommended.
Bulk Sample Collection:
Sample in accordance with Standard for Sodium Tripolyphos-
phate, AWWA B503-78, American Water Works Association,
Denver, Colorado (1978).
OCR for page 52
52
Analytical Sample Preparation
.
Weigh out 2.5 g of sodium polyphosphate. In a 150-ml
acid-washed beaker dissolve the sample in 100 ml of
deionized distilled water. Under a hood, acidify the
solution with concentrated HNO3 to a pH of less than
2. Gently heat the solution to reduce the volume below
100 ml, making certain that it does not boil. Quantita-
tively transfer to a 100-ml acid-washed volumetric flask
and make to volume with deionized distilled water.
Process a reagent blank by the same procedure.
Sample Analyses:
The analyses are to be performed on the sodium polyphos-
phate solution in accordance with:
Standard Methods for the Examination of Water and Waste-
water, 15th Edition, American Public Health Association,
Washington, D.C. (1981).
Cadmium
Lead
Section 304
Section 304
Representative terms from entire chapter:
distilled water
