HYDROFLUOROSILICIC ACID SOL.

Use In Public Water Treating Plants

• The reduction in dental caries by adjusting the fluoride content of public water supplies is a matter of common knowledge today. half a century following the first installllllllllllllation in Grand Rapids. Michigan. Approximately 170 million people in over three thousand communities are now drinking fluoride - treated water from water purification plants where fluoridation is currently practiced. Fluoridation is concerned with the controlled introduction to water of the fluoride ion.
• Other materials in the fluoride compound simultaneously introduced into the water with the fluoride ions are carriers which provide no benefits and are non - toxic. The addition of one part per million of fluoride requires that the product be soluble. of definite concentration and have high purity standards. In conformity with the American Water Works Association standard B703 - 94. the term fluorosilicic acid has replaced the more technical designation of hydrofluosilicic acid. After the original work with sodium fluoride proved the effectiveness of fluoride on tooth health and a broad fluoridation program was envisaged. new sources of fluoride and economics of their use were investigated. Fluorosilicic acid is a high purity source of fluoride. It is simpler to use than any other chemical approved for water fluoridation purposes. primarily because it is a liquid and can therefore be accurately measured and fed with a minimum of equipment. In contrast to powdered or granular chemicals. it presents no dust problems. no measuring problems and handling requires a minimum of labor. Today most of the large cities and many small ones are fluoridating with fluorosilicic acid. It is readily available in tank cars or tank trucks and can also be supplied in 15 - gallon carboys and 55 - gallon drums. The addition of fluorosilicic acid to a water supply can be readily controlled to give a total fluoride (F) level of one part per million which has been established as effective for reducing tooth decay. It should be used in accordance with procedures approved by each state’s department of health.

Installllllllation

• In a typical large plant installation. rubber - lined vented storage tanks are usually mounted outside the building with the tanks ranging in size from 4.500 to 6.500 - gallon capacities. These tanks. equipped with recording level gages. feed the acid through plastic piping or tubing to the dosage unit. Feeding is regulated by controlled volume pumps. Metering is used for accurate flow records.
• Fluorosilicic acid may be handled in rubber - lined. saran or other available corrosive - resistant equipment as suggested below:
• Pipes and lines - - rubber. saran or polyethylene
• Pumps - - Lucite. saran or Hastelloy
• Valves - - rubber - lined or polyethylene - lined
• Tanks - - rubber - lined. saran or polyethylene - lined
• Acid should be pumped by positive diaphragm proportioning pumps.

Operation Procedure

The drum or drums of fluorosilicic acid should be mounted on a platform of sufficient size and capacity to permit weighing the amount used each day. Proportioning pumps deliver an accurate volume. but for small pumping rates. the dosage may be more satisfactorily regulated by periodic weighing of the drum. Whenever a drum of fluorosilicic acid is replaced on the scale. the time and weight should be recorded in the daily operating log. Whenever dosage is changed to a varying pumpage. the time and feeder setting should be recorded in the daily log.

• Tank truck. rubber of plastic - lined: 40.000 lbs (approx.)
• Tank car. rubber or plastic - lined: 196.000 lbs net (approx..)