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THE SILVER INSTITUTE LETTER
VOLUME V, NUMBER 5, MAY, 1975
SILVER GUARDS GOOD HEALTH
Silver is the key element in many machines and materials that restore and maintain good health for millions of people. The paragraphs below report new developments in the field.
News From The Pure Water Front: Men in space will soon get drinking water purified by nine grams of silver bromide in a cylinder less than 20 centimeters (8 inches) long, weighing about 1.3 kilograms (2.75 pounds). Compared to earlier prototypes, the new unit weighs 90% less, needs only one-third the space, doubles the production of pure water, and simplifies the process from a three-step to a single-step procedure; it obviates the need for mixing, metering and testing water while in flight, and eliminates the risk of corrosion. Several things happened last year to make the dramatic advance possible:
- New research shows that 100 parts per billion (ppb) of silver will safely provide pure drinking water to crews of future space vehicles. This is more than the 50 ppb recommended by the U.S. Public Health Service many years ago although, also for many years, Swiss and German health officials have authorized 200 and 100 ppb of silver, respectively, for the purification of drinking water. So the Johnson Space Center, U.S. National Aeronautics and Space Administration (NASA) has set 100 ppb of silver as the water potability standard for space flights.
- Use of 100 ppb of silver ions eliminates the need for the 1,000 to 1,500 ppb of chlorine generally used to purify drinking water.
- Also news: it is found that earlier silver purifiers used unnecessarily high concentrations of silver. The NASA Preliminary Prototype sent water over silver chloride spheres that put 1,000 ppb of silver ions into the water; then, the silver was removed by ion exchange resin; finally, 50 ppb were reintroduced to maintain purity. The heavy, first dosage purified "worst case" water coming from the vehicle's fuel cells to supplement other water supplies. But the recent news is that 1,000 ppb was more than enough.
- Another recent development: The Space Shuttle's fuel cells have been greatly improved so that supplemental water coming from them is cleaner than was previously the case.
The Advance Prototype Silver Ion Water Bactericide System, to give it its full name, is made by Chemtric, Inc., 9330 West Williams Street, Rosemont, Illinois 60018. The result of years of research, testing and perfecting, the unit is designed for use in Space Shuttles being built by Rockwell International's Space Division in Downey, California.
The new Chemtric design calls for a single canister containing a cartridge to filter out particulates, and a column of silver bromide granules and activated charcoal. Fuel cell water enters the unit at an inlet port and is distributed by a manifold into the housing; it flows radially through a filter that excludes particulates and bacteria; then it moves axially through the silver bromide-activated charcoal column where it is dosed with 80 ppb of silver ions, with minor variations in the dosage occurring, depending on the temperature of the water and its rate of flow. The activated charcoal particles separate the silver bromide granules and prevent their re-aggregation; the charcoal also adsorbs small quantities of organics. The process kills Pseudomonas aeruginosa and Type IIIa micro-organisms that are encountered in the water, as well as other bacteria.
For more information on health hazards such as chlorine and other drinking water contaminants please read through our "Health Topics" pages or review many of the information sites listed on our research page.
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