This invention relates to water purification systems. More particularly, this invention relates to water purification systems incorporating a method for the exposure of water to ultraviolet light.
It is known to use ultraviolet (UV) radiation to disinfect drinking water. It is also known that ultraviolet radiation is a means for meeting the bacteriological requirements of the drinking water standards as enumerated in the Safe Drinking Water Act (SDWA), 42 U.S.C. §300(f) et seq. (1974). Studies have indicated that ultraviolet radiation at a level of 2,537 Angstrom units applied at a minimum dosage of 16,000 micro-watt-seconds per square centimeter at all points throughout a water disinfecting chamber is adequate to purify water for drinking. It is generally known to use 30,000 micro-watt seconds per square centimeter to obtain the desired effect. Using a higher standard helps account for any losses that may occur in the exposure chamber. If a UV lamp is used that maintains 80% power over 9,000 hours (approximately one year), then setting a standard of 38,000 micro-watt-seconds per square centimeter would insure that the lamp would require replacement no more than yearly, while adequately sterilizing the water flow that is exposed to the UV lamp.
In commonly configured ultraviolet light water purification systems, ultraviolet light serves the purpose of exposing a fluid to ultraviolet light radiation which either kills bacteria or renders bacteria unable to reproduce. A straight quartz fluid tube permits an ultraviolet light source to be inserted in the inside diameter of the tubing while water is passed over the outside diameter of the length of the lamp.
One commonly known means of exposing water to ultraviolet light is to place a light source in a straight quartz tube with water flowing through an outer chamber past the linear distance of the ultraviolet light source. Such a design generally requires a pressure cylinder to be built around the lamp-supporting construction. This also requires that the pressurized cylinder be at the same length or longer than the provided ultraviolet light source. It would, therefore, be advantageous to develop an apparatus that can more easily be used to purify water.