In recent years, the scope of NSF/ANSI 50 was expanded to include swimming pool treatment chemicals in addition to equipment used in recreational water treatment and filtration. Reference information about NSF/ANSI 50 evaluation criteria for pool treatment chemicals is given on pages 10-11 of the NSF Recreational Water Products Bulletin at http://www.nsf.org/newsroom/recreational-water-products-bulletin.
Under the new language, pool chemicals are evaluated for health effects based on oral, dermal and inhalation routes of exposure. Several pool chemical categories now fall within the scope of NSF/ANSI 50, including clarifiers, disinfectants and filtration aids. Click here to view all of the NSF/ANSI 50 pool chemicals listings.
The chemical product categories now found in NSF/ANSI 50 include pool salt, which is certified for use with electrolytic salt water chlorine generators. To date, two companies (Compass Minerals America, Inc. and Compass Minerals Canada Corp.) have been certified by NSF to standard 50 for pool salt products.
Under NSF/ANSI 50, salt products are evaluated to health effects criteria and receive testing for trace impurities, including regulated metals and radionuclide (gross alpha/beta) content. For electrolytic chlorinators, which produce chlorine from salt, NSF/ANSI 50 specifies performance criteria including specifications for design pressure, chemical production rate, chemical resistance and a life test.
In the salt water chlorination process for swimming pools, a chlorine generator uses electrolysis in the presence of dissolved salt to produce sodium hypochlorite, which is a disinfecting agent in the pool water. This process utilizes salt as a feed stock to produce chlorine on site, as opposed to a traditional pool chlorination system where the pool water is treated with chlorine (or a chlorine-containing compound) through direct addition. There are two major categories of on-site chlorine generators used in swimming pools:
• Brine (batch) type electrolytic chlorine generators, which produce brine prior to pool addition (from salt and a plumbed-in water source) and then electrolyze the brine to produce chlorine for pool water disinfection.
• In-line electrolytic chlorinators, which are installed in the pool’s circulation system to produce chlorine from available salt in the recirculated water.