Volume 43 Number 2
ANSI/NSF Standard Revisions Improve Real World Application
The ANSI/NSF drinking water treatment unit (DWTU) standards are living documents that change as market and certification needs mature and develop. NSF International has published four standards that have had significant revisions to address changes in regulatory requirements, improvements in test methods and clearer literature requirements. Some of the changes are common throughout the standards, but each standard has changes unique to the products they cover.
Conditions on conditioners
The only difference between the two standards is the material safety requirements under ANSI/NSF Standard 44 that require formulation information and a link to extraction test data ensuring materials are safe for drinking water. This link to extraction test data can be provided to system manufacturers by the component manufacturers who test their components for material safety under ANSI/NSF Standard 44. The key components of a softener -- where certification for material safety may be easily transferred to system manufacturers -- are valve head assemblies and bypass valves. Component certification of tanks, ion exchange resin and distribution components may allow a system manufacturer to completely eliminate extraction testing. If material safety cannot be completely satisfied with component certification, frequently one test will qualify a large family of softeners.
As states have begun to require softeners to demonstrate efficient operation, the requirements under ANSI/NSF Standard 44 have changed allowing softeners to have both efficiency and non-efficiency rated salt settings. The previous version of Standard 44 required that an efficiency rated softener couldn't have salt settings above the maximum that was qualified as efficient. That requirement has been removed from the standard, and improved customer information has been included. The required customer information includes that, when an efficiency rating was claimed, the salt setting, resultant capacity and standard are stated. When a softener capacity is claimed, the salt setting required for that capacity is also stated. The intent of the DWTU Joint Committee was to minimize confusion and educate consumers so they could operate a softener at the efficiency setting desired.
Aesthetics, health and RO
Each of the standards has also changed the requirements of the Performance Data Sheet (PDS). The PDS is designed to inform the purchaser of the details of certification with information on testing and use limitations. The previous versions of the standards required the PDS to contain a summary of test results. This caused problems when products were re-tested and slight changes in reduction percentages occurred, so system manufacturers had to take the costly step of printing new literature. The 2000a versions of the standards require the PDS to contain the minimum requirements of the standard and, if a manufacturer wishes, they may include the actual data and percent reductions obtained in testing.
Additions -- Seventeen substances have been added to this table to expand the number of possible claims for chemical reduction to 50. These substances and their test parameters are listed in Table 1. Many of these substances were available as claims under the volatile organic compound (VOC) surrogate test program that qualifies 47 substances as a group. This inclusion here allows these substances to be claimed individually.
Changes -- Nine substances previously in the table had influent and/or maximum effluent concentrations changed. Changes to influent values were due to occurrence data becoming available, or the effluent value was changed and the influent was set at three times the maximum effluent value. Effluent values were changed to harmonized values agreed upon by both the U.S. Environmental Protection Agency and Health Canada. A summary of the nine, updated substances are shown in Table 2.
Re-testing -- Three substances that will require re-testing of all certified claims are o-dichlorobenzene, lindane and 2,4,5-TP (Silvex). The changes that occurred in these substances cannot be qualified by testing based on previous requirements. Several of the substances had changes that could be qualified by previous testing if test results don't exceed the new, lower maximum effluent values. These substances include 2,4-D, fluoride, lead and methoxychlor. The changes to chromium will not require re-testing since all certified customers prior to this standard's version had to claim both types of chromium and were tested in combination.
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