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 During our recent NSF testing, Neptune-Benson's Defender filter achieved the best turbidity removal test results ever! To pass the NSF turbidity testing criteria, a filter must reduce the "test" turbidity level by 70% within 5 turnovers. The Defender reached the acceptable level in one turnover. In addition, by the third turnover, the Defender reduced the "test" turbidity level by 100%! At the fourth and fifth turnovers, the Defender reduced the initial turbidity level, actually improving the quality of the city water source. The current NSF testing guideline for precoat filters includes certification up to 2.0 gpm/ft2 (4.89 m3/hr) and the Defender easily passed the entire series of tests.
Based on our experience, Neptune-Benson recommends a more conservative flow rate range than the max NSF listing. This lower range has proven to enhance particle removal, extend filter cycles and improve operational efficiency.
The design premise and the selection process of a precoat filter is no different than a sand filter. While our sand filters are NSF listed up to 20 gpm/ft2 (48.9 m3/hr), optimal filter performance is achieved when flow rates are limited to 70-75% of NSF listed rate.
While the Defender's max flow rate is NSF listed at 2.0 gpm/ft2 (4.89 m3/hr), Neptune-Benson's recommended flow rate range remains 0.5-1.4 gpm/ft2 (1.22-3.42 m3/hr).
A newly expanded Defender technical sheet has been issued. This technical sheet now includes a "Recommended Flow Rate Range" column to make model selection easier.
Download technical sheet here
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