The A. O. Smith Carbon Block Cartridge ONE Filter is a point-of-entry cartridge tank filter built around an 8-inch by 40-inch vessel with an In/Out Head and a bypass valve. It is designed to take the place of several smaller cartridge housings: the single large-capacity cartridge extends the interval between changes and handles higher flow rates than a conventional housing. The system may be used as primary filtration, or as pre-filtration or post-filtration within a larger treatment train, and it can be run as a single-tank system.
The tank is supplied pre-assembled and the cartridge ships separately for installation on site. Carbon block cartridges are available in three grades: a 3 micron and a 20 micron for particulate, taste, and odor reduction, a 3 micron chloramine reduction grade, and a 0.5 micron grade for lead, PFOA/PFOS, and cyst reduction. A. O. Smith rates the carbon block series at flow rates up to 28 gpm at a 3 psi pressure drop. The same tank also accepts the pleated, string wound, meltblown, and NanoAl cartridge series, so the filtration grade can be matched to the water being treated.
Both the inlet and the outlet are at the top of the tank on 1-inch NPT connections, which simplifies the plumbing run. Cartridge access is from the top through a patented snap-ring retainer and requires no special tools. A 1-inch NPT socket at the base of the tank accepts an optional drain, which allows the cartridge to be rinsed periodically and lets accumulated particles flush out of the vessel; A. O. Smith recommends installing it. Each cartridge carries a stand-off leg at its base so debris can clear the filter and settle where the drain can remove it. The system requires no electrical connection.
The 0.5 micron carbon block cartridge carries certified contaminant reduction claims, but only as part of a fully assembled contaminant reduction system rather than as a property of this tank on its own. That configuration is designated CW-840-PB and requires the CT-05-CB-AMCYL-IO cartridge installed in this tank together with a qualifying softener or backwashing filter equipped with a metering service alarm. Installed that way, it is certified by IAPMO R&T according to NSF/ANSI 53 for lead and cyst reduction and NSF P473 for PFOA/PFOS reduction, over 100,000 gallons. Without the qualifying metered unit, the same cartridge is certified to 50,000 gallons. The tank must not be used on water that is microbiologically unsafe or of unknown quality without adequate disinfection before or after the system.
