Hyper-Filtration for Nitrox Preparation
With the widespread popularity of Nitrox diving, numerous dive shops are mixing air with pure oxygen to produce saleable "enriched air" mixtures. For safe blending, compressed air of purity greater than normal Grade E must be used. Known as "Oxygen Compatible Air" or OCA, this gas is permitted to have no more than 0.1 mg / M3 of hydrocarbon contaminants, whereas Grade E scuba air can contain 50 times that amount (5 mg / M3). Some dive shops are able to produce OCA with their regular processing systems if the compressor, lubricant, moisture separators and filters all function absolutely flawlessly. Many other air systems cannot achieve air of this purity under any circumstances. To routinely obtain OCA, most shops reprocess their Grade E air by passing it through an addition special filter known as a Hyper-Filter, which are described below .
These special hi-tensile aluminum towers will accept ONLY specific Hyper-Filter cartridges which actually "recirculate" the gas through high-purity chemicals that remove even trace level hydrocarbons. These super-filtration systems also control the pressure and flow rate at which the gas moves through the chemicals, thereby assuring complete removal of finite contaminants. Each Hyper-Filter System consists of the tower(s) with filter cartridge(s) plus pressure-controlling priority regulator, flow governor, gauge and check valves, all mounted on an aluminum base plate. Double and single tower systems are available. This apparatus not only produces OCA, but also serves as a safety backup in case of an unforeseen compressor / filter failure which releases dangerously high levels of hydrocarbon-contaminated air!