Gas Chromatography - Gas Supplies > Pure Nitrogen and Hydrogen Generators > Page 6
Pure Nitrogen Generators.
The nitrogen generator can also operate directly from the laboratory compressed air supply. General contaminants are first removed with appropriate filters and adsorbents and the purified air passes over layers of polymeric hollow fiber membranes through which nitrogen selectively permeates. The residual nitrogen-depleted air containing about 30% oxygen is vented to atmosphere. The nitrogen produced by the Air Products nitrogen generator contains less than 0.5 ppm of oxygen, less than 0.5 ppm of water vapor and less than 2.0 ppb of halocarbons or hydrocarbons. It can supply up to 1 l/min. at pressures from 60 to 100 psi.
In the Packard Hydrogen Generator, hydrogen is generated electrolytically from pure deionized water. Unfortunately, the technology used in hydrogen generators is largely proprietary and technical details are not readily available. The electrolysis unit uses a solid polymer electrolyte and thus does not need to be supplied with electrolytes, only the deionized water. The manufacturers claim the device generates 99.999% pure hydrogen with a reservoir capacity of 4 liter, and an output pressure that ranges from 2 to 100 psi. Other units can produce hydrogen flows that range from 0 to 125 ml/min. to 0 to 1200 ml/min. The oxygen, produced simultaneously with hydrogen at half the flow rate, is vented to air.