Problem: Gas generators have become an alternative to high-pressure gas cylinders for supplying laboratory applications with high purity hydrogen, nitrogen, and zero-air. Until now, there has been no generator option for supplying high purity oxygen. Small pressure swing adsorption (PSA)-based oxygen generators are available for medical applications but do not offer the high purity generally required in the laboratory. The most common applications for high purity oxygen are instruments that combust samples for elemental, gravimetric, or calorimetric analysis. These analyses are important for a wide array of products, including food, feed, soil, fertilizer, oil, plastics, coal, metals, and minerals. In all of these applications, the oxygen is typically supplied via high-pressure cylinders. These cylinders need to be changed out periodically, which can lead to an interruption of the process, down-time, and recalibration of equipment. Furthermore, cylinders need to be maintained in inventory, and users must weigh the costs of returning a portion of the cylinder contents unused versus the risk of down-time or lost work due to cylinder run-outs.
Solution: Praxair, Inc. has developed the first ultra-high purity oxygen generator able to meet the needs of laboratory instrumentation. The underlying proprietary process is based upon solid state electrochemistry in which a dense ceramic membrane both separates oxygen from the surrounding air and pressurizes the oxygen up to 250 psig in a single step without any moving parts. Oxygen is ionized at the membrane surface, and the resulting ions are selectively conducted through the dense membrane tube wall to recombine inside the hollow interior of the tube as high pressure oxygen gas that is at least 99.999% pure. The lack of rotating compression components means that the process is extremely quiet and free from the risk of compressor failure that often plagues conventional generator approaches.
This patented process and technology is commercially available in Praxair’s StarGen ultra-high purity oxygen generator. Current StarGen generator models can generate either one or two liters per minute of oxygen. The system stores the generated oxygen in an onboard tank capable of holding up to 1500 liters (NTP) of oxygen at 250 psig. Users can draw oxygen from the storage tank at a much higher rate than the nominal generation capability until the tank is depleted. The generator senses when oxygen has been used and automatically refills the tank. The unit can also be installed quickly and provides robust, reliable performance with only periodic filter cleaning or replacement for routine maintenance.
This particular generator has been designed to provide a safe, consistent, and continuous supply of ultra-high purity oxygen for laboratory applications. An ultra-high purity oxygen generator such as this can improve lab productivity by eliminating cylinder handling, re-calibration of equipment after cylinder change-out, downtime and lost work due to cylinder run-outs, and cylinder inventory management. The low pressure storage tank enables the system to deliver a broad range of oxygen supply rates while dramatically reducing the volume and pressure of oxygen stored in the lab compared to cylinders.
For more information, visit www.praxairdirect.com/SpecGas or contact Praxair marketing manager of laboratories and life sciences Robert Sever, PhD at Robert_Sever@praxair.com or 630-320-4212.