Reliability, Control Key Issues
Nitrogen and zero air generators, for example, often use compressors to bring air into the system. The zero air generator “fine tunes” the product by removing hydrocarbons. “But the compressor is the weak link,” Hemmig says.
For nitrogen generators, the compressor serves a similar purpose, but separating pure nitrogen from air (which is 78 percent nitrogen) is slightly more difficult. Membranes represent the established technology, while units from Air Products (Allentown, PA), for example, use pressure swing adsorption. Regardless, when the compressor fails, nitrogen generation ceases.
“Failure rate is why we avoid compressors,” Hemmig emphasizes. “We do have models that use them, but we prefer to sell the ones without compressors because they’ll work forever.”
The alternative to compression is bringing in tanks of compressed air, which Hemmig says is no big deal. “Companies are used to gas cylinders. We believe a gas generator should be at least as reliable as a cylinder.”
House air is also a possibility, but users must first remove ubiquitous pump oils before allowing house air into generators. “Systems need to be as oil-free as possible.” Matheson and other firms sell in-line purifiers to remove oil in house air.
Hydrogen gas generators to the rescue
Reliability is a theme in hydrogen generation as well, although these systems work on the principle of water electrolysis and do not require gas compression. The ongoing helium shortage has created a robust market for hydrogen in gas chromatography.
Hydrogen was always part of GC instruments that used flame ionization detection (FID). Today, with helium in short supply, companies are turning to hydrogen as a carrier gas, which has caused a boom in gas generator sales.
“The shortage remains a hot topic,” says Kim Myers, global product manager at Parker Hannifin (Haverhill, MA). “Many companies today are rationing helium or have no access to it whatsoever. Those who can get it are paying five times as much as a few years ago.”
Thanks to helium’s scarcity, vendors of gas generation equipment are enjoying unexpected assistance from instrument companies that now write articles and make presentations on the benefits of hydrogen carrier gas.
Myers explains, “Think about it. GC has a heater and a small enclosed space, and the gas is not burning off as it does in FID. People think ‘Boom!’ But because they want to keep selling instruments, those companies are now singing the praises of hydrogen and are helping customers switch over from helium. Companies like Shimadzu, Thermo, and Agilent are blazing a trail for us.”
Several vendors, including Agilent, provide hydrogen leak detectors.
In the past year, Parker has launched products with higher flows and pressures, greater reliability, and interconnectivity, which help labs replace cylinders with generators. The company has also innovated with system software that allows load balancing, which benefits primarily high-volume users. Load balancing allows multiplexing up to 32 hydrogen generators into a single manifold with simultaneous independent control.
If one generator fails, the remaining units pick up the slack to rebalance back to the original aggregate production rate. No generator works harder than any other.
Load balancing also enables control and performance monitoring of a network of hydrogen generators through a USB connection to a computer.
For additional resources on Laboratory Gas Generators, including useful articles and a list of manufacturers, visit www.labmanager.com/gas-generators