Lug a tank of gas to an experiment station, break the connection to the old tank, unhook the device that keeps the tank in place, pull out the empty tank and wrestle in a full one, secure the tank in place, attach the regulator and repeat, repeat, repeat. In some circumstances, a station can go through a tank—even multiple tanks—of gas every day. Beyond the mere hassle of all that tank swapping, it gets costly and even dangerous in some cases. Moreover, all the gas-line changing can contaminate the gas. To get around these challenges, gas generators can replace the tanks.
Kim Myers, gas generator global product manager at Parker Hannifin (Haverhill, MA), points out several reasons for turning to a generator. First, using gas generators can be safer than using tanks. The MythBusters episode of sheering off a tank valve depicts the danger when the tank plows clear through a concrete block wall and bores partway through a second one before it stops. Many lab managers turn to generators for convenience, as the opening analogy suggests. Cost also plays a part. In addition to paying for the delivery of the gas, Myers points out some related costs, including the time required to change the tanks and the managerial costs of maintaining the necessary supply of tanks. According to Myers, “Most generators pay for themselves in two years on the hard costs alone—just the cost of the gas in the cylinder.”
Gas generators can also make a better product. “When you generate gas at a plant,” Myers says, “the second you start doing anything with it, the gas starts to degrade, even as the producer starts to fill a tank from a big supply.” He adds, “A generator produces ultrahigh- purity gas, and it’s the same gas all the time.”
A generator for every job
The range of gas generators available keeps expanding. One class, the zeroair gas generator, doesn’t even sound as though it makes gas at all. “It’s a misnomer, really,” Myers says. This kind of generator makes air that is free of hydrocarbons, which is the kind of gas needed for many processes, including gas chromatography.
Other processes also need specific kinds of gas. For example, the Fourier transform infrared spectroscope, which is commonly used in quality assurance labs, runs better on gas that is free of carbon dioxide. So users need a gas generator that makes CO2-free air.
Customers can also buy generators that make a specific gas, such as hydrogen or nitrogen. In fact, Myers mentions that many customers want to replace the helium gas used in an application with hydrogen gas. “Helium is a nonreplenishable natural resource, and the world is running out of it,” Myers says. “There are some places where helium is rationed.” Although hydrogen can replace helium in many applications, customers often select a hydrogen-gas generator over tanks because of this gas’s flammable nature. “The generator includes only a small internal volume of the gas and produces just what you need,” Myers explains. A gas generator can also make a specialty blend. This can be required for some applications such as vehicle-emissions monitoring. “Combining purification, filtration and gas generation technologies enables us to produce gases with very specialized specifications,” Myers said.
Reliability represents a key trend across all gas generators, according to David Hemmig, director of sales at MATHESON (Montgomeryville, PA). “Features and fancy upgrades are nice,” he says, “but customers want reliability.” To Hemmig that means years of trouble-free performance. In zero-air gas generators, for example, Hemmig says that you should need to change the air filter only once a year.
Feeding forensic platforms
Gas generators also help out in some areas of applied technology. For example, forensics combines the expertise of medical research and law enforcement. This field uses liquid chromatography/mass spectroscopy (LC-MS) to analyze a wide range of samples, and one government lab manager mentioned using nitrogen gas generators with this technology platform. He added that he and his colleagues include gas generators in a range of other systems, including hydrogen generators for flame-ionization detectors and for nitrogen and phosphorous detectors. Here the lab manager pointed out the safety benefits of a hydrogen-gas generator that make it preferable to a large tank.
This expert also noted that today’s gas generators don’t cause many problems, and they run and run. In fact, he laughed as he compared modern gas generators to the Energizer bunny. If he could get one improvement, it would be a gas generator that displays some digital information, such as the purity of the gas being delivered.
Another reason for more customers to use gas generators is that some instruments now require higher volumes of gas. The biggest growth in the gas generator market, though, comes from LC-MS platforms. In that case, the generators often need to be smaller. “Lots of the labs using LC-MS are very small,” Myers says, “and a generator takes less space than tanks of gas.”
In a gas generator with an integrated compressor, Hemmig points out, the noise can be bothersome. So his company developed a nitrogen gas generator in which the compressors can be detached and moved outside the lab. Myers added that noise presents a health concern and says, “Parker has developed products that use compressors that are no louder than a refrigerator.”
Some customers need gas generators that capture performance data. Myers says, “This is growing out of the pharmaceutical industry, where they want to track everything, including gas-generator calibration and performance, such as pressure or flow.”
As gas generators meet more needs and grow increasingly reliable, more applications could arise. Users will find even more reasons to swap out tanks for a generator. It can make lab life simpler, safer, more economical and more successful.