Gas generator

Buying guide

The output specification settles most of these purchases before anything else is considered, because a generator is bought to feed a named instrument and that instrument fixes the flow, the pressure and the purity it needs. A gas chromatograph with a flame ionisation detector wants hydrogen at a defined flow and a nitrogen or zero air carrier; an LC-MS source wants high-flow nitrogen at a nitrogen purity the vendor states in percent. Reading the detector or source manual first, then matching a generator to the flow in litres per minute and the purity grade, is the order that avoids an underspecified unit sitting idle. A regulator or a purification system is chosen the same way, from the downstream requirement rather than from the generator alone.

Condition carries more weight here than the datasheet suggests, because a used gas generator is a machine with a running history. The membrane or PSA bed in a nitrogen unit degrades with hours of use, a hydrogen generator's electrolytic cell and desiccant have a service life, and a laboratory air compressor's duty cycle and noise level change as seals wear. What to verify on a used unit is the accumulated run time if the controller logs it, the state of any consumable filters and dryers, and whether the purity still meets the stated grade under load rather than at rest. A compressor can be run and listened to; a generator's output purity is harder to confirm without the instrument it feeds, so the listing detail and the supplier's description matter.

The price band runs from EUR 6 to EUR 154.960, and that spread covers two different things a buyer might be after. At the low end sit gas pressure regulators and individual components, where cost is a minor line in a budget. At the high end sit complete nitrogen or hydrogen generators and full gas supply systems, where the figure is a capital decision. The average listing sits at EUR 2.412. The brands that occupy these bands are Jun-Air, Peak Scientific, Linde, Agilent, Various: Jun-Air is known for laboratory air compressors, Peak Scientific and Agilent for instrument gas generators, and Linde for supply and purification. Where a budget is tight, refurbished and used units are listed for sale at prices below new, and 603 of the current listings are used, so the comparison a buyer makes is mostly between used examples rather than against new stock. Warranty is arranged in consultation for the specific listing.

Types of Gas generator

Which gas generator types are listed?

Among the listings that specify a type, the catalogue divides into a few recognisable groups. Laboratory gas generators and the broader gas generator entries are the instruments that synthesise a gas on demand: nitrogen units that strip oxygen from compressed air, hydrogen units that electrolyse water, and zero air units that oxidise hydrocarbons out of an air stream. These are the devices a chromatography or mass spectrometry bench depends on, and in molecular biology and proteomics laboratories they feed the LC-MS instruments used for protein identification and the GC-MS systems used in metabolomics. A hydrogen generator built for a flame ionisation detector is a different animal from one built as a carrier gas source, so the intended detector decides which a buyer reaches for.

Laboratory air compressors form the second group, supplying the clean, dry compressed air that both pneumatic instruments and many generators take as their input. They are also used for actuating valves and driving sample preparation equipment. Gas pressure regulators step a supply down to a working pressure at the point of use, and gas purification systems and gas supply systems sit either side of them, scrubbing moisture, oxygen and hydrocarbons from a line or routing gas from a source to several benches. Together these support the whole chain from a cylinder or a generator to the instrument inlet, and in a cell culture suite they also condition the carbon dioxide and nitrogen supplies feeding incubators.

The brands behind the gas generator listings

The brands that recur are Jun-Air, Peak Scientific, Linde, Agilent, Various. For a buyer, that mix tells you where to look for parts and how easy a comparison will be. Jun-Air compressors are widely enough installed that seals, filters and service parts are straightforward to source, and parts can be sourced via Questpair. Peak Scientific and Agilent generators are tied closely to the chromatography and mass spectrometry instruments they were designed around, so a model name usually maps cleanly onto a known flow and purity figure, which makes two listings easy to compare. Linde appears on the supply and purification side. The "Various" entry covers the long tail of regulators and components where the maker matters less than the fitting and the pressure rating.

What a used gas generator costs here

New, used and refurbished units all appear, and the catalogue leans heavily towards used: 603 of the listings are used. Prices range from EUR 6 to EUR 154.960. That spread is the distance between a single regulator and a complete supply installation rather than a measure of quality, and the average of EUR 2.412 sits well toward the lower end, which reflects how many of the entries are components and compressors rather than full generators. Used and refurbished units are listed below new prices, so for most of these the practical comparison is between one used example and another.