Aircraft Nitrogen Generators for Maintenance and Manufacturing
An aircraft nitrogen generator makes nitrogen from compressed air on your own site, at grades from 97 % up to 99.999 %: for tyres, shock struts, purging, the autoclave and the laser. A NITROBERG® generator is sized around what those points of use actually draw, and this page works through that before you choose a model.
What an Aircraft Nitrogen Generator Has to Deliver
On a maintenance site the nitrogen goes to four places. Tyres on braked wheels are filled in the wheel and brake shop and topped up again out on the line, and that is where most of the volume goes. Shock struts and hydraulic accumulators are charged on the aircraft, at a much higher pressure and in much smaller quantities. Fuel and hydraulic components opened for repair are purged, so that vapour and moisture are displaced before work starts and the part is dry when it goes back together. And in the fuel farm, storage and transfer equipment can be blanketed so that the atmosphere above the liquid stays out of the flammable range.
The manufacturing side draws nitrogen for different reasons. Composite parts are cured in an autoclave that is pressurised with nitrogen rather than air, because the heat the resin gives off during cure makes an oxygen-rich atmosphere under pressure a fire risk. Stainless parts cut on a laser need nitrogen as the assist gas to leave an oxide-free edge; the assist gas is chosen to suit the material, and titanium is cut under argon instead. Test benches and component rigs are purged so that residual vapour and moisture are flushed out before and after a run.
Across that list, the point of use that takes the most gas and the point of use that sets the highest purity are not the same one, and the gap between them is wide. One technology covers all of it. Compressed air passes through a bed of carbon molecular sieve that takes up oxygen, carbon dioxide and residual moisture far faster than it takes up nitrogen, and two beds alternate so that one produces while the other regenerates at lower pressure. The PSA nitrogen generator page describes that cycle step by step, and the carbon molecular sieve article explains why that one component sets the ceiling on what the machine can reach.
What Nitrogen Purity Each Aviation Task Needs
Purity on a site is usually specified once, for everything, by whoever happened to have the most demanding process. In aviation that is an expensive habit, because the lowest and the highest requirement on the list below are a long way apart. The grades shown are the ones normally specified in practice. Treat them as a starting point and confirm them against the maintenance documentation and your own process specifications, because the requirement moves with the aircraft type, the component and the shop procedure.
Read down the right-hand column rather than across the rows.
| Task | Typical grade | What the nitrogen does | Sizing driver |
|---|---|---|---|
| Tyres on braked wheels | 97 % and above | Inert fill that holds the oxygen content in the tyre below the limit | Volume |
| Shock struts and hydraulic accumulators | 99.5 % and above | Gas spring in the strut, pre-charge in the accumulator | Volume |
| Purging fuel and hydraulic components under repair | 99.5 % and above | Displaces vapour and moisture before and after work | Volume |
| Blanketing fuel farm storage and transfer equipment | 97 % and above | Holds the atmosphere above the liquid out of the flammable range | Volume |
| Autoclave curing of composite parts | 99 % and above | Pressurising medium that does not feed a fire | Volume |
| Laser cutting of stainless parts | 99.999 % | Assist gas for an oxide-free cut edge | Purity |
| Test benches and component rigs | 99 % and above | Purge gas and inert atmosphere | Volume |
Everything that moves real volume is marked Volume, and almost all of it is met well below 99.9 %. Only one row is marked Purity. If the laser and the hangar share a supply, the hangar runs at the laser’s grade and pays for it by the hour. That split is the usual case, and it turns around where the point of use with the highest grade is also the largest one: a laser running as base load, for instance, where the high grade sets the volume as well. Where a strut or an accumulator is charged to a published technical nitrogen specification rather than to a shop procedure, those specifications start at 99.5 %.
The tyre row is the one with a published requirement behind it rather than a shop convention, and it is worth reading closely because it sets the floor for the whole site. For tyres on braked wheels of transport aeroplanes above 34,019 kg (75,000 lb), the airworthiness requirement is that the gas mixture in the tyre contains no more than 5 % oxygen by volume. Several national rules apply the same 5 % limit from 5,700 kg upwards. The reason behind it is thermal. A tyre heated hard enough, by a dragging brake for instance, can release volatile gases from the liner, and oxygen in the trapped gas is what turns that into a fire in the wheel well. For a generator this is a comfortable number: the lowest grade in the NITROBERG® range is 97 %, which clears the limit with room to spare, and it is the grade with the lowest compressed air demand in the whole range.
How Much Compressed Air Each Grade Takes
Every NITROBERG® size consumes a defined amount of compressed air for each cubic metre of nitrogen it delivers, and on an aviation site that is the figure the compressor room has to carry. The ratio, called the air factor, is the same across the range and depends only on the purity you set.
| Purity | 97 % | 98 % | 99 % | 99.5 % | 99.9 % | 99.99 % | 99.995 % | 99.999 % |
|---|---|---|---|---|---|---|---|---|
| Air factor | 2.3 | 2.3 | 2.6 | 2.9 | 3.4 | 4.6 | 5.2 | 6.4 |
Put a site figure into it. A maintenance base drawing 60 Nm³/h for tyres, struts and purging needs around 138 Nm³/h of compressed air at 97 %. Specify 99.999 % across the whole site instead, because one laser in the parts shop needs it, and the same 60 Nm³/h needs around 384 Nm³/h: close to three times the compressor, three times the electricity and three times the compressor room, for gas quality that a tyre cannot use.
That is the argument for splitting the supply rather than centralising it. The laser on its own high-purity line, the shop and the infrastructure on their own cheaper one, each sized for what it does. The cost and payback article works through the running costs behind that decision.
How to Size a Nitrogen Generator for Aviation Work
List Every Point of Use Separately
Take a figure for each point of use: the wheel and brake shop, line maintenance, strut and accumulator charging, the purging station, the autoclave, the laser, the test rigs. Then separate what draws continuously from what draws in bursts. A wheel change is a peak rather than a running load, and a system sized on the sum of all peaks is a system nobody needs.
Let the Task Set the Purity
Take the most demanding entry on your list, then ask whether it belongs on the same supply as everything else. On an aviation site the answer is usually that it does not, because the tyre duty and the laser duty are nearly a factor of three apart in compressed air.
Decide on Buffer and Reserve
An aircraft that has to be back in service for its slot changes the sizing before any model is chosen. The buffer vessel holds a reserve, and how large it has to be follows from the longest interruption your operation can absorb. Work that out before you compare models.
Check the Compressed Air, Quantity and Quality
Multiply the flow from step 1 by the air factor and you have the demand on the compressor room. Air quality counts as much as quantity and is the part that gets forgotten: oil carry-over and residual moisture shorten the life of the carbon molecular sieve, so an undersized dryer costs more over five years than a slightly undersized compressor. NITROBERG® generators require compressed air to ISO 8573-1:2010 Class 1.4.1 at 7 bar(g).
Need Sizing for Your Application?
Send us the points where nitrogen is drawn and your operating data. Our engineering team will size the generator and confirm the configuration. If it is quicker to talk, call +49 2151 568 9550.
Getting the Gas Up to Servicing Pressure
A buffer vessel and a compression stage take the nitrogen up to servicing pressure, and the shop line or the service cart is filled from there. What changes when a generator comes in is where the gas comes from. The way a wheel or a strut is actually serviced stays as it is.
The generator makes the gas and delivers it into the air main at network pressure. On its own it does not raise that gas to the pressure a tyre valve or a strut charging point works at, which is why the compression stage is laid out with the system. Tyre servicing works at pressures above a shop air main, and strut and accumulator charging far above that again.
For planning, that means pressure belongs in the first set of figures you hand over, next to flow and purity, because it decides what sits between the machine and the point of use. Where a site has no suitable compressed air network to start from, the nitrogen generation package combines the generator, compressed air generation, treatment, storage and control in one pre-assembled unit, in plug-and-play configurations for NITROBERG® 500 to 900.
On-Site Nitrogen Compared with Cylinder Packs and Liquid Supply
Cylinder packs and liquid nitrogen tanks both deliver purity, and both keep costing while the hangar is quiet. Rental runs through quiet weeks, evaporation runs overnight, contracts carry price escalation clauses, full and empty cylinders both take floor space in a hangar where floor space is expensive, and the pack tends to run out on the aircraft that has to go out tonight. On-site generation replaces that with an investment and an electricity bill. Compared with liquid nitrogen supply, a Berg PSA generator typically pays for itself within two to three years.
Purity You Configure
The generator is set to the grade your tasks need rather than to the highest one on the site. That matters here, because the duty that moves the most gas sits at the bottom of the purity range and pays the lowest air factor.
Standard Wear Parts
Filters and consumables are standard items from the open market, ordered like any other stores item in the hangar. The purchase does not come with a parts programme attached, and it is worth asking every supplier you compare where their filters come from.
Capacity That Follows the Site
A single wheel and brake shop and a maintenance base with its own parts production sit far apart in demand, and both are inside the NITROBERG® range of 1.2 to 1,709.1 Nm³/h. Capacity is added as the operation grows.
Direct Access to Engineering
Sizing and pressure questions go to the engineers who design the machines. Delivery, commissioning and service come from one source within the BERG Group, with three years of warranty as standard and up to five years with a service contract.
NITROBERG® Sizes for Hangar, Maintenance Base and Plant
Five sizes out of the NITROBERG® range cover the band a hangar, a maintenance base or a parts shop normally falls into, shown at the three grades that matter on this page. Smaller duties sit at the bottom of the range: the NITROBERG® 500 delivers 10.7 Nm³/h at 97 %.
| Model | N₂ at 97 % | N₂ at 99 % | N₂ at 99.999 % |
|---|---|---|---|
| NITROBERG® 500 | 10.7 Nm³/h | 7.1 Nm³/h | 1.2 Nm³/h |
| NITROBERG® 800 | 42.8 Nm³/h | 28.4 Nm³/h | 4.8 Nm³/h |
| NITROBERG® 1000 | 89.9 Nm³/h | 59.6 Nm³/h | 10.1 Nm³/h |
| NITROBERG® 1200 | 145.5 Nm³/h | 96.6 Nm³/h | 16.3 Nm³/h |
| NITROBERG® 1400 | 286.8 Nm³/h | 190.3 Nm³/h | 32.2 Nm³/h |
The columns show three reference grades; where a duty sits between them, the grade is set in the sizing. Compare the two outer columns. The machine that delivers 145.5 Nm³/h at 97 % delivers 16.3 Nm³/h at 99.999 %, a factor of nine out of the same box. Specify a whole site at the grade one laser needs and you buy several machines where one would have done.
The range carries on above these sizes to 1,709.1 Nm³/h, where one machine supplies several buildings on a site. Applicable NITROBERG® pressure equipment is conformity assessed under PED 2014/68/EU within the certified scope. Engineering and manufacturing are Made in Germany.
Laser cutting, the duty that sets the purity on this page, has a page of its own: the cutting side is described on the laser cutting page. The full NITROBERG® range sits on the nitrogen generator overview.
FAQ: Aircraft Nitrogen Generators
The requirement is written as an oxygen limit rather than as a nitrogen grade: for tyres on braked wheels of transport aeroplanes above 34,019 kg, the gas mixture in the tyre must contain no more than 5 % oxygen by volume. Every grade a NITROBERG® generator produces clears that, the lowest one at 97 % included. Purity is a configuration decision taken when the system is sized rather than a fixed property of the machine, so the question worth asking is which of your other consumers needs more than the tyres do. Higher grades cost noticeably more to run, because the compressed air needed per cubic metre of nitrogen rises with the purity you set.
No. Berg GaseTech builds the nitrogen supply on the ground, for the hangar, the maintenance base, the fuel farm and the production shop.
Yes, with a buffer vessel and a compression stage between the generator and the point of use. A generator delivers into the compressed air network at network pressure, and tyre, strut and accumulator charging all work above that, so the step up is part of the system design. That is why pressure belongs in the enquiry alongside flow and purity. Tell us the charging pressures you work at and we will lay the configuration out around them.
Yes. The generator runs on compressed air, and the amount depends on the purity you choose: multiply your nitrogen demand by the air factor, which runs from 2.3 at 97 % to 6.4 at 99.999 %. Air quality matters as much as quantity, because oil carry-over and residual moisture shorten the life of the carbon molecular sieve. Where a site has no suitable network, the skid-mounted package brings its own compressor and air treatment.
The buffer vessel holds a reserve, which covers short interruptions and gives time to react. Where a cure cycle is running in an autoclave, that time does not help: the part stays under pressure and at temperature until the cycle has run, so what has to be bridged there is the rest of the cycle. On a site where aircraft have to make their slots, the answer is worth having before a model is chosen. Beyond the buffer, a reserve supply remains part of a sensible plan. The reserve strategy is defined together with the system design and the requirements that apply at your site.
It can, and the question is whether it should. A shared supply runs at the purity of its most demanding consumer, so tyre and strut servicing would run at the grade the laser needs and pay for the compressed air that goes with it, which is close to three times what the same volume costs at 97 %. Where the parts shop needs 99.999 % and the hangar does not, a separate high-purity line for the laser is usually cheaper than lifting the whole site to that grade.
No. The wear parts are standard components rather than a proprietary programme, which keeps the running cost open to competition: filters can be sourced where you want and service quotes can be compared. Over the service life of the machine that usually counts for more than the difference in purchase price. The warranty runs for three years as standard and up to five years in combination with a service contract.