SMC NMG Membrane Nitrogen Generator: Point-of-Use Nitrogen from Compressed Air
2026-11-10Plenty of machines need only a trickle of nitrogen: a few litres per minute to blanket a UV curing zone, keep resin in a moulding hopper from oxidising, or assist a fibre laser. Feeding them from cylinders means swapping bottles and watching gauges. SMC’s NMG series membrane nitrogen generator takes a different route: connect clean compressed air and get nitrogen-enriched air right at the point of use, with no electrical power needed to generate it. This guide sticks to what SMC publishes on its new-products page, its web catalogue and the NMG catalogue (CAT.ES30-29B), so you can judge whether NMG fits your machine and which tables to read before you choose a model.
The short answer
There are eight NMG models: three single membrane modules (400, 800 and 1300 types), two double membrane modules and three manifolds. At SMC’s rated conditions (0.7 MPa inlet, 25 °C inlet air and ambient) and 99.9% outlet nitrogen concentration, outlet flow runs from 6.0 to 108 L/min (ANR). Operating pressure is 0.3 to 1.0 MPa, proof pressure 1.5 MPa, and ambient and fluid temperature −5 to 60 °C with no freezing or condensation. If you need around 99.9% within that flow band and already have compressed air on site, NMG is worth a look. Two caveats up front: it uses far more compressed air than the nitrogen it delivers, and the outlet gas must never be used for breathing.
How it works
The membrane is a bundle of hollow fibres. As compressed air flows through, oxygen permeates the fibre walls easily and leaves as oxygen-enriched purge air; nitrogen does not, so nitrogen-enriched air comes out of the outlet. The purge air discharge port is Rc1/2, and the purge cover can be removed so you can pipe the purge air away (SMC says to read the operation manual first).
One definition matters: SMC’s “nitrogen concentration” is the total of everything except oxygen in the air, so it includes argon, CO2 and water vapour. If your process is sensitive to those, check separately.
The eight models at a glance (rated conditions, 99.9%)
| Construction | Model | Type | Outlet N2-enriched air flow, L/min (ANR) | Weight |
|---|---|---|---|---|
| Single module | NMG50A-04N1 | 400 | 6.0 | 3.2 kg |
| Single module | NMG50A-08N1 | 800 | 20 | 6.4 kg |
| Single module | NMG50A-13N1 | 1300 | 36 | 10.7 kg |
| Double module | NMG50A-1308 | 1300 + 800 | 44 | 17.5 kg |
| Double module | NMG50A-13N2 | 1300 + 1300 | 56 | 21.5 kg |
| Manifold | NMG50B-08N2 | 800 × 2 | 40 | 16.3 kg |
| Manifold | NMG50B-13N2 | 1300 × 2 | 72 | 24.2 kg |
| Manifold | NMG50B-13N3 | 1300 × 3 | 108 | 35.4 kg |
Common to all: fluid is air; inlet air purity ISO 8573-1:2010 [1:6:1]. Outlet purity is [1:3:1] for NMG50A-04N1 and [1:2:1] for the other models, which is what SMC means by “outlet purity class 2 (humidity)”. The 1300 type, the double modules and the manifolds are the recent additions.
Sizing: purity, pressure and flow move together
99.9% at 0.7 MPa is just one operating point. Raise the inlet pressure or accept a lower purity and the same unit delivers more flow. From SMC’s characteristics table (25 °C inlet, 0.7 MPa), single modules:
| Model | Outlet flow at 99.9% | at 99% | at 95% | Inlet air flow at 99.9% (reference) |
|---|---|---|---|---|
| NMG50A-04N1 | 6.0 | 14.0 | 41.0 | 43 |
| NMG50A-08N1 | 20 | 40 | 100 | 143 |
| NMG50A-13N1 | 36 | 85 | 213 | 257 |
All values in L/min (ANR). Look hard at the last column: 36 L/min of 99.9% nitrogen-enriched air from an NMG50A-13N1 needs roughly 257 L/min of inlet air. SMC requires the air supply to cover the outlet flow plus the purge flow; if it can’t, you won’t reach the rated flow or purity. Check your compressor and piping headroom before anything else.
Temperature matters too. SMC gives correction factors: at 99.9%, 1.03 at 15 °C inlet and 0.95 at 40 °C; at 98% and 20 °C the factor is 0.95. Corrected flow = table flow × factor.
Inlet air preparation is not optional
- SMC recommends inlet air of ISO 8573-1:2010 [1:6:1] or better, with a line filter (AFF), micro mist separator with pre-filter (AMH) and activated carbon filter (AMK) chosen to suit your incoming air. Solids or oil reduce performance or damage the unit.
- Keep water droplets out, and keep the supply’s pressure dew point below ambient temperature, or condensation will form inside. Take extra care against freezing below 10 °C ambient.
- NMG50A connects modularly to size 30 air preparation units and NMG50B to size 40; other sizes need a reducing adapter. Above 1500 L/min (ANR) inlet flow, SMC calls for AC50 size or larger. Units ship unassembled; you order the parts separately and assemble them.
For the basics of building the air prep train, see our SMC AF, AR, AL FRL selection guide and how to deal with moisture in compressed air. If drying is the issue, our SMC IDG50A-F03 membrane air dryer page covers a related membrane product.
Versus cylinders and PSA generators
- Versus cylinders: SMC points to no cylinder swaps, no gas-level checks and no refilling.
- Versus PSA (pressure swing adsorption): SMC says NMG takes less space, uses no chemical adsorbent and so needs no adsorbent maintenance, and runs on compressed air alone, while PSA needs solenoid valves and controls. SMC also states it is not subject to pressure vessel regulations; confirm how your local rules apply.
- Limits: high compressed air consumption, and a start-up delay. Higher purity takes longer; reaching 99.9% may take more than 30 minutes (reference). If you need instant purity or more than 108 L/min, look at other options.
Applications SMC lists
UV emitters and UV printers (suppressing oxygen inhibition), moulding machine hoppers, atmospheric nitrogen replacement in process chambers, 3D printers, filling machines, analytical equipment, automatic soldering, fibre laser assist gas and vertical pillow packaging. SMC adds that you should size for the purity each machine actually needs, not automatically for 99.9%.
Safety
- The outlet gas is nitrogen-enriched air. Never use it as breathing air: it can cause oxygen deficiency and asphyxiation. Install in a well-ventilated area and keep it ventilated in use.
- The purge air is oxygen-enriched. Keep it away from flames and combustibles.
- The units are heavy (up to 35.4 kg for the triple manifold); SMC recommends two or more people for handling.
Selection checklist
| Check | What to confirm |
|---|---|
| Purity | What the machine really needs (90 to 99.9%) |
| Flow | Peak and average L/min (ANR), matched against the characteristics table |
| Inlet pressure | Stable value within 0.3 to 1.0 MPa |
| Air supply headroom | Compressor covers outlet flow plus purge flow |
| Air quality | [1:6:1] or better; AFF/AMH/AMK fitted; dew point below ambient |
| Temperature | Inlet temperature and the matching correction factor |
| Installation | Flow direction (standard left to right, R = right to left), brackets, purge piping, ventilation |
Talk to us
Send your required purity, flow, supply pressure and current air preparation setup to doskee@dustry.ltd. We will help you list the points to confirm with SMC. You can also browse our SMC product category.
FAQ
Does NMG need electrical power?
Not for generating nitrogen. It needs only a compressed air supply.
Is 99.9% the same as pure nitrogen?
No. SMC’s figure is the total of all components other than oxygen, including argon, CO2 and water vapour.
Why is purity low right after start-up?
It takes time to reach target purity; 99.9% may take over 30 minutes (reference). Also check inlet air flow, pressure and temperature.
Can I use a standard filter only?
SMC recommends [1:6:1] or better inlet air, with AFF, AMH and AMK selected for your incoming air quality. Oil and particles reduce performance or damage the unit.
Where should the purge air go?
It is oxygen-enriched, so keep it away from ignition sources and ventilate. If needed, remove the purge cover and pipe it away from the Rc1/2 port.
Sources: SMC new products: Membrane Nitrogen Generator NMG Series; SMC web catalogue, NMG; SMC NMG catalogue CAT.ES30-29B (PDF); SMC Europe membrane nitrogen generators.