How do you usually mix your oxygen for diving? Every dive shop seems to have its own way, some are a bit old-school and need more effort, while others make the process feel easy and stress-free.
In this guide, we’ll take a closer look at the two main ways of making Nitrox and see which one really makes sense for safety, efficiency, and everyday diving life.
What is Nitrox?
Nitrox, often called Enriched Air Nitrox (EANx), is any mix of nitrogen and oxygen with more oxygen than the 21% found in normal air.
By breathing this higher oxygen content, divers can stay underwater longer without hitting their no-decompression limits and can also shorten their surface intervals. That is why Nitrox has become the most popular specialty gas in recreational diving.
What Is Partial Pressure Blending?
Partial pressure blending is the classic, hands-on way to make Nitrox. First, a set amount of pure oxygen is added to an empty, oxygen-clean scuba tank. After that, the cylinder is filled with regular compressed air until it reaches the right pressure, creating the chosen Nitrox mix.
To do this safely, you need a trained gas blender, a blending panel, and a steady supply of oxygen cylinders. The method is flexible because it can produce higher oxygen mixes used in technical diving, but it also comes with extra work and more risk.
Each tank takes around 20–30 minutes of careful attention, and the accuracy depends on precise math. The biggest safety issue is that it requires handling pure oxygen at very high pressures, which can be dangerous if mistakes are made.
What is a Nitrox Membrane System?
A Nitrox membrane system changes how Nitrox is made. Instead of blending each tank by hand, it creates Nitrox automatically in a steady flow. The trick is not adding oxygen but removing some of the nitrogen from normal air.
Here’s how it works:
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A low-pressure compressor pushes air into the system at about 10 bar.
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The air first passes through a refrigerant dryer, which removes moisture.
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It then goes through a three-stage filter: a pre-filter, an activated carbon filter, and a fine 0.01-micron filter that clears out any remaining particles.
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The clean air reaches the membrane. Here, nitrogen molecules are separated out, leaving behind oxygen-rich air. An adjustment valve fine-tunes how much nitrogen is removed, letting you control the final oxygen percentage.
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Finally, the enriched air (Nitrox) is sent to a high-pressure compressor, which fills scuba tanks or a storage bank.
Because this process happens at low pressure, there’s no need to handle or store pure oxygen at high pressure. That makes membrane systems safer, simpler, and more reliable.
Now, let’s see what Stefan has to say about a Nitrox Membrane System:
Safety Comparison
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Operational Efficiency
The biggest difference between the two systems is how they keep up with daily diving needs.
Partial pressure blending
This way makes Nitrox one cylinder at a time. Each tank requires close attention from a blender, and the process can take 20–30 minutes before the cylinder is ready to use.
For a small number of fills, this works fine, but it quickly becomes a bottleneck when dozens of tanks are needed.
Nitrox Membrane System
By contrast, a membrane system produces Nitrox in a continuous flow. Instead of preparing each tank individually, the system enriches air automatically as it runs, allowing multiple cylinders to be filled back-to-back with the same speed as regular air fills.
For busy dive centers or a liveaboard, this difference is huge. A continuous supply means divers are not left waiting between dives, staff spend less time tied up at the blending bench, and the operation runs with a smoother rhythm.
Why Dive Operators Choose Membrane Systems
Partial pressure blending still has a role, especially when divers need very specific mixes for technical dives. But for most dive centers and liveaboards that fill tanks every day, membrane systems are the smarter choice.
By choosing a membrane system, you make your dive operation safer, more reliable, and easier for staff to manage. Divers get consistent Nitrox on time, and your team can focus more on delivering great dive experiences rather than worrying about gas logistics.
If you are ready to simplify your Nitrox production and improve daily operations, NRC’s Nitrox membrane systems are designed for professional dive operators like you.
Explore NRC’s Nitrox systems to find the right solution for your dive center!
Frequently Asked Questions
Do I need an oxygen bank for a membrane Nitrox system?
No. This is one of the biggest advantages. The system generates Nitrox on demand from the surrounding air, completely eliminating the need to purchase, store, or handle high-pressure oxygen cylinders.
Can membrane systems produce Nitrox up to 40% O₂?
Yes. Most commercial membrane systems, including NRCs, are designed to produce Nitrox with oxygen percentages up to 40%. This range covers nearly all recreational and most technical diving applications.
What if I need higher oxygen mixes for technical diving?
For mixes above 40%, partial pressure blending is still a necessary method. However, many technical dive centers use a membrane system to produce a baseline EANx32 or EANx36, then use that as the starting point for partial pressure blending to higher concentrations. This still significantly reduces the amount of pure oxygen needed.
How often do the membrane filters need to be replaced?
The semi-permeable membrane is a durable, long-lasting component. With proper air filtration and regular maintenance according to manufacturer guidelines, a membrane can last for many years and thousands of hours of operation.