The Atomic naming system is a simple affair, with the letter denoting the material used: ‘B’ for Brass, ‘Z’ for Zirconium, ‘T’ for Titanium and, in the case of this ‘M’ model, Monel. The number denotes the edition.
Monel is a nickel-based alloy that contains between 29 and 33% copper. The alloy exhibits high corrosion resistance in acids and alkalis, high mechanical strength, good ductility and a low coefficient of thermal expansion.
Most importantly, it is compatible with the use of high-pressure oxygen.

First Stage
Employing chrome-plated brass for the main body and monel for key internal components, the first stage is a high-flow piston design with four low-pressure ports set around a swivel turret and a fifth central lp port at the tip.
Two high-pressure ports are fixed within the main body.
The first stage is environmentally sealed for freeze and contamination protection.
The M1 is factory-ready for non-dedicated nitrox mixes up to 50% or dedicated oxygen mixes up to 100%, although at anything above 50% you’ll have to follow Atomic’s strict guidelines on dedicated oxygen regulator use.
Let me explain: contaminates such as oils can be transferred into cylinders when charged with air, especially in areas where clean air standards are uncertain. This oil can then contaminate the high-pressure components within the regulator’s first stage.
High-percentage oxygen at high pressures can cause this oil to spontaneously combust, producing toxic carbon monoxide and damaging the internal components.
The M1 is built for high oxygen use, but if this is your intention it must be dedicated for that use only. Alternatively, it can be safely used interchangeably with compressed air or nitrox mixes up to 50%.

Second Stage
The second stage is constructed using high-grade polymers with precision-machined zirconium plated brass, 316 stainless steel and titanium components.
It has a fixed thermal heat-sink, which makes it suitable for coldwater diving, and Atomic’s patented seat-saving orifice.
This is a clever design that lifts the valve away from its seat when the regulator isn’t in use, ensuring that it doesn’t become engraved, and thereby prolonging its life. The result is a two-year or 300-dive service interval.
Unlike most regulators, the front cover on the M1 has its inlet ports around the edge as opposed to the front. This ensures that water flow from strong currents, or when using a scooter (DPV), won’t press against the diaphragm and cause an unwanted increase in gas flow.
Other features include Atomic’s patented Automatic Air Flow (AFC), which is a pressure sensor that adjusts the venturi vane according to depth, a rapid-adjustment knob to manually de-tune the second stage, and an enlarged exhaust opening with widened ports to distribute exhaled bubbles away from the diver’s face.
Last but not least is a comfort-fit mouthpiece, which is formed from dual silicon and has tear-resistant bite tabs.

Under Water
I started a week’s diving, having configured this regulator for recreational depths using a single tank set-up, and set off to explore the reefs around Egypt’s Ras Mohammed marine park.
The first-stage low-pressure ports are set in pairs around the swivel turret, which makes hose-configuration a doddle, putting everything exactly where I want it.
My first impressions as I put the M1 through my standard set of tests were of a regulator built to exacting standards using high-quality materials. The regulator breathed extremely smoothly at shallower depths, without the slightest hint of a freeflow when I hit the water.
I inverted myself to see if there was any leakage when it was used upside-down, and the mouthpiece remained dry. Nor was there a freeflow when I spat the second stage out.
Everything seemed simple but effective, especially the purge, which is big, easy to locate and operates superbly, progressively increasing airflow the more it’s depressed. It easily cleared any water from my mouth, without trying to blow a hole in the back of my head.
I found the rapid-adjustment knob easy to locate and to use as well, but at shallow depths there seemed to be little if any difference in performance. It wasn’t until I took the reg down to 50m on a technical dive that it came into its own, with a discernible difference in breathing resistance as I detuned the reg.
On the deeper dives this regulator seemed to come to life. Don’t get me wrong, it was first-rate at recreational depths, it’s just that it became even better the deeper I went.
The enlarged exhaust with wide ports meant that bubble distribution was excellent, and I also found it easy to exhale.
The attention to detail is second to none, with little touches such as the silicone mouthpiece that make this package ooze class. The mould-lines removed around the edges to create a smooth surface that didn’t rub the corners of my mouth made long, repetitive dives a joy.
However, unlike other models in the Atomic range the M1 on test lacked a second-stage swivel, and I found it a little stiff, especially with the heavy rubber intermediate-pressure hose fitted as standard.
While Atomic will fit a swivel as an option, hardcore tec divers are likely to see this as a failure point.
Most importantly, as an all-rounder the M1 lacks the facility to change the hose-configuration to the left for true versatility when configured for a twin or sidemount set-up.

There are some pretty good regulators in today’s marketplace, especially in terms of build quality and performance. I have dived with a few of these high-end models recently and my past interpretation of what makes a good performer has changed considerably.
In my opinion the Atomic M1 is an extremely good regulator, its performance second to none, but for what is a claimed all-rounder it lacks total versatility.
However, like all Atomic products the design, attention to detail, materials and performance still put it right up there with the very best in its class.

PRICE M1 £526, M1 Octo £220
FIRST STAGE Jet-seat piston
PORTS 5lp, 2hp
CONNECTIONS DIN, A-clamp, M26 x 2
SECOND STAGE Pneumatically balanced poppet with seat-saving orifice.
CONTROLS Automatic Flow Control (AFC), rapid-adjustment knob.
NITROX Non-dedicated EAN 50%, dedicated EAN up to 100%.
WARRANTY Limited lifetime (not contingent on proof of purchase).
SERVICE INTERVAL 2 years / 300 dives
DIVER GUIDE width=100% width=100% width=100% width=100% width=100% width=100% width=100% width=100% width=100% width=100%