EXTREME CONDITIONS DIVING:

Extreme cold water diving conditions pose a unique challenge to divers and equipment alike. Extreme temperatures can cause regulator “freezing” during which a regulator might experience a free-flow. While this is not an imminent threat (because air continues to flow from the second stage) Halcyon systems greatly limit the risk of this occurrence. All Halcyon regulator systems are CE approved for 4300psi cold water diving; in fact we even exceed the CE cold water requirements. To further reduce regulator freezing Halcyon’s H-50D uses a dry ambient pressure chamber. Meanwhile Halcyon second stages feature precision molded carbon fiber and technopolymer valve housing and components which also contribute to their lightweight features and corrosion resistance.

Halcyon's H-75P offers many refined features that ensure consistent delivery with performance that ranks among the very best in our industry. The stable, intermediate pressure provides precise delivery of air to the second stage. This means you will experience a remarkable ease of breathing while diving in all environments; this is true at nearly any tank pressure and within almost any water temperature. This sophisticated technology is among the best in the industry freeing you to get the most out of your diving.
Air balanced flow-through piston delivers an optimal amount of air to the second stage, remaining unaffected by changes in tank pressure. Lightweight & responsive components create prompt adjustments to breathing demands in all conditions, temperatures or tank pressures. Enjoy the smoothest breathing regulator whether you are on the final hours of an extreme cave exploration or on a blue water ascent after a magnificent Grand Cayman wall dive.

• Five High-flow, Low-pressure Ports allow you to customize your hose routing for comfort and convenience. The Halcyon 360 degree swivel turret cap with high flow ports ensure the best air delivery possible with up to 15% more air than other LP ports. Combined with Halcyon's "long" primary hose and backup necklace your hoses can be configured where you need them. Whether diving a sophisticated rebreather or a simple, open water system you can create a configuration that supports easy movement, reduces jaw fatigue from ill-routed hose position and streamlines your diving profile.
• Two opposing high pressure ports allow you to choose where to route your SPG and allows the use of accessories. Most Halcyon divers route their pressure gauge to the left but the Halcyon H-75P allows flexibility with any configuration you choose; these options provide freedom to support personalized and advanced hose routing configurations.
• 300 Bar DIN first stage is the most secure connection available; our DIN fittings are compatible with a wide range of yoke conversion kits.
• Nitrox 40% compatible right out of the box so you can start diving without any additional concerns. Assemble your system, analyze your gas and go diving. We also offer Oxygen clean upgrade kits for the H-75P so you can enjoy these great features on all your deco bottles.
• Externally adjustable intermediate pressure allows a quick fine-tuning by a Halcyon service technician without fully disassembling the first stage.

The H-50D is a high performance diaphragm design that is fully sealed and purpose built for harsh conditions like ice or environmentally contaminated environments. Diaphragm first stages are historically popular with cold water divers and the H-50D was engineered for extreme conditions. Go dive extraordinary places with your H-50D and be confident that you have a rugged regulator that will meet all your demands.

• Balanced, environmentally sealed diaphragm provides better performance in cold water than any other diaphragm regulator while supplying consistent performance at varying tank pressures and depths; you will enjoy smooth, easy breathing throughout your dive. The dry, balance chamber, diaphragm design prevents the entry of water into the first stage mechanism and enhances a trouble-free operation; this is true even in the coldest conditions.
• Two opposing high pressure ports allow you to choose where to route your SPG and allows the use of accessories. Most Halcyon diver’s route their pressure gauge to the left but the Halcyon H-50D allows flexibility with any configuration you choose; these options provide freedom to support personalized and advanced hose routing configurations.
• Four low pressure ports allow you to customize your hose routing for comfort and convenience. The H-50D features four stationary low pressure ports with high flow options, ensuring the best air delivery with up to 15% more air than other LP ports. For maximum freedom, try the H-75P with its 360 degree swivel turret.
• 300 Bar DIN first stage is the most secure connection available; our DIN fittings are compatible with a wide range of yoke conversion kits.
• Nitrox 40% compatible right out of the box so you can start diving without any additional concerns. Assemble your system, analyze your gas and go diving. Oxygen clean upgrade kits are not available for the H-50D because it is not recommended to use 100% oxygen with a diaphragm first stage design. Please consider the H-75P with Oxygen Upgrade Kit if you require 100% oxygen service.
• Externally adjustable intermediate pressure allows a quick fine-tuning by a Halcyon service technician without fully disassembling the first stage.

Breathing underwater should feel natural and that experience is one of the things that most clearly separate Halcyon second stages from our competitors. As soon as you experience the smooth, high volume of air delivered by a Halcyon second stage you will be hooked. Our high quality second stage regulators provide diver adjustable controls for the ultimate in breathing performance.
Halcyon’s Halo second stage offers steadfast reliability and impeccable performance; two methods of breathing adjustment make it the top choice for demanding Halcyon divers.

• Balanced, downstream valve offers incredibly smooth breathing in all conditions. The design slightly offsets the force of the downstream air entering from the first stage, allowing reduced spring tension and a decreased inhalation resistance. Halcyon first stages are balanced, so the Halo is a perfect fit with either the H-75P or H-50D Halcyon first stage.
• Adjustable inhalation control refines breathing effort by way of an easy access control knob; this allows the demanding diver an opportunity to fine-tune the air delivery of the second stage. Meanwhile, our Aura second stage features a pre-set inhalation effort that suits the most common diving conditions and can be fine tuned by an Authorized Halcyon Dealer.
• Air Control Vane (ACV) offers a second diver adjustment for the ability to fine-tune breathing. The ACV uses vacuum assist technology to reduce work of breathing and increase diver comfort. This level of refinement is available on all Halcyon second stages. ACV in “dive” position gives powerful breathing support while ACV in “Halcyon” position helps prevent free flows; this can be helpful on the surface, when diving in currents, while scootering, or when the Halo is used as a backup regulator.
• Comfort mouthpiece is standard on every second stage to reduce jaw fatigue and mouth irritation. This long lasting mouthpiece requires only a minimum effort to hold comfortably in place. In combination with the freedom of head movement provided by Halcyon’s primary long hose, you will enjoy dives free from the jaw fatigue common with certain mouthpieces and/or poorly balanced hose routing.

Aura second stage regulators provide a simple, compact design that makes breathing under water feel completely natural. This high quality second stage delivers air in a smooth, dependable fashion. Halcyon’s Aura second stage comes with a single adjustment control and a pre-set inhalation effort that suits most common diving situations; this feature makes it a common selection as a backup regulator. The Aura is an ideal regulator for divers who want a simple, ready to dive regulator; it is also a common choice for training systems and rental units.

• Classic downstream valve style regulators have an impressive safety record and are commonly accepted as an extremely reliable design. Part of their reliability results because the downstream valve opens in the same direction as the incoming airflow; a spring counteracts the force of the incoming air. In this design a small inhalation is required to overcome the spring tension and open the valve. This spring pressure is adjusted at the factory and allows easy breathing and consistent performance. Your Authorized Halcyon Service Technician can make any desired adjustments.
• Air Control Vane (ACV) offers a second diver adjustment for the ability to fine-tune breathing. The ACV uses vacuum assist technology to reduce work of breathing and increase diver comfort. This level of refinement is available on all Halcyon second stages. ACV in “dive” position gives powerful breathing support while ACV in “Halcyon” position helps prevent free flows; this can be helpful on the surface, when diving in currents, while scootering, or when the Aura is used as a backup regulator.
• Comfort mouthpiece is standard on every second stage to reduce jaw fatigue and mouth irritation. This long lasting mouthpiece requires only a minimum effort to hold comfortably in place. In combination with the freedom of head movement provided by Halcyon’s primary long hose, you will enjoy dives free from the jaw fatigue common with certain mouthpieces and/or poorly balanced hose routing.