Saturation Diving Compressors

Reavell - Reliable Under Pressure

Reavell’s experience of 100+ years in the marine and offshore industry allows it to offer focused solutions. This includes product life-cycle support, compact design, easy maintenance, low TCO, long-term reliability and much more. Our bare blocks and packages are certified for marine and offshore diving applications, covering DNV, Lloyds and Bureau Veritas. We follow all safety standards, making Reavell solutions the low-risk selection option.

What is Saturation Diving?

Saturation diving (also known as saturated diving) subjects the diver to be underwater at constant pressure for extended periods of time. This type of diving is typically used to perform underwater work.

Saturation diving is used to extend the duration of underwater work or exploration by eliminating the need for repetitive decompression stops. This is achieved by having the divers live and work at a constant pressure in typically several atmospheres (ATA). The divers stay in this state for an extended period; typically several weeks. The divers' blood and tissues become saturated with dissolved gasses; mainly a combination of oxygen and helium (Heliox). Heliox is used to reduce the risk of decompression sickness (DCS).

During saturation diving, the divers live in a pressurized environment, such as a saturation habitat or a diving bell. These are connected to the surface by an umbilical. The saturation habitat provides comfortable and safe living quarters and a working environment for the saturation divers. It allows them to decompress gradually over a long period of time instead of making repetitive decompression stops during their dive. Saturation diving is commonly used in the deep sea, by scientific and commercial divers. Here, the work or exploration requires extended periods of time underwater, and the risk of decompression sickness is high. It is also used in the oil and gas industry for the inspection, maintenance, and repair of offshore structures and pipelines.

What Equipment is used for Saturation Diving?

The following specialized equipment is used for a saturation system.

  • Diving Bell: A chamber used to transport divers to and from the work site. It provides a pressurized environment for them to live and work in.
  • Saturation Habitat: A larger pressurized chamber where the divers can live and work for extended periods of time.
  • Diving Suit: A specialized suit designed to protect the diver from the cold and provide life support.
  • Breathing Gas Supply: This is typically a mixture of helium and oxygen (Heliox) used to sustain the diver's life underwater.
  • Umbilical: A system of hoses and cables that connect the saturation habitat or diving bell to the surface. It provides communications, life support, and decompression gas.
  • Decompression Chamber: A chamber used to decompress the divers gradually after they return to the surface.
  • Dive Support Vessel: A surface vessel equipped with the necessary equipment and personnel to support the diving operation.
  • Trained and Certified Divers: Divers who have received specialized training and certification for saturation diving. They have the necessary skills and knowledge to perform the dive safely.

The Importance of Heliox Gas

There are a variety of gasses used in deep-sea diving but the most common in saturation diving is Heliox.

Heliox is a mixture of helium and oxygen and it is very important for saturation diving. It is used in saturation diving because its composition is less dense and has a lower narcotic effect than air. This makes it a safer and more practical option for diving at greater depths.

At depths greater than 500 feet (150 meters), the pressure of nitrogen in air becomes problematic, as it can cause nitrogen narcosis. This is a form of impaired judgment and motor control that can be dangerous for divers. Helium, being a lighter gas than nitrogen, does not cause narcosis at the same depths. It can be used to reduce the risk of nitrogen narcosis for divers.

In saturation diving, a breathing gas mixture of heliox is used to reduce the risk of decompression sickness and nitrogen narcosis. It also provides a safe and reliable supply of diver breathing gas. The use of heliox also helps to reduce the size and complexity of the decompression obligation. This makes it easier and more practical for the divers to manage their exposure to nitrogen and other diving related hazards.

Gas composition based on diving depth and stay time:


Gas Composition

Diving Depth and Relative Time Spent

Air (21% 02& 79% N2)

40M & short time

Nitrox (32% O2& 68% N2)

40M & longer time

Trimix (18% O2, 37% N2& 45% He)

60M & longer time

Heliox – (20% O2& 80% He)

300m & longer time


Challenges Faced by Diving Businesses

  • Cost: Saturation diving is a complex and specialized type of diving that requires significant investment in specialized equipment. This includes infrastructure, and training, which can be expensive and challenging for diving companies to manage.
  • Safety: Saturation diving is a high-risk activity. It requires careful planning, execution, and management to ensure the safety of the divers. Divers are exposed to a range of physical and environmental hazards. This includes decompression sickness, nitrogen narcosis, and the effects of high pressure.
  • Logistics: Saturation diving operations often take place in remote and inhospitable locations. These can pose significant logistical challenges, including the transportation of equipment and personnel and the supply of resources. In addition, the management of waste and other environmental issues greatly impact saturation diving.
  • Regulation: The saturation diving industry is heavily regulated. Diving companies must comply with a range of international, national, and local safety and environmental regulations. These can often be time consuming and costly.

Despite these challenges, saturation diving remains a critical component of many underwater construction, repair, and maintenance projects. It offers a range of opportunities for diving companies to grow and expand their businesses. To be successful in the saturation diving business, diving companies must invest in the right equipment, training, and infrastructure. They must work closely with regulators, clients, and other stakeholders to ensure the safety and success of their operations


The Benefits of Reavell High Pressure Compressors for Saturation Diving

Reavell is a renowned brand in the marine and offshore arena. They offer an extensive range of high-pressure reciprocating compressors that are tailored and made for saturation diving. The Reavell range offers:
• Volumetric flow from ~40 m3/hr to ~158 m3/hr with a delivery pressure range from 200 to 350 barg.
• Gramophone finish on piston surface compliments the plateau honed bore, to ensure optimum lubricant control.
• Low lift combined suction/delivery valves specifically for low-density inert gas operation.
• Integrated unloading and condensate drain block
• Marine-type (captive) anti-vibration mounts

 As a complete package solution provider, our packages are equipped with additional features such as:

• Gas inlet O2 monitoring / trip (O2 content max allowed is 21%)
• Carbon monoxide monitoring/trip
• Breathing air filtration systems
• Complete plug-and-play packages design approved and type approval for our compressor blocks
• Available in vertical and horizontal configurations to meet footprint requirements
Reavell has a wide range of customers that operate globally. These are established companies active in the defence and commercial markets. Reavell devices and services have helped our partners grow their businesses with assured confidence and reliability.  

Diving Systems You Can Rely On

Reavell is a trusted name in marine and offshore compressor supply, a name built on over 120 years of supplying the most reliable compressors on the market. And we have developed our market leading range of marine compressors, world renowned for their reliability and maintainability, specifically for the saturation diving market. For example, with our sub-atmospheric inlet pressure systems you can be sure that not only are your compressors designed specifically with your application in mind, but they will offer maximum reliability.

What’s more, our focus on ensuring maximum maintainability and ease of integration, along with our dedication to the highest quality service and support, ensure our compressors are a safe and dependable source of breathing gas.

Reavell H5437 Heliox breathing gas compressor
Reavell H5437 Heliox breathing gas compressor

Primary Sectors Served

  • Rescue and Recovery
  • Diving
  • Defence
  • Marine/Offshore