Diving Regulator Jargon Explained
When purchasing a diving regulator, the technical terminology can seem overwhelming. However, you don’t need an advanced engineering degree to make an informed decision. This guide from Scubaexpress breaks down common regulator terms in a clear and understandable way, helping you determine what you need and what you don’t.
Terms like balanced, compensated, piston-controlled, sealed, VIVA, deflector, downstream, DIN, INT—what do they mean? Are they good or bad? Do you need them? We clarify these terms so you can confidently choose the right regulator for your diving needs.
What is a Diving Regulator?
When Jacques-Yves Cousteau and Émile Gagnan invented the independent air supply system, they called it the Aqualung. Today, it is most commonly referred to as a diving regulator or simply a reg.
The official term for the complete setup is SCUBA (Self-Contained Underwater Breathing Apparatus). In some cases, the second stage is called a demand valve because it supplies air only when the diver inhales. However, the entire regulator system should not be called a demand valve—only the second stage has this function.
For a deeper understanding of how a regulator works, refer to our guide: “What a Regulator Consists of and How it Works.”
Main Regulator vs. Reserve Regulator
Sometimes, divers refer to the second stage as the main regulator and the octopus (alternate air source) as the reserve regulator. However, this can be confusing because many divers think of the entire system when hearing the term “regulator.” To avoid confusion, it’s best to refer to these components by their correct names:
- Second Stage (the main breathing component)
- Octopus or Alternate Air Source (the backup for emergencies)
Open Circuit vs. Closed Circuit Systems
A traditional diving regulator is an open-circuit system, meaning that when you exhale, the air escapes into the water. However, closed-circuit rebreathers (CCR) and semi-closed systems (SCR) recycle part or all of the exhaled air, extending dive times and reducing gas consumption. These rebreathers are more complex and typically used by advanced or technical divers.
Diving Regulator Components
First Stage – The Heart of the Regulator
The first stage attaches directly to the dive tank valve and reduces the high-pressure air from the tank to an intermediate pressure before delivering it to the second stage.
Second Stage – Your Direct Air Supply
The second stage is connected to the first stage by a low-pressure hose. It further reduces the intermediate pressure air to ambient pressure, making it breathable. This is the part of the regulator that you place in your mouth.
- The second stage is sometimes mistakenly called a mouthpiece. However, the mouthpiece is actually just the soft silicone section attached to the second stage that you bite down on.
Octopus – Your Backup Air Source
The octopus, also known as the alternate air source, is a backup second stage used in emergencies. It is usually brightly colored (yellow or orange) for easy visibility.
Some divers mistakenly refer to the entire regulator system as an octopus, but this term only applies to the emergency backup regulator.
Pressure Gauge – Monitoring Your Air Supply
The pressure gauge (also called a finimeter) is a submersible instrument connected to the first stage via a high-pressure hose. It shows the current pressure inside your tank, allowing you to monitor your remaining air supply.
Inflator Hose – Controlling Buoyancy
The inflator hose connects the regulator to your Buoyancy Control Device (BCD) via a low-pressure port. It allows you to add air to the BCD for buoyancy control.
Final Thoughts
Understanding diving regulator terminology doesn’t have to be complicated. At Scubaexpress, we make it easy to find the right equipment by explaining the essentials in a straightforward way. For more in-depth information, check out our guides on choosing the right regulator and understanding regulator technology.
With the right knowledge, you can select a regulator system that fits your diving style, ensuring safety, comfort, and reliability underwater.
Leave a comment