How Do Diving Regulators Work?

We all use them, but how many divers understand how they work? Diving regulators are not only impressive bits of technical kit, but also one of the first pieces of equipment a new diver will buy. Regardless of whether you're new to the diving scene or an experienced diver, if you're anything like us, you'll be curious about how these remarkable pieces of equipment work to keep us safe and breathing even at significant depths. Regulators have undergone many changes since the first demand regulator was made in 1864. Modern regulators are safer, lighter, and more robust, but many of the principles remain the same. So how do they work? Let's get into it.

Basic Principles of Diving Regulators

In a nutshell, your dive regulator reduces the pressure in your diving cylinder from 232 or 300 bar to a pressure suitable for breathing. It does this in two stages. The first stage attaches to your cylinder and reduces the pressure to around 10 Bar.

The second stage lowers the pressure further to an ambient pressure that is comfortable to breathe in any depth of water. It keeps the pressure different at <0.05 Bar, meaning you can breathe easily and safely, no matter how deep you're diving.

In Greater Depth

To understand how your diving regulator works, it's easiest to start from when you breathe in underwater. That means (counterintuitively) we should start from the second stage and work back to the diving cylinder.

How the second stage works

As you take a breath through your second stage, your lungs suck the air from the second stage chamber, reducing the pressure in the second stage. The water pressure outside pushes on the diaphragm (shown in orange in the image) just inside the front cover. It does this to balance the pressures between the two areas. This pushes on the Venturi lever (shown in red, named after the Venturi effect) and opens the valve, allowing air from the first stage to enter.

When enough air (and therefore pressure) has entered the second stage, the diaphragm is pushed down towards the front cover, closing the valve. This is what is known as a demand regulator. As you demand air, your regulator will give it to you. Conversely, there are positive pressure regulators that work slightly differently.

This design is brilliant, as it uses the ambient pressure of water to keep the pressure difference below 0.05 Bar at any depth. Although there are variations on this design, such as adding dial-a-breaths, this basic design is employed throughout all diving second stages.

How the first stage works (diaphragm)

So, how does the first stage work? In contrast to the second stage, there are a few different ways the first stage can be constructed. You may have heard terms such as balanced vs. unbalanced or piston vs. diaphragm. However, the main principle remains the same regardless of the construction and operates in a very similar way to the second stage.

As the valve opens on the second stage, air flows down your intermediate pressure hose. This causes the diaphragm (orange) to be pushed up by the water pressure, opening the valve (red) to allow air from the tank. When enough air has entered from the cylinder, the diaphragm is pushed down, and the valve closes.

Balanced vs. Unbalanced

The terms balanced and unbalanced crop up when talking about diving regulators, but what do they actually mean? Let's look at the picture of our first stage again:

Difference between balanced and unbalanced diving regulators

The difference between balanced and unbalanced first stages comes down to the design of the area behind the valve. In a balanced regulator, there is uniform pressure acting on the spring (green). The pressure on both sides of the valve is balanced regardless of the depth or cylinder pressure. In an unbalanced regulator, the pressure is not uniform. At greater depths or lower cylinder pressures, the regulator will struggle to regulate the pressure, resulting in more resistance through the second stage.

So why are there unbalanced first stages? They seem to have huge disadvantages compared with the balanced regulators. As with everything, it comes down to cost. It is far cheaper to manufacture unbalanced regulators, and so they cost less. If you are an entry-level diver, you may not be going to the depths where you notice the breathing resistance increase. Also, an increase in breathing resistance gives another indication that your cylinder is running out, so some divers prefer to have this warning alongside their SPG.

In truth, we see fewer and fewer unbalanced regulators for servicing. The cost has been brought down considerably on the balanced regulators, meaning that they are more accessible for newbie divers as an entry-level diving regulator. As divers upgrade their equipment, they tend to opt for a balanced regulator and trade in their unbalanced one with the manufacturer, meaning it gets removed from circulation.

Conclusion

This post was aimed at providing an overview of how diving regulators work. As you can see, they are incredible machines and quite intricate. This is why manufacturers recommend getting them serviced regularly, as any soft seal perishing or small debris entering the regulator can have disastrous consequences. Most manufacturers recommend servicing annually or after 40 dives, whichever comes first. Staying on top of servicing needs paves the way for safer, smoother dives and a more enjoyable time spent in the water.

Thoughts? Questions? Leave a comment below or email us at hello@obsequio.ltd—we'd love to hear from you!