How to Choose Your Perfect Scuba Regulator

Scuba regulators form the foundation of the scuba systems, linking everything together with you. They consist of two parts: the first stage and second stage. The first stage attaches onto your scuba tank and has connection ports holes. There are usually five or more, at least one high pressure port and four low pressure ports. For most scuba kits, these hoses are a low pressure inflator hose (LPI), submersible pressure gauge (SPG) and two second stages: your primary second stage and alternate second stage called an octopus.

During all PADI courses (besides some TecRec courses), you will use “open circuit” scuba regulators. This means that when you exhale, the air you breathe out is released out of the scuba system. This can be seen in the form of bubbles coming out underwater. Scuba regulators are also known as demand valves or demand regulators as they supply air “on demand” as you breathe in, so air isn’t continuously flowing. Ultimately the scuba regulator provides you air from your scuba tank for you to breathe safely underwater.

As mentioned, the scuba regulator delivers air from the tank. But why can’t we breathe from an open hose connected between the tank and our mouth? There are two reasons for this:

Even though a scuba regulator serves a very simple purpose, investing in the right regulator will provide the best experience for the type of diving you do. It’ll also be reliable, require minimal servicing and overall feel more comfortable. Each part (first stage and second stage) can either be sold separately or as a set with the additional hoses (SPG and inflator hose). So there are many ways to customise your scuba regulator to best suit you.

Nowadays, most scuba regulators are balanced meaning they have ‘balanced valves’. However, there are still a few low-end models that are not. Having a first stage with a ‘balanced valve’ helps keep the breathing performance of the first stage consistent throughout the dive. To explain this, as you use up the air in your scuba tank, the pressure in the scuba cylinder decreases which would cause less and less air flow into the regulator (if it is unbalanced). This makes breathing much more harder towards the end of the dive. But the ‘balanced valve’ in balanced regulators works in a way that your breathing effort isn’t affected by this and remains the same throughout the dive.

The number and location of ports vary with different models. Check that the first stage has enough ports to attach all your required hoses (note that dry suits add an extra low pressure hose) and that they are positioned to match where they go on your buoyancy control device (BCD). Some first stages have a swivel making it easier to direct the hoses towards the position you want them. Most higher end regulators provide at least four low pressure ports that deliver air at intermediate (low) pressure (for your LPI, primary and secondary second stages) and one or two high pressure ports (for your SPG). To be able to identify high and low pressure ports, there are some manufacturing standards. In North America and Asia, they are the same size, though high pressure ports are marked with ‘HP’. In Europe, some models have different sized ports to differentiate low to high pressure ports.

The first stage of the scuba regulator converts air from high pressure to intermediate pressure providing a stable supply of gas for breathing and other applications. In a scuba regulator, intermediate pressure is controlled by the surrounding ‘ambient’ pressure pushing onto a metal spring called a ‘bias spring’. This bias spring applies a constant force towards the valve allowing for intermediate pressure to be released. In an ‘unsealed’ scuba regulator this is simply done by allowing the surrounding water to enter and push onto the valve mechanism. A regulator that is environmentally sealed however contains a watertight pressure-sensitive barrier on the base of the first stage containing a silicone/alcohol based fluid. When the surrounding water pushes on this, ambient pressure is transmitted.

There are two main advantages of an environmentally sealed regulator:

The only disadvantage is that it does come at an extra cost so expect to pay a bit more for this.

There are two types of connector systems, the DIN (Deutsches Institut für Normung) and the Yoke.

Yoke connectors are mainly used for recreational diving though the DIN is much more popular across all diving in Europe and is the standard connector used in technical diving. The DIN connector also has two types, the 5 threaded version which is used for pressures up to about 200 bar/ 3000 psi, and a seven thread version to withstand pressures higher than this. DIN regulators have their own o-ring, which means you must independently maintain it to ensure a good seal with the scuba tank. With Yoke regulators, the o-ring is located in the scuba tank itself. DIN to Yoke adapters are also widely available so it is easy to use a DIN regulator with a Yoke scuba tank if required. Unfortunately, there are no adapters for the other way round. The only way to convert a Yoke connector to a DIN is to get it done by a professional. Therefore DIN regulators are normally recommended, especially for professional divers because of their adaptability.

These are two types of mechanisms that can be found in the first stage. They control the opening and closing of the valve inside, helping to deliver the air at the correct pressures to each hose. The differences between these two are how they practically work, one is no better than the other. However there are a few advantages of each:

Second stages are configured with a mouthpiece, a diaphragm controlled demand valve and an exhaust diaphragm. A standard second stage will have the diaphragm at the front (also identified as the purge button) and exhausts at the back. The demand valve operates when a diver inhales. This pushes the diaphragm onto a demand lever which opens up the valve and delivers air to the diver. On an exhale, air is released through the exhaust diaphragm in the form of bubbles to the side of the diver’s face. Demand valves are also downstream valves, meaning that air always flows from the tank towards the second stage, even when the second stage malfunctions.

Other configurations more uncommonly seen use something called a pilot valve. The smaller pilot valve opens the main valve offering a two stage system that offers greater airflow with less breathing effort. However they are much more complex to service and have a tendency to free flow. The diaphragm and purge button are located either on the side or bottom of the second stage.

When purchasing a pilot valve regulator, it is also important to ensure that it is fail-safe. This means that it has a downstream flow which opens the valve with the flow of air rather than upstream which opens against. Therefore when the regulator malfunctions, air continuously gets delivered (a freeflowing regulator) so you can still breathe from it to ascend safely to the surface. Definitely something to consider to promote your own safety.

Another feature in new higher end models are ‘balanced’ second stages. Unlike balancing the first stage, this doesn’t improve breathing performance but allows manufacturers to use premium materials which are more long-lasting and perform better.

In all second stages, you can change the tension of the valve making it easier/harder to open. Tuning it up makes the regulator easier to breathe from but more sensitive to free flow and detuning does the opposite. This can be adjusted internally by a technician but some second stages offer an external adjuster. This can be found as a knob on the side of the second stage which you can turn up or down. Having an external adjuster allows you to fine tune your own breathing resistance and ensures the tension of the valve remains optimal so that performance isn’t affected as your regulator ages.

This is an adjustable switch, also located on the side of the second stage and helps to reduce breathing resistance by redirecting the air flow. When this is turned on, this switch uses something called the venturi effect which creates ‘low pressure assistance’ making inhalation more easier. This makes dives much more comfortable as breathing requires less effort.

There are many features to consider between different models and types, but this doesn’t need to complicate your decision. Overall, the main points you need to think about when choosing the right regulator for you are:

Need some recommendations for your scuba regulator? Contact us for more information, we will gladly share some of our favourite models and have a conversation around purchasing equipment in general.