Air is the single most important thing to a diver when scuba diving. Most recreational divers aren’t concerned with how or even when their scuba tanks get filled as long as they have them before a dive. While that’s all well and good for the holiday scuba diver that rents, for dive professionals and dive shops, scuba tank air compressors are crucial pieces of scuba equipment they can’t do without. Today, a lot of serious scuba diving individuals opt to have their own small and portable scuba compressor for their diving needs.
Imagine being able to fill up your scuba tank whenever you want, not having to wait in line at dive shops, and being able to dive whenever and wherever you want. Sounds nice, doesn’t it? While scuba tank compressors offer sheer convenience, they are not just a one-time investment. This piece of equipment is expensive and the running costs just to keep your system maintained and working properly can run high.
But if you’re determined to search the market for a good one, you can start by understanding its distinctions, how it works, and how you can choose the right one for your needs.
What Makes Scuba Air Compressors Different?
Scuba compressors are high-pressure air compressor systems that are designed to fill tanks that divers use for breathing underwater. They’re the same type of compressors used to provide air supply for firefighters as well as for oxygen tanks in hospitals. The differences between this type of compressor and standard compressors used for other purposes are mainly the pressure and resulting quality of the air it compresses.
Scuba tanks typically need to be filled at very high pressure (about 3,000 psi). Using a regular air compressor would only be able to provide a fraction of the air that scuba compressors can. Secondly, the scuba compressors have filters that are designed to purify the air that goes through them and fills the tank. They remove moisture, oil, and other contaminants by passing it through a series of moisture separators and filters.
After the moisture has been removed, the air passes through activated carbon filters, where carbon monoxide is rendered harmless and other hydrocarbons are removed.
The air filtering feature is extremely important because, unlike other purposes that standard compressors are used for, scuba compressors are used to fill tanks with clean breathable air that divers’ lives depend on. Unfiltered or contaminated air could have serious health consequences and even cause death, which is also why the maintenance of scuba compressors is also important.
How Do Scuba Air Compressors Work?
We won’t go into the nitty-gritty details on the inner workings of an air compressor, but here’s a brief description of how a scuba compressor works.
The First Stage
The first stage of the compressor will pull in air through an intake filter and compress it to around 100 to 140 psi as it pushes it out. During this process though, it heats up quite a bit, so an intercooler or coil will help dissipate the heat before passing the air to the second stage.
The Second Stage
The air that has been compressed to around 140 psi and cooled in the first stage will then go into the second stage, where the air is further compressed to around 800 to 1,000 psi. After the second stage, there’s also an intercooler that will cool the air again before it goes to a moisture separator and then to the third stage.
The Third Stage
The third stage further compresses the air to as much as 5,000 psi. From this stage, we go through another intercooler coil and another moisture separator. After which, there may be additional filters or filters that are mounted separately from the pump.
The Last Stage
Lastly, there is a back pressure valve, which is normally set between 2,700 and 3,300 psi. The back valve will force the compressor to run balanced and affect how the filtration works.
Factors to Consider When Buying a Scuba Compressor
Let’s take a look at the factors that need to be considered when buying a portable scuba compressor for the average recreational diver.
Type of Compressor
There are essentially two types of portable scuba tank compressors: electric and gas. Electric motor compressors are more commonly used and preferred, but it’s important that it is kept in a location that is wired properly. Electric motors also come in single phase or dual phase electrical systems. Smaller compressors typically require 220-240 volt electrical systems.
Low vs High Pressure
Low-pressure compressors are lightweight and are used in cases of surface supplied diving. The compressor is fitted in a flotation ring on the surface and supplies air to divers underwater through a hose.
On the other hand, high-pressure compressors compress air from 3,200 to 5,000 psi. They are commonly used by dive shops and even in commercial diving to fill scuba tanks. They are heavier and bulkier than low-pressure ones but are definitely better for filling tanks.
Maximum Pressure
Consider the maximum pressure of the compressor before you purchase it. The compressor’s capacity should be in proportion with your tank size. A small tank may not be able to handle a high-pressure compressor while a low-pressure model may not sufficiently compress air in a large tank.
Filtration
The filtration needed depends on the type of compressor and motor used. Gas compressors require more filtration to get rid of the carbon monoxide that comes from the motor exhaust. On top of that, if it’s an oil lubricated compressor, then you’ll need even more filtration to get rid of the oil/hydrocarbons in the air.
The filter systems rarely come with the compressor itself and often has to be bought separately. Ascertain whether the compressor complies with international breathing air standards.
Heat and Noise
All compressors generate considerable amounts of heat and can also be very noisy—more than 100 decibels, in some cases. These two factors lead many dive shops to set up a “compressor room” where the heat can be vented and the noise contained, while air is distributed to where it is needed through long hoses or piping.
If you don’t have the luxury of space, you may want to make arrangements to get an enclosure for the compressor to reduce noise levels. Alternatively, you can choose a quieter type of compressor. For the heat factor, the space or enclosure the dive compressor is kept in should be well ventilated and allow ample airflow.
Do Your Research Before Buying a Scuba Compressor
Scuba air compressors are very expensive and can require a lot of maintenance and upkeep to keep them running smoothly. It’s a real commitment to own and run your own compressor. Therefore, it’s important to know the ins and outs of the compressor you buy and have basic mechanical abilities to safely operate your compressor.
If you’re ready to take on the expense and responsibility, take your time to do your research on different models and manufacturers. Ask the manufacturer or authorized dealer about the maintenance, cost of spares, rebuild kits, and other related information, and have them answer any questions you might have before making the purchase.
