Once diving becomes a serious hobby, you might be interested in buying your own compressor for filling your tanks. There is nothing wrong with dive shops, but there’s nothing like being able to fill up your tank wherever you are.
Since the air in your tank is a matter of life or death, the air compressor for your scuba tank needs to provide you with clean pressurized air.
When you choose a scuba air tank compressor, it needs to be specifically made for diving. Unless the compressor delivers clean breathing air at high pressures, you risk injury or death when you dive.
This guide will help you understand how a compressor works, what makes a scuba air compressor different from a normal one, and what to look for when buying one.
Many companies build compressors, but only a few manufacture breathing air compressors for scuba diving. We recommend the following:
Best Scuba Air Compressors
1. Alkin W32 Silent Canopy Scuba – High-Quality Breathing Air Compressor
Alkin has been in the high-pressure compressors market since 1990. Along with a line of scuba breathing air compressors, they also manufacture compressors for paintball, air guns, and fire and rescue operations.
The scuba line of compressors falls into two groups—Canopy and Mariner.
The W32, W3, and W4 Silent Canopy are larger units best suited for filling stations. The W32 is the smallest unit, but at 640 pounds, there’s nothing portable about it.
Alkin has two portable air compressors—the W31 and W32 Mariner.
Alkin W32 Mariner
The W32 Mariner, at 20 inches wide, 44-53 long, and 27-32 high, is on the large side of portable scuba compressors and on the heavy side. The lightest model weighs 364 pounds, making the unit better suited for use on a boat.
You can purchase a gas or electric power, and the power range is from 7.5 to 13 horsepower. All models have a max psi of 5,000, and the fill rate is either 250 or 300 liter per minute.
Most importantly, air quality is Grade E and D.
- Safety valves
- Oil pressure switch and gauge
- Overload protection for the electric motor model
- Two filling hoses
- P41 purifier with refillable purifier element
- 2nd and 3rd stage water condensate and oil separator
An automatic start and stop is an optional feature; however, it should be a standard feature with a scuba compressor.
Alkin 31W Mariner
For true portability, check out the Mariner 31W. It is a compact 17 by 32 by a 20-inch breathing air compressor (the gasoline models are 41 inches long). Not only does it weigh 143 pounds, but the 31W also has a vertical option that comes with wheels, allowing for greater mobility.
As with the 32W, the 31W has similar key features:
- P21 purifier
- 2nd and 3rd stage water condenser and oil separators
- Safety valves for each stage
- Overload protection for electric motor
- Grade E or D air quality
The 31W has only one filing hose, as one would expect from a genuinely portable compressor. The hose comes with necessary yokes, valves, adapters, and pressure gauges.
Again, Alkin makes the automatic start, and stop is an optional feature?
Still, if you are looking for a portable, relatively lightweight breathing air compressor, the Alkin W31 Mariner is a good option. The starting price will be around $3,000.
2. Max-Air 35 – Small Scuba Air Compressor
The Max-Air 35 is a reliable portable compressor. The GS has a 6 hp Subaru engine, and the STD model is electric driven. The GS weighs 85 pounds, and the STD is a slightly heavier 100 pounds. Both fill an 80 cubic foot tank in 22 minutes.
If you plan to use the GS on a boat, you will need an 8kW generator. The compressors come with standard filtration systems so that you get Grade E quality air.
- These are loud compressors, rated at 87 dB at 10 yards.
- The electric models do not come with plugs.
Expect to pay around $3,000 for these models.
3. Nardi Atlantic Series
There are two models in the Atlantic Series, the Atlantic 60 and Atlantic 100.
The 60 has a mono-phase motor, has a fill rate of 60 liters per minute, and weighs 87 pounds. Along with being the lightest of the Atlantic models, it is also the quietest, running at 76 dBA.
The 100 Series compressors are not much heavier or louder, however. The Atlantic 100 comes in a single-phase, three-phase, or gasoline model. Each weighs 93 pounds. The gasoline model is the loudest, with a decibel level of 84 dBA, while the other two 100s are 5 dBAs quieter.
The fill rate for the Atlantic P 60 is 33 minutes for a 10-liter tank, while the Atlantic 100s bring the fill rate down to 20 minutes.
The design simplicity of the filling valves means filling a tank is straightforward. The filtration system is adequate for filling diving cylinders with Grade E air.
The Nardi Atlantic line is more expensive than the Alkin. Expect to pay close to $4,000 for a new model.
When purchasing this model, consider adding the optional hour meter so you know when it’s time to get a new filter. If you want to lighten your load, add a trolley system (wheels and handle).
Nardi Pacific Series
Although the Nardi Pacific scuba air breathing compressors have extremely fast filling time (under 6 minutes for the Pacific P 35), their 300+ pound weight keeps them from being truly portable.
Bauer Scuba Breathing Air Compressors
German-made Bauer is considered by most divers to make the highest-quality compressors for filling your scuba tanks. Bauer has 70 years of experience designing and manufacturing high-pressure compressors. Bauer also has product lines for military, technology, oil and gas, and plastics technology along with breathing air products.
4. Dive Mate
Because they are designed and built in Germany, all portable models—the Dive Mate, Junior II, and Oceanus—have diesel, electric, and gasoline-powered models.
The Dive Mate model is rather heavy—at either 136 pounds for the Size 8 model or 181 pounds for the size 10. However, both sit on a wheeled frame so that you can roll it in place.
These scuba compressors have several standard features that the other compressors either do not have or as optional features, including
- Vibration isolators (for quieter operation)
- High-temperature switch
- Visual indicators for moisture and CO
- Hour meter
The fill rate is 238 liters per minute for the Model 8 and 275 liters per minute for the Model 10. The Model 8 is rated to 5,000 psi, while the Model 10 has an impressive 6,000 psi.
Bauer takes quality breathing air seriously and has developed a patented filter that uses UVC light to destroy pathogens before they can enter the scuba tank. They are rated for 2,000 hours of use. These filters must be retrofitted on older Bauer models.
Junior II and Oceanus—True Portability
If you want true portability, these two models are the lightest true scuba breathing air models. The Junior model weighs between 40 and 75 pounds, while the Oceanus is four pounds heavier.
Both models come in a variety of packages, depending on the fuel source. All are 3 stage compressors and have a standard Bauer filtration system. The Junior models have a lower fill rate (in the 82 to 122 range). All the Oceanus models have a fill rate of 139 liters per minute and can fill two cylinders.
Bauer’s Junior II and Oceanus are the only compressors that include a yacht package. Because of the large oil sump, these compressors have the highest inclination at 30 degrees.
Bauer’s do not come cheap. Expect to pay around $6,500 for the Oceanus and over $10,000 for the yacht packages. The Junior II is comparatively a bargain at approximately $5,000.
Mini-Dive—the Little Compressor for the Little Tank
Mini-Dive is a French company that has developed a unique diving system. Instead of a large tank and training and certification, anyone can use the mini-dive system. That’s because the tank’s capacity ranges from 10 minutes to 20 minutes of breathing time, depending on the size of your tank.
The maximum authorized depth is 10 yards even though the tank is built to work at five times that. The tanks can be filled with a hand pump, or you can use the Mini-Drive compressor.
The Mini-Drive compressor is a 220-volt compressor designed specifically to fill the Mini-Drive tanks. The fill time is 7 minutes. The Mini-Drive compressor has a simple filtration system, and Mini Dive recommends it be replaced after every fill-up.
Expect to pay around $1500 for the entire set up—tank, harness, and compressor. Note: do not be fooled by the price–this compressor will not fill full-sized tanks.
Why You Should Buy a Compressor for Your Scuba Tank
As you transition from being an occasional, weekend diver to a serious one, you might want to buy an air compressor. The two most important reasons to buy a scuba air compressor is portability and saving time.
- If you are at a dive site and want to take a lunch break before your afternoon dives, you don’t need to hike back to the shop to refill your tanks.
- The dive site is not close to a shop.
- You and a couple of your diving buddies want to pool your resources and have a portable compressor.
A beginning diver might want to make sure they will stick with it long enough to offset the investment of a scuba compressor. When you finally decide to get a compressor, make sure it is designed for diving.
What to Look for in a Scuba Air Compressor
Here are several considerations to keep in mind as you begin your quest for a scuba air compressor:
- Electric or gas. If you want a more portable compressor, then gas might be the way to go. Although gas compressors are more convenient, there’s a chance of having fumes enter your tank when you use them.
- Pressure. A low-pressure compressor is adequate for diving up to fifty feet, but professional divers going over that depth should purchase a full-strength, high-pressure air compressor.
- Size of your tank. Your tank must be able to handle the pressure levels of your compressor.
- Filtration. Gas and oil-lubricated compressors require filter systems. You will often need to buy these systems separately.
- Weight. A heavier compressor will be less portable but will have more power than a light one.
- Fill time. A compressor with a fill time of 3.5 cubic feet per minute will fill an 80 cubic-feet tank in just under half an hour.
- Air quality. A compressor should put out Grade E breathing air.
Also, some compressors are noisier than others. Generators also let off a lot of heat, so the area where you will be using one needs to be adequately ventilated.
Can I Use a Regular Air Compressor to fill My Tanks?
You should only use an air compressor designed to fill scuba air tanks. Divers rely on the air to breathe, so a compressor needs to do two things—provide breathable oxygen at high pressure.
The Need to Filter the Air
To provide the diver with breathable air, scuba compressors rely on a filtration system that does the following
Remove moisture and oil in the air. Water needs to be removed from the air because a diver cannot breathe it. Also, water cannot be compressed, and a scuba tank needs to be highly pressurized. A separate issue is that water can also cause the tank to rust.
Eliminate poisonous gas. The compressor must remove toxic carbon monoxide and bring carbon dioxide to safe levels. The filtration system oxidizes carbon monoxide (CO) and converts it into CO2. Activated carbon filters and molecular sieves in the system are used to reduce the level of carbon dioxide.
Most air compressors for scuba tanks use a combination of an air dryer, water traps, and filters to remove moisture and deliver breathable air. The filtration system is complex–check out the diagram of a scuba air compressor’s filtration system to see how the different parts work together.
The Need to Pressurize the Air
A scuba tank needs to be filled to around 3,000 psi (pressure per square inch), which a regular compressor cannot do. The high pressure is required so that a scuba diver can expand their lungs to breathe underwater.
Remember that any gas moves from a high to a low-pressure space. When you blow into a balloon, it fills up because the pressure inside it is higher than the air pressure around it. Now imagine that the balloon is in a box. You would be able to blow the balloon until it filled the box and no more because the pressure you can exert is less than what is needed to break the box.
Even though it is not a solid, ocean water exerts more pressure than the atmosphere, and the pressure increases as depth increases. To compensate, the air coming from the diving tanks needs to be higher than the pressure of the water. Otherwise, a diver will not be able to breathe in air.
Higher pressure in a tank gives the diver more time to be underwater. A recreational tank that holds 80 cubic feet of air at 3000 psi holds the amount of air that would fit into an eight by ten room.
For those two reasons, diving tanks need to be filled with a scuba air compressor.
How Does a Scuba Air Compressor Work?
Most compressors compress air in stages. In the first stage, the air is pulled through an intake filter to 100-150 psi. Because the air heats up dramatically, it needs to be cooled before the second stage.
In the second stage, the air is compressed close to 1,000 psi. Again, the air is cooled. Then it typically passes through a moisture separator. The third stage increases the psi higher than 3,000 psi. Additional moisture separators or filters may be used in this stage.
For the final stage, a back-pressure valve is used to lower the psi to 3,000.
Frequently Asked Questions
How Do You Fill a Scuba Tank?
Let’s assume that you have had your tank hydrostatically tested within the last 3 to 5 years. Further, let’s assume your tank has been visually inspected by a dive shop within the previous year. If you have not done those two, you should not fill a scuba tank.
Also, you should know the tank’s psi rating so that you don’t go over it.
- Release extra air from the tank.
- Do a quick visual inspection for any cracks.
- Give it a shake. If you hear rattling or sloshing water, do not use the tank.
- Inspect the oil ring to make sure it is not cracked.
- Make sure the tank’s valve is clean.
- Attach the Yoke to the tank.
- As you fill, monitor gauges, and be prepared to shut off the compressor if the auto shut off malfunctions.
How Much Does It Cost to Fill a Scuba Tank?
Most dive shops charge around $5 to fill up a tank. People don’t buy scuba air compressors to save money but to save time. Of course, some say time is money.
Can I Use an Oxygen Tank for Scuba Diving?
No, oxygen tanks should not be used for scuba diving. Pure oxygen at high pressures is toxic. Scuba tanks are filled with the same air that we breathe, which has around 20% oxygen. Helium is added to scuba tanks when divers go to extreme depths. This is to decrease dangers from nitrogen.
Scuba compressors are not cheap. You are buying a specialized machine that needs to provide highly compressed breathable air. Do not go cheap with a scuba air compressor—your life is not worth it.