Scuba Compressors how do they put air in my tank?

Scuba compressors

What is that noise? Have you ever been in a dive shop and been unable to hear anything? You want to talk to the shop owner, but there’s a deafening roar that can only be described as the sound of an air compressor.

These things are huge; they’re monsters.

In fact, dive shops will sometimes give these behemoths their own room (mostly in an attempt to deaden the sound).

But how do these things work?

What do they do?

How do they squeeze air from the atmosphere into your tank at the outrageous pressure of 3,000 pounds per square inch (210 bar)?

Here’s the story on the noisy beast in the back of your local dive shop.

Scuba Compressors – Compression

Compression is the first step in putting air from the atmosphere into your tank. In a dive shop, compressors are usually driven by electricity, though they can also be driven by gas or diesel.

Since the air is compressed by an engine, oil is necessary to keep the engine parts lubricated.

Only food grade oil is used to prevent excess impurities from getting into the air supply. From here, the air goes to filtration.

Scuba Compressors - Filtration

All compressed air needs to be filtered no matter how pure you think it is.

A small trace of carbon monoxide can be harmless on the surface, but when you breathe it at depth it can be fatal.

To prevent any impurities from reaching your tank, compressed air goes through a number of mechanical and chemical filtration processes to purify it. Once the air is purified, it moves on to the next stage.

Scuba Compressors - Drying

After the air is filtered, it goes through a drying process to make sure that no moisture makes it to your scuba tank.

This can be accomplished in several ways, but it usually happens with the use of air dryers and rapid expansion of the compressed air. The drying process usually results in some loss of air and a lot of water drainage.

Scuba Compressors - Storage

It would take forever if you needed to go through this whole process just to fill a single 80 cubic foot cylinder, so scuba compressors usually fill several very large high pressure cylinders.

The air is then stored until the dive operator needs to fill your tank.

Scuba Compressors - Distribution

There needs to be a way to get the air from the high pressure cylinders to your cylinder without blowing the pressure release valve on your tank.

That’s what the distribution portion of the air compressor does. This part of the compressor usually consists of several knobs and gauges designed to help the dive operator slowly fill your tank.

If your tank were to fill too quickly it would get very hot and the air would expand. After the tank cools you may find that your 3,000 psi (210 bar) tank has only 2,300 psi (160 bar) in it.

Some of the best scuba compressors are made by Bauer.

One last word about Scuba Compressors and tank fill stations:

The most dangerous time to be around a scuba tank is when it’s being filled. Always stay clear of the fill station when tanks are being filled up.

Your life isn’t worth risking just to watch some tanks fill with air.

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