I got this question the other day - what does it take to make scuba air? Good question actually. Making quality air is not difficult, but there are some real issues along the way you have to solve. I like to say it is part science and part art. To start from the beginning - when we opened the store, we understood all of the basics of making compressed air and even took a course in basic compressor maintenance and operation. But, what that told Carl and I was that we didn't know enough, that was when we went to the expert in Florida (which is saying a lot), Compressed Air Supply down in Broward County.
We had all the components for the system, a used military compressor, filter towers, banking bottles and a manifold, but needed expert advice. We knew that messing up the air is not an option, as this is life safety. Dick from Compressed Air set up us and built the system.
The system starts with the air intake. We use air from inside the store since cooler drier air makes for more efficient filters that last longer. At the intake, we use a small filter similar to a filter on a lawn mower. The air is drawn into the four stage compressor and each stage it goes through, the pressure is increased. After each stage, there is a separator. The separator's job is simply to take a high speed stream of air, hit it against a metal element which separates most of the oil and water out of the air stream (yes, oil, but more on that later). In the picture, there are two separators, one on each side of the radiator. All of the separators dump into a collector on the compressor and every 15 minutes, the compressor opens up the collector and blows it clear using air from the second stage. You can see the collector in the picture on the bottom just to the left of the gray electrical box. That is the sound you hear in the store when the compressor is running, a loud hissing noise as the air moves up through the muffler.
Once the air moves out of the compressor at working pressure (up to 4000 psi), it goes through the filter tower, starting with a very large separator that has to be manually emptied and then going into the filters. By now, the air is already low moisture and most of the oil should be removed. Oil gets into the air stream normally in a compressor when it goes around the piston rings and gets into the air. This is why we use food grade oil in the compressor, so that even if it did make it into the final product, it wouldn't be a major issue (it would taste VERY bad though).
Once in the filter tower, the air goes through layers of Hopcalite and activated charcoal. The Hopcalite scrubs carbon dioxide and carbon monoxide while the activate charcoal removes and residual taste. The air is then moved through the manifold, normally into the banking tanks and then into scuba tanks for breathing.
Every quarter, we test our air to make sure that it is safe. We send it to a national testing lab in Miami that does a number of test, including a spectrograph to test for stuff that shouldn't be there. It is important to note AIR SHOULD NEVER TASTE LIKE ANYTHING. If you get scuba air and it tastes like something, don't use it. Remember if we screw up and something gets past the filters, we have to assume that something is wrong and carbon monoxide may be making it past the filters as well. A lot of times, taste comes from something stored near the air intake. Most common culprits are paint products like thinner, gasoline and insecticides.
We had an issue where the carbon dioxide was raising earlier and our expert Dick figured out the issue for us. When the compressor was dumping the collector, the pressure on the filters was dropping, which was "breaking free" the carbon dioxide when the pressure came back up. We installed a one-way valve between the filters and the compressor and this solved the problem.
Filters need to be changed frequently to ensure good air quality. And the system needs to be drained everyday. We actually have a start up checklist for the compressor. Whenever I go diving, I always take a good look at the compressor and fill area. I have a new respect for clean, efficient and well maintained air systems.
If you ever want a tour of the air system, let me know. Greg
We had all the components for the system, a used military compressor, filter towers, banking bottles and a manifold, but needed expert advice. We knew that messing up the air is not an option, as this is life safety. Dick from Compressed Air set up us and built the system.
The system starts with the air intake. We use air from inside the store since cooler drier air makes for more efficient filters that last longer. At the intake, we use a small filter similar to a filter on a lawn mower. The air is drawn into the four stage compressor and each stage it goes through, the pressure is increased. After each stage, there is a separator. The separator's job is simply to take a high speed stream of air, hit it against a metal element which separates most of the oil and water out of the air stream (yes, oil, but more on that later). In the picture, there are two separators, one on each side of the radiator. All of the separators dump into a collector on the compressor and every 15 minutes, the compressor opens up the collector and blows it clear using air from the second stage. You can see the collector in the picture on the bottom just to the left of the gray electrical box. That is the sound you hear in the store when the compressor is running, a loud hissing noise as the air moves up through the muffler.
Once the air moves out of the compressor at working pressure (up to 4000 psi), it goes through the filter tower, starting with a very large separator that has to be manually emptied and then going into the filters. By now, the air is already low moisture and most of the oil should be removed. Oil gets into the air stream normally in a compressor when it goes around the piston rings and gets into the air. This is why we use food grade oil in the compressor, so that even if it did make it into the final product, it wouldn't be a major issue (it would taste VERY bad though).
Once in the filter tower, the air goes through layers of Hopcalite and activated charcoal. The Hopcalite scrubs carbon dioxide and carbon monoxide while the activate charcoal removes and residual taste. The air is then moved through the manifold, normally into the banking tanks and then into scuba tanks for breathing.
Every quarter, we test our air to make sure that it is safe. We send it to a national testing lab in Miami that does a number of test, including a spectrograph to test for stuff that shouldn't be there. It is important to note AIR SHOULD NEVER TASTE LIKE ANYTHING. If you get scuba air and it tastes like something, don't use it. Remember if we screw up and something gets past the filters, we have to assume that something is wrong and carbon monoxide may be making it past the filters as well. A lot of times, taste comes from something stored near the air intake. Most common culprits are paint products like thinner, gasoline and insecticides.
We had an issue where the carbon dioxide was raising earlier and our expert Dick figured out the issue for us. When the compressor was dumping the collector, the pressure on the filters was dropping, which was "breaking free" the carbon dioxide when the pressure came back up. We installed a one-way valve between the filters and the compressor and this solved the problem.
Filters need to be changed frequently to ensure good air quality. And the system needs to be drained everyday. We actually have a start up checklist for the compressor. Whenever I go diving, I always take a good look at the compressor and fill area. I have a new respect for clean, efficient and well maintained air systems.
If you ever want a tour of the air system, let me know. Greg
1 comment:
Who KNEW it was so complicated! You guys are brilliant!!!
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