Scuba Cylinders: Myths and some Facts

scuba cylindersScuba Cylinders, the not so sexy, sort of heavy thing that holds our breathing gas and allows us to spend some time in the underwater world. What do most of us know about them? Other than we may recall that during our open water class we heard about some test that are required. And there are different sizes. But the scuba cylinders are somewhat of a mystery outside of that.

The making of scuba cylinders is an interesting process. From how they are formed from a solid piece of aluminum or steel to the final product that you find on your dive boat. They are the heart and soul of any dive adventure, since without them we wouldn’t be underwater very long. And with proper care, they will last a very long time.

Did you know that the amount of air inside an 80 cubic foot tank contains the amount of air that was found in a traditional phone booth? Do you remember phone booths? And that amount of air has approximately 1.3 million-foot pounds of energy. Scuba cylinders a like a bomb on our backs. Ok, maybe more like two hand grenades. And we are taking them into the ocean and they are getting banged around on the boat and at the dock and yes, even when they are getting filled. Amazing that scuba cylinders are so stable and safe.

This is the reason that we have those tests. And every 5 years we have them hydro statically tested. Basically, we try and blow them up. Then they are visually inspected. And every year all the scuba cylinders and visually inspect them. The biggest failure spot in scuba cylinders is in the threads. A small hair line crack that runs through 2 to 3 threads is a major weak spot. They are usually found with magnification or a light electrical current. Any weak spot with that much energy pushing against it, is dangerous. We also, look for pitting and other anomalies.

Can scuba cylinders explode if left in my trunk all day? Well, not really. Charles’ Law will tell us that as the gas warms inside the cylinder in your trunk, that gas will expand. Your cylinder has a burst disc in the valve. Most are rated for 3500 PSI. So, when the pressure of the expanding gas reaches 3500 PSI it will “pop” that safety disc and the air will bleed out. Yes, the noise will scare the senses out of you. But it is not going to go shooting off in your car and bouncing around.

Now for the big myth. I will leave you with the TV Show Myth Busters.