How to Refill a SCUBA Tank
How to Refill a SCUBA Tank
You finally bought your own SCUBA tanks, now what? How do you refill a SCUBA tank? Let’s discuss some important steps to ensure a safe fill of air for your next dive.
The first thing to do before refilling a tank is to make sure it is within inspection dates. Tank inspections are for the safety of the filler and you as the diver. A visual inspection sticker is on every tank and lists the date the test was performed. Every year SCUBA tanks require a visual inspection. A certified inspector will release all of the air from your tank, unscrew the tank valve, and have a look inside for any cracks, rust, or corrosion.
If your tank passes this inspection, it will have a sticker attached to the tank with the date of the inspection. At this point, your tank will be refilled as part of the process. If your tank fails the inspection, it will be decommissioned and no longer able to be used.
Another test that a refill station will look for on your tank is a hydrostat test date. This is usually done every 5 years. A tank is drained of air and filled with water to test for expansion and leaks. Again, this is a pass or fail test. If it passes, the dates are stamped into the tank. If the tank fails this test, it is decommissioned.
The most obvious place to refill a SCUBA tank is a reputable SCUBA dive shop. These shops have the expensive air compressors that are under high regulation to ensure proper working conditions. Here you will receive air that is pure, clean, and dry. SCUBA shops are fun to visit as well. Check out some other gear while you are there, such as a new SCUBA diving wetsuit!
Some people want to know how to fill a SCUBA tank at home. This would mostly be due to convenience, but they also might be thinking cost. Air compressors can be bought for home use, but these usually only have a working pressures of 200 PSI. Your SCUBA tank requires a pressure of 3000 PSI to be refilled.
An air compressor capable of producing this kind of pressure is costly, not to mention the upkeep and inspections to ensure proper working order. Any contaminant, such as carbon monoxide, that gets into your tank will only be amplified under pressure and can be very dangerous. It is not advised to do at-home refills of your SCUBA tank.
Types of Fills
You may wonder why sometimes it takes a very long time to refill your SCUBA tank while other times it can be done quickly. We call these “hot fills” and “cold fills”. Refills of SCUBA tanks are done straight off of an air compressor. This type of fill produces heat. What this means is that a SCUBA tank filled to 3000 PSI as a hot fill will lose pressure as it cools off and typically drop to about 2700 PSI.
After it cools off, the tank can be topped off to get back up to 3000 PSI. Some SCUBA shops will fill a 3000 PSI tank to 3300 PSI during a hot fill. Technically this is beyond what the fill is supposed to be, but it is still well below the pressure needed to cause the burst disk to go off. When this tank cools, it will be near 3000 PSI.
Other methods of keeping the tank cool while filling could also be employed. One method is to immerse the tank in a cooling bath while it is being filled. This helps reduce the increase in heat inside to be able to fill to the working pressure of the tank. The tank could also be very slowly filled which also reduces the heat inside and allows the tank to reach working pressure.
Costs to Refill a SCUBA Tank
The actual cost to refill a SCUBA tank is low. Most SCUBA shops will charge on average $7, but this price could vary greatly from shop to shop. This is the best way to refill your SCUBA tank because a SCUBA shop will have highly regulated air compressors in good working condition. Of course, there are always those few untrustworthy shops so please do your own research on a SCUBA shop before visiting for a refill.
There you have it. How to refill a SCUBA tank is pretty easy if you think about it, especially if someone else does all the work! Just remember to be safe and have good working equipment to ensure a safe and happy dive!