SCUBA Tanks
Recently we had a customer at our Dive Center that wanted us to fill his SCUBA tank. When I looked at the tank the visual inspection was almost three years over due and the hydro test had expired the previous month. When I explained to him that I could not fill his tank without current hydro stamp and VIP (visual inspection program) sticker his response was "Thats ok, I know they are good."
I tried to explain that the requirement for testing is not something we made up but that it is a requirement of the Department of Transportation.
He then became quite agitated and loud accusing us of over charging for as he put it "dropping a light into a tank." He then became abusive and began attacking all our pricing and told us he could by equipment for half our prices on the internet or at a local sporting goods store.
I asked him to leave.
He parting shot was "An informed customer is your worst enemy." In fact, a misinformed customer is our worst enemy.
This article is our attempt ad helping our customer be informed. We will review testing and tank maintenance.
For a list of all our sites with tips on Dive Gear CLICK HERE
I tried to explain that the requirement for testing is not something we made up but that it is a requirement of the Department of Transportation.
He then became quite agitated and loud accusing us of over charging for as he put it "dropping a light into a tank." He then became abusive and began attacking all our pricing and told us he could by equipment for half our prices on the internet or at a local sporting goods store.
I asked him to leave.
He parting shot was "An informed customer is your worst enemy." In fact, a misinformed customer is our worst enemy.
This article is our attempt ad helping our customer be informed. We will review testing and tank maintenance.
For a list of all our sites with tips on Dive Gear CLICK HERE
New Table of Contents
Hydrostatic Testing
SCUBA tanks must be hydro tested every five years. In this test the tank is filled with water and then lowered into a water filled chamber. The tank is then pressurized to 5/3 of its operating pressure. The test is done with water instead of air because should there be a failure the water does not hold potential energy and the failure would be less explosive.Once pressurized the tank is measured for expansion. If the expansion is not within tolerances the tank fails the test and must be discarded.
The test is the same for aluminum and steel tanks.
Sea Lions Dive Center outsources this testing to a local testing service.
VIP - Visual Inspection Program
A visual inspection must be performed annually. For this inspection the tank is emptied and the valve removed. The tank boot and any clamps or other attachments must also be removed. The exterior of the tank is inspected for dents or other chips or damage that would make filling dangerous. There are standards for the number and depth of imperfections.If the tank passes this inspection a VIP sticker such as the one pictured is attached to the tank. The month and year of the inspection is punched on the sticker.
A light is then dropped into the tank and the interior is inspected by a certified technician for corrosion or contaminants. If the there corrosion or contaminants are present the tank must be tumbled and cleaned.
Tank Tumbler
If there is corrosion or contaminants in a SCUBA tank it can often be cleaned by tumbling. Nitrox tanks will also be tumbled annually.To tumble a tank the tank is filled about half full with a cleaning solution and with a tumbling media. The media is different for aluminum and steel tanks and is small rough particles that scourer the interior surface removing corrosion and contaminants.
The tank is then rinsed and dried prior to reinstalling the valve.
Sea Lions Logo Gear
The Manufacture of a SCUBA Tank
Eddy Current Test
Aluminum tanks manufactured before 1990 and made of 6351-T6 alloy have been found to be subject to neck cracks. These tanks need to have an eddy current test which involves screwing a threaded prob into the neck of the tank to test for cracks that may be too small to be seen by the naked eye. Tank Valves
Tank valves will occasionally leak. Rebuilding them is not difficult but the work is best done by experienced technician.If you have a rattle in your tank the shpyon tube show in the picture at the tank side of the valve may have loose. This tube is there to keep contaminates out of the valve
Other Sea Lions Sites
- Sea Lions Dive Center
- The official site of Sea Lions Dive Center
- Dive Gear
- Information on dive gear and purchasing dive gear on the internet
- Sea Lions Newsletter
- This is the blog of Sea Lions Dive Center with information on Sea Lions and information of interest to the diving community.
Tell us what you think and how we can make this page better
Lensmaster
Matthew Evans wrote
I'm in the process of learning how to visually inspect
tanks.
Your site is very informative & helpful to those of us in the industry who understand the complexities of handling & filling cylinders with 3000 pounds of explosive force!
Having better informed clients makes the job so much easier, & serves to protect them from the dangers of misuse & poor maintenance of equipment.
Thank You
Matthew Evans
Posted November 01, 2009
Lensmaster
Vinnie wrote
Very informative to the new diver or diver that likes to be informed .... very good, five stars
Posted July 09, 2009
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