Alloy Dive Cylinder Myth

I have been doing some investigations regarding Aluminum Dive Cylinders.

I spoke to Work Cover NSW the author of the Safety Alert No 2217 (see attached).

Work Cover can not ban the testing or filling of of these cylinders, only make everyone aware of the problems that have arisen over the past 12 months

As you are aware all cylinders must be hydro tested every 12 months . If the cylinder passes hydro it is then up to the individual filling stations to decide whether they will fill the tank.

As long as the following control measure are met there should not be a problem with refilling the tanks (extract from safety alert)

The following control measures apply when filling cylinders, including aluminium SCUBA cylinders:

inspect a cylinder before filling it

do not fill, or use, a damaged cylinder – eg if there is evidence of surface gouging, cuts, dents or damaged fittings

do not fill a cylinder that is without a valid test date stamped on it – SCUBA cylinder tests are only valid for 12 months

do not fill a cylinder to a pressure that is greater than the working pressure stamped on it

fill a cylinder slowly to prevent an excessive rise in temperature, or if filling it faster, remove the excessive heat during filling, by refrigerating the gas or immersing the cylinder in cold water

do not tamper with the valve unit safety valve fitting or rupture disc

do not approach the cylinder if you detect a leak – don’t assume the leaking sound is due to a leaking connection of the filling apparatus. Evacuate the area and allow the cylinder to discharge, or discharge the cylinder once you consider it safe to do so. Only investigate the cause of the leak when the cylinder has discharged.

flexible connections (eg hoses) should be suitably restrained before filling, otherwise they may whip if the hose bursts or disconnect when pressurised.

I then contacted a licensed testing station on the South Coast of NSW for cylinders. He will hydro test all aluminum cylinders as per the required standards. In addition, for the pre 1993 cylinders he does an eddy test, which will pick up any cracks that are too small to be seen by the naked eye. An eddy test runs an electrical current through the tank. After that if the tank passes it will be stamped and issued with a certificate.

Now you may ask how much will this set us back for these tests. Testing station charges are as follows:

                        $25.00 for the standard Hydrostatic Test        this includes all alloy and steel tanks

                        $10.00 for the additional Eddy test for pre 1993 alloy tanks

These prices sure beat the fees quoted by other people.

Some filling stations especially around Sydney are adopting the attitude that pre 1993 cylinders will not be filled. So if you wish to retain your Alloys, check with the fillers to see if they will be filled.

There are no alerts or restrictions on steel cylinders. Only that they should not be emptied completely, as they will suck moisture back and be aware of rust. This can be avoided by leaving at least 50bar in the tank and cleaning gear after dives.

I hope this clears up some issues regarding the Alloy tanks. Hopefully I will publish the Testing Station contact details shortly.



Web Editor June 2010



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