Hydro

[LBHeyman]

Does anyone know if it is necessary to take your tanks to your LDS, or can you just take them straight to the hydro place? Cut out the middle man. If you can, where would you start to find one?

 

[Scared Silly]

No need to take them to the dive shop for the hydro. To find out where call any place that provides high pressure gas - welding supply, medical supply, soda company, etc. and asl them where they take their cylinders.

That said a hydro is a DOT requirement. Your dive shop may still want to do a full "scuba" vis and put a sticker on it. However, understand that at the time of hydro a vis is done as part of the process. So technically the hydro is proof of a vis. That said a hydro facility will rarely pressurize your cylinder afterwards so you have an empty cylinder. Which is reason enough for a shop to want to do a vis.

 

[ArcticDiver]

If one is available take the cylinder directly to the hydro facility.

Some dive shops will not only want to do a Vis after the hydro they may want to tumble the cylinder to remove corrosion. I don't know how common that is but one of the shops I do business with insisted on both a vis and an anti-corrosion tumble before they will fill a cylinder if a hydro was not done through them.

 

[bigken462]

We have a place here that does those too, and while I can't suggest either way if they will or not, I thought I would mention as a reminder to be sure and tell the shop if you have any of the LP cylinders that needs the + rating to be sure to mention that to them otherwise, you will not be able to overfill as you normally do.

Kenny

 

[eandiver]

For you I would suggest you try here. FloridaScubaRepairs index

 

[captain]

List of hydro testers.

Authorized Hydrostatic Retesters

 

[Regtekdiver]

You could take your cylinders to any local industrial hydro facility. However, a hydro stamp does NOT imply a visual inspection. Your cylinder will still need a visual inspection every year. Anyone filling a SCUBA cylinder at a dive shop is looking for a hydro stamp AND a visual inspection sticker. Your "LDS" will only suggest a tumble to remove corrosion if it is a steel cylinder that developed corrosion after the hydro (this is not an issue with aluminum cylinders). Most dive shops who do business with a hydro facility require them to rinse the cylinder with very hot water after the test to quickly dry the cylinder so no corrosion develops. If this is done you will most likely have no problems. If you take your cylinder to a hydro facility as a private party you most likely will not recieve the same hot water rinse and are only asking for trouble. This is life support people... let the dive shop handle it.

 

[DA Aquamaster]

You could take your cylinders to any local industrial hydro facility. However, a hydro stamp does NOT imply a visual inspection. Your cylinder will still need a visual inspection every year.

Sorry...DOT requalification of a scuba tank requires both the hydrotest and a visual inspection - and for AL tanks an eddy current inspection is also required.

So a hydro test stamp does in fact mean the tank also passed a visual inspection.

It does not however satisfy many shops who want to also do their own VIP. Looking in the tank when it comes back from hydro testing is a good idea, especially if the valve is off and it is easy and quick to do as the tank is already empty - but the tank has indeed already had a visual inspection or it would not have been requalified and saying it "requires" another one at that time is redundant.

The annual VIP requirement is a dive industry standard and I agree 12 months after hydro, another VIP would be needed to meet that non legally required standard.

Most dive shops who do business with a hydro facility require them to rinse the cylinder with very hot water after the test to quickly dry the cylinder so no corrosion develops. If this is done you will most likely have no problems. If you take your cylinder to a hydro facility as a private party you most likely will not recieve the same hot water rinse and are only asking for trouble. This is life support people... let the dive shop handle it.

That is just plain innacurate. I have yet to see the tank test facility that did not take pains to properly dry steel tanks regardless of whether they do scuba tanks, SCBA tanks, CO2 tanks, welding tanks or medical or aviator O2 tanks. Some flash rusting is normal even with a hot water rinse and a hot air dry.

To avoid any flash rust in a steel tank you either have to use a phosphating process or you have to dry the tank with nitrogen or another gas containing no O2 to ensure oxidation does not occur - and hydro test facilities do not do either process even with steel medical or aviator O2 tanks.

For AL tanks it is entirely a non issue as long as the tank is ultimately dry before it is revalved.

And while it is life support, it is not rocket science.

 

[oxyhacker]

Many VIP stickers and manuals actually reference CGA C-6 and 6.1, which are the CGA pamphlets that set the standards for visually inspectiong tanks at hydro time. So there is not as much difference between an annual visual and the one done at hydro, as many would have us believe. Though eddy current is only required for 6351 "bad alloy" tanks.

Sorry...DOT requalification of a scuba tank requires both the hydrotest and a visual inspection - and for AL tanks an eddy current inspection is also required.

So a hydro test stamp does in fact mean the tank also passed a visual inspection.

I haven't ever seen a hydro shop that uses hot water either. The good ones throw the tank immediately upon draining onto a draining/drying rack, and blow some hot air through them. The bad ones usually will invert them, at least, so they can drain. Phosphating isn't really used at the hydro shop level - it's done to new tanks mostly as a byproduct of the cleaning process, and doesn't give long term protection. The stuff (some) hydro shops use to keep the tanks from rusting before they can dry is DEA.

Personally, I'd rather put up with some light surface rust than more chemicals in my air. Rust is not as big as a concern as tumbler-happy diveshops would have us think. CGA C-6, which is as close as there is to an official visual inspection protocol, while going into great length about evaluating pit, crevice, line and general corrosion, and how much loss of wall thickness can be tolerated before a cylinder fails, nowhere states that just the presence of rust alone is grounds for rejection. RR-C-901D, which sets the official standards for tank cleaning, says "Rust bloom generated subsequent to inspection as a result of handling is acceptable". And the old Pressed Steel company said "With use, the cylinder interior may take on a reddish cast due to the development of a light rust bloom. This should not be considered harmful and need not be removed, unless in the opinion of a qualified technition the corrosion is heavy enough to hide possible pits or harmful gouges."

That is just plain innacurate. I have yet to see the tank test facility that did not take pains to properly dry steel tanks regardless of whether they do scuba tanks, SCBA tanks, CO2 tanks, welding tanks or medical or aviator O2 tanks. Some flash rusting is normal even with a hot water rinse and a hot air dry.

To avoid any flash rust in a steel tank you either have to use a phosphating process or you have to dry the tank with nitrogen or another gas containing no O2 to ensure oxidation does not occur - and hydro test facilities do not do either process even with steel medical or aviator O2 tanks.

 

[ArcticDiver]

You could take your cylinders to any local industrial hydro facility. However, a hydro stamp does NOT imply a visual inspection. Your cylinder will still need a visual inspection every year. Anyone filling a SCUBA cylinder at a dive shop is looking for a hydro stamp AND a visual inspection sticker. Your "LDS" will only suggest a tumble to remove corrosion if it is a steel cylinder that developed corrosion after the hydro (this is not an issue with aluminum cylinders). Most dive shops who do business with a hydro facility require them to rinse the cylinder with very hot water after the test to quickly dry the cylinder so no corrosion develops. If this is done you will most likely have no problems. If you take your cylinder to a hydro facility as a private party you most likely will not recieve the same hot water rinse and are only asking for trouble. This is life support people... let the dive shop handle it.

Inaccurate on a couple points:
First: The tumble and visual was required regardless of cylinder material. In that shop's view corrosion is corrosion whether aluminium or steel. In fact both steel and aluminium tanks corrode and can and do have visible corrosion.

Second: It isn't the dive shop that sets the standards; it is the Government rules.

Third: With the shape of most high pressure cylinders drying by just waiting for natural evaporation will not vary much within a wide range of water temperatures. If you want the cylinder dry better, aid evaporation somehow.

Fourth: Given the relative level of regulatory control I'd say the hydro facility is more likely to have sufficient respect for the life safey aspects of hydro. They hydro lots of cylinders for lots of knowledgable customers. You can bet they aren't going to endanger that business by not following the rules or by not having untrained people do the work. I can't say the same for some dive shops.