inspect your own tanks

[fppf]

Dallas at Discover Diving will teach it in Buffalo NY
You need to call him and ask about it, not something they advertise often. You can also go to PSI's web site and they have a list of classes offered.

 

[Doc Harry]

How much would the eddy current testing equipment cost? I've had tanks pass the hydro, the vis and then fail the eddy.

It would be significantly cheaper the turn those cylinders into flower pots and buy new tanks that don't need eddy current testing, than to buy eddy current testing equipment.

PSI has a great cylinder inspector course, likely the best course around.

 

[Rhone Man]

The visual inspection is there for your safety and the safety of the people that fill your cylinders. If you do this and someone gets hurt its your neck. Any cylinder that is used in the water has the remote chance of getting water in it. You also breath from that cylinder, its a really good idea to know what is in it. You would not believe the crap that can get into cylinders. It only takes once to have a really bad day. This is not a money grab like some think. I will admit though some shops charge a really high fee for this service.

That is a common view in North America, but having worked as a VIP inspector in a dive shop for a year, I am extremely reserved about the benefits of annual VIPs. I also note that in the UK, where VIPs are only done every 2.5 years, divers do not seem to be dying like flies and tanks do not seem to be exploding left and right. It is also worth noting that other forms of cylinders containing breathable gas (I am thinking of medical oxygen here) do not require annual VIPs.

I remember when I was doing my gas blending course, my instructor was telling me a story about when he was at his gas suppliers, and they cracked open a cylinder which was to be filled with medical oxygen to show him - it had about 6 inches depth of rust flakes at the bottom. Then they put the valve back on, filled it, and sent it to the hospital for the cancer patients to breathe.

 

[Doc Harry]

That is a common view in North America, but having worked as a VIP inspector in a dive shop for a year, I am extremely reserved about the benefits of annual VIPs...

History is doomed to be repeated because the past is forgotten....

Actually, if you review the history of the scuba cylinder, annual inspections are the result of many problems that surfaced (no pun intended) during the early days of scuba diving. In the the 1970s the US Navy hired private consultants to look at the problems that the US Navy was having with cylinders. Universities also conducted their own investigations and experiments with scuba cylinders.

If you want to look at some of the original research, you can buy one particularly interesting study here: INVESTIGATION OF SCUBA CYLINDER CORROSION, Phase 1 (1970)

From the abstract: "...Recommendations were formulated concerning changes in manufacturing specifications, cleaning procedures, and inspection procedures to provide increased assurance that corrosion will not progress to the point of significantly degrading the rupture strength of aluminum scuba cylinders."

All of current cylinder inspection and handling procedures (such as annual VIPs) are based on all of the problems and studies from 30-40 years ago when cylinders were not really regulated. One of the reasons that people today are skeptical of utility of these inspection procedures is that there are so few cylinder problems nowadays, and this is a direct result of annual VIPs.

 

[fppf]

Well said Harry.
Rhone
Your trying to compare apples and oranges here. Our cylinders are used in a wet environment, they get submerged to depths, they sit on boats, splashed all the time. Dive cylinders just don't sit on the floor, they are turned up side down, shaken, stirred, rolled, and any other position you can think of. This is a far harsher environment then a medical or industrial cylinder will ever see.

I don't know what sample of cylinders you have seen in just a year. But our shops still see bad cylinders come through the doors. Line corrosion around cylinder boots, enough aluminum oxide to powder your face with, chunks of rust falling out, ounces of water in the bottoms.

 

[Scared Silly]

Your trying to compare apples and oranges here. Our cylinders are used in a wet environment, they get submerged to depths, they sit on boats, splashed all the time. Dive cylinders just don't sit on the floor, they are turned up side down, shaken, stirred, rolled, and any other position you can think of. This is a far harsher environment then a medical or industrial cylinder will ever see.

I disagree slightly, the only difference between a scuba cylinder and another other cylinder is that it is used underwater. Many divers take really good care of their cylinders others could give a hoot. Not much different than those cylinders clanking around in the back of a welder's truck in the rain and snow. However, the fact that they are used underwater and in salt water is reason enough for them to be checked at regular intervals.

The real problem is the way the scuba industry has dealt with the inspection program. Just look at all the variance in shop rules and just who does the inspections.

 

[fppf]

I disagree, the only difference between a scuba cylinder and another other cylinder is that it is used underwater. Many divers take really good care of their cylinders others could give a hoot. Not much different than those cylinders clanking around in the back of a welder's truck. However, the fact that they are used underwater and in salt water is reason enough for them to be check at regular intervals.

The real problem is the way the scuba industry has dealt with the inspection program. Just look at all the variance in shop rules and just who does the inspections.

For the first part, I don't think many divers know about high pressure cylinders. In addition, I don't know many industrial or medical cylinders that are flipped upside down while in use. Most just sit on the floor.

Second part, I agree. The whole industry tries to drape a black vale around all this stuff. Its like there the only industry that deals with high pressure cylinders and regulators. This only adds to the skepticism of the consumer. Now granted, not many sports deal with large volume high pressure cylinder and regulators. I feel the best policy is honesty and education. Which from what I have found most shops do now. One of our local shops goes through a whole evening of talking about cylinders and regulators in depth during there master diver course. They show cut away sections of cylinders and regulators as well. This really gives people a good feel for why they are spending there money getting gear serviced and cylinders inspected.

I think you will also find the major majority of shops are within a close price range for these common services. And if you have ever personally done any of these services you will also know there not raking in the doe hand over fist by any means.

 

[Slamfire]

It would be significantly cheaper the turn those cylinders into flower pots and buy new tanks that don't need eddy current testing, than to buy eddy current testing equipment.

I had no idea eddy equipment was so expensive. I think the oldest tank that I now have had it's first hydro in 1986. I'm attaching a pdf report of the two latest inspections I've had. These are Luxfers from 1993 and 1995. The eddy test was done on both. I don't mind it being done. I still pay only slightly higher prices than a tank fill and the vis includes a fill.

 

[duckbill]

Actually, if you review the history of the scuba cylinder, annual inspections are the result of many problems that surfaced (no pun intended) during the early days of scuba diving. In the the 1970s the US Navy hired private consultants to look at the problems that the US Navy was having with cylinders.

Exactly. And those were the days before SPGs when tanks were routinely sucked down to empty or near empty. Today with SPGs, if the diver does his part and does not empty his tank, then any water in the cylinder is likely the fault of the compressor operator, which is usually a dive shop.

There is no way water will get into a cylinder while diving that has a little more pressure in it than ambient pressure. That would be about 60 psi at 100 feet. Unless a diver gets his tank pressure well below reserve pressure, it is unlikely he would be responsible for getting water in this tank unless his valve is wet when installing the regulator.

Water at the fill connection, or improperly maintained compressor filters are much more likely to be the cause of significant internal corrosion. If dive shops worry about cylinders that aren't checked every year, it is probably their own fault (in a collective sense).

That said, I mostly fill my own tanks and check them every year. Even though I know the history of my tanks and compressor, it doesn't hurt to check. So far, so good.

JMO

 

[Gilldiver]

There is no way water will get into a cylinder while diving that has a little more pressure in it than ambient pressure. That would be about 60 psi at 100 feet. Unless a diver gets his tank pressure well below reserve pressure, it is unlikely he would be responsible for getting water in this tank unless his valve is wet when installing the regulator.

Water at the fill connection, or improperly maintained compressor filters are much more likely to be the cause of significant internal corrosion. If dive shops worry about cylinders that aren't checked every year, it is probably their own fault (in a collective sense)

Depending on your regulator, you may not be able to get much, if at all, below the IP pressure of somewhere between 120-145.

The Rhode Island study is more then a bit bogus as it put 500 ml of water into a cylinder. That is the equivalent of a Kinger of Bud, not likely to occur. It also showed that fresh water was not all that bad, but salt was the killer to tanks. The major sources of water entrainment is wet valve connections at the time of filling and poorly maintained compressors. Compressors on boats being some of the worst with a lot of posts on very poor reports on compressors on Southern Cal boats. I do remember a tank I borrowed from a dive who crewed on one of the NY/NJ boats in the late 80's, I had this tank in Lake George and was getting a very strong salt taste, that tank got blown down and rinsed out.

The bottles that I see being the worse treated are small ones used for dry suit fill. I have seen more then a few of these bottles trashed in less then a few years. Divers just don't care if there is no gas left in them, they just keep hitting the suit fill button and then never spin the valve off and take a look inside.