runsongas
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The German and Japanese tanks are spun not pressed which is why they have those heavy bottoms
What's in a hydro?
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That by itself is a true statement, but a cylinder can be re-tested if there is any suspicion of an equipment failure (a leak in the neck connection or system, etc).
The way I see it, if a steel 72 (and many other steel cylinders, specially 3AA code cylinders) fails it is most likely an equipment failure. It is so unlikely that a non-corroded or a steel cylinder that has not been exposed to a fire, will fail, that I considered it enough of a proof that it is an equipment failure (a leak, etc). Therefore, I will advocate for it to be re-tested.
If it is re-tested using the proper re-test procedure (per the CFR) it is very likely going to pass (it always has in my observations). Basically proving my point that it was an equipment failure. But, in reality it is also very possible that they did not followed the proper pre-test procedure (for a galvanized cylinder).
In either case, by calling it an equipment failure you can technically redo the test per the Code of Federal Regulations (CFR). This is legitimate since the probability is relatively high, that it was indeed equipment failure, as compared to the very small number of cylinder failures.
Now, trying to find a hydro facility that will give a dam about your one galvanized cylinder when he has to do hundreds of painted fire extinguisher cylinders a week… good luck.
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@Luis H we are very lucky here in the Carolinas that we have Safe Air Systems who is VERY busy with oxygen bottles, fire extinguishers, SCBA bottles etc. but whenever they get SCUBA tanks in, any rigging that's on there goes back where it was, tank valves are always put back on the right cylinder, and regardless of whether or not they are galvanized or not, they perform a round out procedure because they say that even the painted on zinc of the Faber bottles has caused some issues in the past. Nothing says they can't perform a round out on every bottle, so they just do it on every round of scuba tanks
The first hydro machine I worked on was at Divers Service Center in Puerto Rico. I actually helped install the hydro machine. I think we installed it in 1972. What I mean by help installed, included that I helped dig the hole in the ground to put the tall container/ jacked tank for testing the large cascade type of cylinders.
Back then we did not use the quick disconnect adapter fittings. All the threaded adapters had to be screwed to the 1/2” NPT on the lid of the test chamber/ jacket. We used pipe dope not Teflon tape for this fitting since it had to be disconnected on a regular basis.
Having leaks was not uncommon and it only takes a miniscule leak to throw off the test results. Keep in mind that we are trying to measure cubic centimeters (CC) and decimals of CC’s.
Therefore, it was customary that we always perform a leak test before we actually took data for the actual hydro test. According to the codes that (as far as I can remember) it was allowed to do a leak test at 90% of the test pressure and we always did.
We were not aware that we were also doing the pre-test that the manufacturers would require decades later. But we mostly tested steel 72 and they never failed. And it wasn’t because of their age, because steel doesn’t age with time.
The only thing that time (age) does to steel is that it provides more opportunities for rust to form. But the steel itself is not affected by time. So, when I hear somebody saying that the tank fail because it is too old, it just shows pure ignorance.
When visiting PR in 2007 I saw the old hydro machine. It looks awful, but I hear that it is still operating. It was semi-outdoors so we only used it on sunny days, but it was sheltered from direct rain. I will try to post pictures later.
Back then we did not use the quick disconnect adapter fittings. All the threaded adapters had to be screwed to the 1/2” NPT on the lid of the test chamber/ jacket. We used pipe dope not Teflon tape for this fitting since it had to be disconnected on a regular basis.
Having leaks was not uncommon and it only takes a miniscule leak to throw off the test results. Keep in mind that we are trying to measure cubic centimeters (CC) and decimals of CC’s.
Therefore, it was customary that we always perform a leak test before we actually took data for the actual hydro test. According to the codes that (as far as I can remember) it was allowed to do a leak test at 90% of the test pressure and we always did.
We were not aware that we were also doing the pre-test that the manufacturers would require decades later. But we mostly tested steel 72 and they never failed. And it wasn’t because of their age, because steel doesn’t age with time.
The only thing that time (age) does to steel is that it provides more opportunities for rust to form. But the steel itself is not affected by time. So, when I hear somebody saying that the tank fail because it is too old, it just shows pure ignorance.
When visiting PR in 2007 I saw the old hydro machine. It looks awful, but I hear that it is still operating. It was semi-outdoors so we only used it on sunny days, but it was sheltered from direct rain. I will try to post pictures later.
Here are some pictures of Divers Service Center in 2007. It has changed a bit since I worked there in the 1970's. But the owner Alberto is still the same.
I should add that the pictures of the hydro machine shown below are not what you normally see in most facilities in the continental US. First they are normally blue (not white) because most of them come from the same manufacturer. This one was also blue when we first installed it. They are also much cleaner and they are normally on an indoor facility. In PR they are not concerned about water freezing.
On the flip side, these guys probably do as good a hydro testing as anyone else. But the facility does look bad...
The hydro machine console is on the right . You can see the control valves on the top surface. They painted it, but the labels are missing.
The two white cylinders on the left are the test chambers or water jackets. The one on the far left was added later. I never saw it before. The one on the center of the picture is the one that goes several feet into the ground. The oxygen cylinders on the right will fit in that chamber.
Here is a closer look of the two chamber (water jackets). The blue cylinder on the right is the calibration test cylinder. That cylinder is designed to always returned to zero after pressurized to the maximum test pressure of that day. It is a very thick wall cylinder and for all the test pressures in this facility it will only expand within its elastic range. It is supposed to use for calibration every day a hydro is performed.
To the left of the console you can see the burettes and the calibrated pressure gauge.
While I am showing picture, here is a picture of the tumbling machine that can handle the large cascade bottles. Yes, the place is a mess. This is all on back side of the dive shop.
This is on the side hallway where we used to keep the operating compressors. The big blue box is a compressor, but I don't know if it is connected.
I don't remember ever seen so much mildew.
This the actual dive shop on the inside. It doesn't look to bad for a dive shop that has been around close to 50 years. It has changed a bit since I worked here.
The glass window is the front of the store.
I should also add, that I don't know how it looks like now, after the hurricanes. I have not been in touch with Alberto for several years. I should probably give him a call...
I should add that the pictures of the hydro machine shown below are not what you normally see in most facilities in the continental US. First they are normally blue (not white) because most of them come from the same manufacturer. This one was also blue when we first installed it. They are also much cleaner and they are normally on an indoor facility. In PR they are not concerned about water freezing.
On the flip side, these guys probably do as good a hydro testing as anyone else. But the facility does look bad...
The hydro machine console is on the right . You can see the control valves on the top surface. They painted it, but the labels are missing.
The two white cylinders on the left are the test chambers or water jackets. The one on the far left was added later. I never saw it before. The one on the center of the picture is the one that goes several feet into the ground. The oxygen cylinders on the right will fit in that chamber.
Here is a closer look of the two chamber (water jackets). The blue cylinder on the right is the calibration test cylinder. That cylinder is designed to always returned to zero after pressurized to the maximum test pressure of that day. It is a very thick wall cylinder and for all the test pressures in this facility it will only expand within its elastic range. It is supposed to use for calibration every day a hydro is performed.
To the left of the console you can see the burettes and the calibrated pressure gauge.
While I am showing picture, here is a picture of the tumbling machine that can handle the large cascade bottles. Yes, the place is a mess. This is all on back side of the dive shop.
This is on the side hallway where we used to keep the operating compressors. The big blue box is a compressor, but I don't know if it is connected.
I don't remember ever seen so much mildew.
This the actual dive shop on the inside. It doesn't look to bad for a dive shop that has been around close to 50 years. It has changed a bit since I worked here.
The glass window is the front of the store.
I should also add, that I don't know how it looks like now, after the hurricanes. I have not been in touch with Alberto for several years. I should probably give him a call...
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OP
Very cool pictures and story.
Curious if testers are required to keep records of any 90% leak checks performed.
Curious if testers are required to keep records of any 90% leak checks performed.
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As @tbone1004 mentioned, they are not required to keep records of the leak check (pre-test) and if you actually have to chase and fix a leak you may end up doing it more than once. I have had to repeat the leak check a few times, but normally got it on the second try.
If a leak was bad we could tell long before we got to 90% pressure, but not with a small leak.
Leaks are not as common with the newer set-ups. For the last few years I had an LDS with a hydro machine and I often helped them do hydros (I always did my own). Leaks were very, very rare.
If a leak was bad we could tell long before we got to 90% pressure, but not with a small leak.
Leaks are not as common with the newer set-ups. For the last few years I had an LDS with a hydro machine and I often helped them do hydros (I always did my own). Leaks were very, very rare.
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