Plus ratings and hydros'

[Tamas]

NO, No, no!!! That's not correct.

For the DOT / CTC cylinders (only allowed in Canada if mfg before 1993), the TC plus requirements are basically the same as in the US - you can only plus if don't exceed the REE. See B339 24.6.3.3.

The difference is in the new TC metric cylinders which have the 110% fill pressure built in to the marked service pressure. But, even on these, if you exceed the REE, you must DOWNGRADE the cylinder by stamping a "K" following the service pressure, and then the fill pressure is REDUCED by 10%.

Not as simple as you thought, eh?

Cheers,

DG

Crap

 

[phillybob]

EIGHT PAGES !! ?? GEEZ !! I started a real poop storm !!

 

[douglasville diver]

thank you all

 

[captain]

Thanks much for the PST REE. Would it also be relatively close to what would be expected for the equivalent 72 produced by Norris. I emailed Norris some time back with a request for it and they replied that they no longer had that information. Possible they did not want to release it to an unknown person.


Maybe you have some insight to this issue. I sent a group of 4 galvanized 72's a mix of both PST and Norris in for hydro. The highest total expansion of the 4 was 58.3, the highest elastic was the same tank at 56.7 and permanent was 1.6, all passed with a high of 3.7% and a low of 1.8%, test pressure was recorded as 3700 psi.

Several months later I brought another 4 tanks, again a mix of PST and Norris to the same facility. In both instances I gave them a copy and made them aware of PST round out procedure and to my knowledge both groups were tested by the same individual.

In the second group the highest total expansion was 61.3 the lowest 60.5, the highest elastic was 60.2 but it was from a tank with a total of 60.8, this tank also had the lowest permanent at .6, the lowest total of the group was 60.5 and the lowest elastic was 58.6 they all passed with a high of 3.1% and a low of 1.0%, test pressure was recorded at 3800 psi.

Although all in both groups passed in the same range of percentages what can explain the higher overall expansions in the second group compared to the first group. Would the 50 psi higher test pressure be a factor.

 

[ctcdg]

Thanks much for the PST REE. Would it also be relatively close to what would be expected for the equivalent 72 produced by Norris. I emailed Norris some time back with a request for it and they replied that they no longer had that information. Possible they did not want to release it to an unknown person.


Maybe you have some insight to this issue. I sent a group of 4 galvanized 72's a mix of both PST and Norris in for hydro. The highest total expansion of the 4 was 58.3, the highest elastic was the same tank at 56.7 and permanent was 1.6, all passed with a high of 3.7% and a low of 1.8%, test pressure was recorded as 3700 psi.

Several months later I brought another 4 tanks, again a mix of PST and Norris to the same facility. In both instances I gave them a copy and made them aware of PST round out procedure and to my knowledge both groups were tested by the same individual.

In the second group the highest total expansion was 61.3 the lowest 60.5, the highest elastic was 60.2 but it was from a tank with a total of 60.8, this tank also had the lowest permanent at .6, the lowest total of the group was 60.5 and the lowest elastic was 58.6 they all passed with a high of 3.1% and a low of 1.0%, test pressure was recorded at 3800 psi.

Although all in both groups passed in the same range of percentages what can explain the higher overall expansions in the second group compared to the first group. Would the 50 psi higher test pressure be a factor.

Find a new retester.

(Ha! With my luck, it's probably someone I trained!!)

Those first tests are INVALID. For a 3AA2250 the test pressure is 3750psi. That is a minimum test pressure. Anything under that isn't a test! The next tests at 3800 are well over the 1% accuracy requirement called for by the DOT, so it sounds to me like the test operator either doesn't know what he's doing, or he has the wrong gauge (if he can only read 50 or 100 psi increments, that gauge doesn't qualify for testing at these pressures).

If the Norris cylinders are 3AA2250's with basically the same nominal dimensions, then the REE numbers should be close. I also have contacts at Norris. I can see if I can get their REE's. If so, I'll post those as well.

Next, would that difference in test pressures cause the difference in expansion? You bet! In my post to Scared Silly, I said that cylinders expand in a linear fashion. If you take the ratio of 58.3cc at 3700psi, at the CORRECT test pressure of 3750, that cylinder would have had about 59.1cc, and at 3800 it would have had about 59.9cc (pretty close to the 60.5 to 61.3 recorded). Also, with all the test pressures listed at 3700 and 3800, as I said before, the guy probably can't see less than 50 or 100 psi increments, so those actually could have been 3675 and 3825 and the guy never would have seen it. Using those numbers I get 60.7cc at 3825. Gee, funny how that works, huh?!!

For testing at 3750, the retester must have a gauge that is readable and accurate to within 1% of the test pressure (37psi). If DOT saw that test report with a 3700psi test pressure recorded for a 3AA2250, the retester would be looking at a violation in the neighborhood of $3,000 (they can fine up to $50,000 PER INFRACTION!!!).

By the way guys, the penalty for improperly "+" marking a cylinder is $2,000 to $4,000!! Don't be surprised when your retester is a little hesitant to do this if he isn't sure about the numbers.

Bottom line: Would you dive with an uncertified schmuck who bought some tanks at a garage sale? If you don't see a CTC Seminars Training Certificate hanging on the wall at the retest facility, turn around and walk out the door. I would be happy to provide a list of retesters in your area who has had proper training. I've trained over 4,000 people - I'm sure there's someone in your area.


DG

 

[captain]

Find a new retester.

(Ha! With my luck, it's probably someone I trained!!)

Those first tests are INVALID. For a 3AA2250 the test pressure is 3750psi. That is a minimum test pressure. Anything under that isn't a test! The next tests at 3800 are well over the 1% accuracy requirement called for by the DOT, so it sounds to me like the test operator either doesn't know what he's doing, or he has the wrong gauge (if he can only read 50 or 100 psi increments, that gauge doesn't qualify for testing at these pressures).

If the Norris cylinders are 3AA2250's with basically the same nominal dimensions, then the REE numbers should be close. I also have contacts at Norris. I can see if I can get their REE's. If so, I'll post those as well.

Next, would that difference in test pressures cause the difference in expansion? You bet! In my post to Scared Silly, I said that cylinders expand in a linear fashion. If you take the ratio of 58.3cc at 3700psi, at the CORRECT test pressure of 3750, that cylinder would have had about 59.1cc, and at 3800 it would have had about 59.9cc (pretty close to the 60.5 to 61.3 recorded). Also, with all the test pressures listed at 3700 and 3800, as I said before, the guy probably can't see less than 50 or 100 psi increments, so those actually could have been 3675 and 3825 and the guy never would have seen it. Using those numbers I get 60.7cc at 3825. Gee, funny how that works, huh?!!

For testing at 3750, the retester must have a gauge that is readable and accurate to within 1% of the test pressure (37psi). If DOT saw that test report with a 3700psi test pressure recorded for a 3AA2250, the retester would be looking at a violation in the neighborhood of $3,000 (they can fine up to $50,000 PER INFRACTION!!!).

By the way guys, the penalty for improperly "+" marking a cylinder is $2,000 to $4,000!! Don't be surprised when your retester is a little hesitant to do this if he isn't sure about the numbers.

Bottom line: Would you dive with an uncertified schmuck who bought some tanks at a garage sale? If you don't see a CTC Seminars Training Certificate hanging on the wall at the retest facility, turn around and walk out the door. I would be happy to provide a list of retesters in your area who has had proper training. I've trained over 4,000 people - I'm sure there's someone in your area.


DG

The 3700 was a typo on my part test pressure was 3750 on the tester's record sheet.

 

[halocline]

I wouldn't mind knowing the CTC retesters in San Antonio.

 

[ctcdg]

These companies should all be able to do your cylinders. Don't worry that their name says "Fire", most of them are doing SCBA's for firemen and shouldn't have any problem with your SCUBA's.

M. Jacks Fire & Safety
538 Sandau Rd.
San Antonio TX 78216
210-344-2361

Cintas Fire Protection
3349 SE Loop 410
San Antonio TX 78222
210-680-8811

U.S. Fire & Safety Equip. Co.
PO Box 28484
San Antonio TX 78228
210-680-8811

Cintas Fire Protection
7860 Mainland Dr., #1
San Antonio TX 78250
210-680-8811

 

[SparticleBrane]

Test results from my PST LP80s:

Pre-test and actual hydro test.

Sorry for the bad photos. One of these days when I find those test results again, and find the power cord for my scanner, I'll scan them in for a better copy.


Thank you very much for the PST LP72 REE numbers. On the PDF you provided, it says that they are under DOT spec "3AA250" rather than "3AA2250" -- is this a typo, or am I missing something?

 

[ctcdg]

Yeh, I saw that, too. Just a typo.

Uh... was I supposed to answer something on the test reports? I looked back through your posts and didn't see a specific question on these.

They look good. In fact these show EXACTLY what WD8CDH was talking about in post #51 about "rounding out" the cylinder. Notice that your pre-test permanent expansions came in at 2.3cc and 1.1cc. Then, at actual test pressure, the perm was only 0.3cc and 0.5cc, respectively. Had those first pre-tests actually experienced permanent expansion due to yield, when you went up to the higher test pressure, you would have seen a lot MORE perm. Instead, the perm dropped, indicating that the cylinders had a set that was rounded out during the pre-test, and then came out with flying colors up at the actual test pressure.


DG