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Post by Deleted on Feb 22, 2006 7:12:47 GMT -8
Chuck
What suggestions do you have for a good compressor? Do you approve of conversions and or used ones.....?? How difficult would it be to convert a std compressor...say a old store rieffer two stage?
I have 10 tanks right now......3 sets of doubles, 2 alum. 50's and 2 steel 72's.......it would be cheaper (I think) to pump my own........if I knew anything about compressors, which I don't...........and don't want to get burned dollar wise with a crappy one..........
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Post by SeaRat on Feb 22, 2006 8:16:02 GMT -8
Mossback,
If you decide to go get a compressor, be sure to have the air tested by a certified lab initially and periodically to Grade D Breathing Air standards.
John
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Post by Broxton Carol on Feb 22, 2006 9:29:23 GMT -8
I have had a number of compressors over the years. Right now I own a small Cornelius free stander model .130R1500 This model has an integral electric motor, and was a top of the line portable back in the 50's and early 60's. They were not cheap when new, and were a nice product. It has its moisture seperator right on it. Works like a charm, so simple, a treat to own and use. My Cornelius was built in 1959, and I just filled a tank with it to keep it limbered up! There are all kinds of surplus compressor heads, Kidde, and Cornelius on ebay, that came from flame throwers to bomber apparatus. These all have to be RIGGED UP, and considering all the headaches doing so, its cheaper to get a small compressor MADE for filling DIVING CYLINDERS. You will see the flame thrower compressors for 600 dollars. Dont waste your time. or money. The antique engines on them arent strong enough to develope the pressures that many claim they will make. One dude said he pumped 4500 psi with his. I owned several, and none would do over 2500 EVER. Remember, that whatever you buy in surplus, you will need a seperator to drain the oil/air droplets from the air supply. These arent cheap. I have seen them for 185.00 and the whole compressor they come on isnt worth that! Some people convert these to 5 horse honda power, but by the time you get all the accessories, and get it converted, you could have got a REAL dive compressor cheaper!!! Get you a Bauer compressor. They were built rugged for hard use, and they are often on ebay. I prefer the PURUS model. I have owned, and restored 6 of them. I still have one, that everybody has seen at the vintage dives. It runs non stop, and fills 100 psi a minute. That from a FLAT tank. These machines have their own seperator, and air filter, that you can re pack yourself. The factory replacements are a rip off, and are NOT cheap. You can buy a newer Bauer, say a junior for 2250.00 if your lucky, but Ive had several, and sold them, prefering my PURUS, as it can be carried by one person. The junior will break your back. I might have a really PRIME purus to sell soon. Anyone interested, contact me. Now some of you are asking, why is he selling it if its so good. Answer is "I have two of them"!! ;D Have a nice dive guys and gals!
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Post by treasureman on Feb 22, 2006 9:58:08 GMT -8
I just finisheds the hassle of getting twin steel 50's VIP.
I had to go to three different dive shops because the shop monkeys as they are so aptly referred to did not know their rules and regs.
Shop number one would not fill, or vip any tank that did not have a TC stamp on it (transport canada), they also wanted 50 bux for each tank to tumble them. No brainer, went to second shiop
Shop number two said the tanks are lined and needed to be condemened.
Ran out of there with my twin beauties to shop number 3
Shop three was presented with questions about linings, and thanks to Luis for providing PSI info on the tanks, they agreed that a lining was no reason to condemn the tanks, did the vip, passed and now they are safely home from their dive shop journey
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Post by duckbill on Feb 22, 2006 10:33:37 GMT -8
Steel tanks usually do not qualify for plus signs after the second and subsequent hydrostatic tests. Ron I don't want to open another can of worms, but this is simply NOT TRUE (at least here in the USA). I don't have time to dig up th wording on this at this time, but suffice it to say I own the following cylinders with current + ratings: 1961 Steel 72 on 7th hydro good to 2009 WITH PLUS RATING 1972 Steel 72 on 6th hydro good to 2009 WITH PLUS RATING And, TWO 1971 Steel 50s on 3rd hydro good to 2010 WITH PLUS RATINGS The sad fact of the matter is that it is very difficult to get a hydro facility that is not too lazy to do the little extra work involved in doing the additional calculations to get you that +10%. So, they usually lie or plain don't know, and tell you what you just said in your post. As far as not "qualify"ing for a plus rating, it is very uncommon for a cylinder to qualify for a non-plussed hydro which would not qualify for the plus. Steel cylinders almost always fail due to damage by fire or corrosion. They (should I say "never"?) almost never wear out from filling to the rated pressure.
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Post by treasureman on Feb 22, 2006 10:34:59 GMT -8
Intersting. the hydro station that did my twin 50's stated they would not overpressure the tanks to give them the plus rating for 10% overfill.
Why would they not test for this?
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Post by duckbill on Feb 22, 2006 10:42:08 GMT -8
Intersting. the hydro station that did my twin 50's stated they would not overpressure the tanks to give them the plus rating for 10% overfill. Why would they not test for this? Check the original factory hydro. If they were not originally designed for the 10 % "plus" rating there will be no plus rating on the original factory hydro. If there is a "+" there, then the dive shop and/or the dive shop's hydro guy was either ignorant or lazy. Remember, "would not" is NOT the same as "could not"!
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Post by Deleted on Feb 22, 2006 10:57:28 GMT -8
Isn't a 10% test just a bit more stretch (in laymans terms) with the reduction to normalacy the same? If so, why would STEEL tanks not pass, if they will pass the std. hydro?
I'll ask for the + next time I have some done.....my USD's are due .......and they have a + on the original
Duckbill,
What is your take on USD having the same run of tanks in the same year having the 10% + on some and not on others, such as yours and mine?......what gives 45 years ago at that factory? I'll check my twins manuf. numbers tonight and publish them for comparison to yours.....would be interesting.......
Can anyone else hazard a guess? Just curious!
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Post by Deleted on Feb 22, 2006 10:58:16 GMT -8
Chuck
Thanks for the info, will be emailing ya on yer extra pumper.....
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Post by Captain on Feb 22, 2006 11:27:02 GMT -8
173.302(c) Special filling limits for specifications 3AA cylinders. This is the regulation which permits 10% over-fill of certain steel cylinders. Steel cylinders may be over-filled by 10%, provided:
Such cylinders are equipped with frangible disc safety relief devices (without fusible metal backing) having a burst pressure not exceeding the minimum prescribed test pressure Such cylinders were last tested or retested by the water jacket method for DOT 3AA cylinders the average wall stress shall not exceed 67,000PSI or the maximum wall stress shall not exceed 73,000 psi maximum. These figures in no way represent the pressure of gas in the cylinder, This wall stress is the internally (within the steel itself) distributed force-per-unit-area mechanical reaction of the steel resulting from he deformation (stretching of the steel) An external and visual examination made at the time of test or retest shows the cylinder to be free from excessive corrosion, pitting or dangerous defects. That a plus sign (+) be added following the test date marking on the cylinder to indicate compliance with (c)(2), (c)(3) and (c)(4) above.
Someone correct me if I am wrong but the + rating does not imply a higher test pressure only the calculation necessary to determine that it is within the allowable stress range. Any comments Luis.
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Post by duckbill on Feb 22, 2006 12:08:12 GMT -8
Isn't a 10% test just a bit more stretch (in laymans terms) with the reduction to normalacy the same? I believe the plus rating is only based on additional calculations, not additional pressure testing. Someone else could elaborate on that one. I'll ask for the + next time I have some done.....my USD's are due .......and they have a + on the original Good luck; and I mean that. Shop around, if you have to and are able, until you find one who says they will do it for you. Duckbill, What is your take on USD having the same run of tanks in the same year having the 10% + on some and not on others, such as yours and mine?......what gives 45 years ago at that factory? I'll check my twins manuf. numbers tonight and publish them for comparison to yours.....would be interesting....... The only explanation I can offer is that my cylinders are older than yours- maybe even different manufacturers. Here is the data on my 38s: TANK A brand : U.S. Divers finish : yellow/galv. markings: ICC3AA1800 ser. # : 14035 other : U.S.DIVERS CORP. 1045 BROXTON AVE. L.A.24 CALIF. COMPRESSED AIR ONLY RENE hydro : 7/54 1/64 6/69 9/77 6/91(C229) 5/05(D206) last vis : 5/05 by Aqua Divers, Yuba City TANK B brand : U.S. Divers finish : yellow/galv. markings: ICC3AA1800 ser. # : 14497 other : U.S.DIVERS CORP. 1045 BROXTON AVE. L.A.24 CALIF. COMPRESSED AIR ONLY RENE hydro : 7/54 1/64 6/69 9/77 6/91(C229) 5/05(D206) last vis : 5/05 by Aqua Divers, Yuba City
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Post by Deleted on Feb 22, 2006 12:13:21 GMT -8
Duckbill
Yeah yours are older....my original hydro's are in 1961....yours are 7 years older.......I'll have to get the other info tonight.....
cheers.............
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Post by Broxton Carol on Feb 22, 2006 12:19:58 GMT -8
This parroting can go on forever? Get you a compressor and go diving, and kiss the dive store bye bye! ;D
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Post by Captain on Feb 22, 2006 12:37:19 GMT -8
The +10% over pressure was started during World War ll so that already existing cylinders could contain more gas to help the war effort provided they passed the additional calulations during re testing.. Rather than engineering and manufacturing higher capacity cylinders it was an easy way to increase capacity without using steel needed for other uses( guns, tanks, ships, etc.) to manufacture cylinders.
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Post by duckbill on Feb 22, 2006 12:41:47 GMT -8
Isn't a 10% test just a bit more stretch (in laymans terms) with the reduction to normalacy the same? I believe the plus rating is only based on additional calculations, not additional pressure testing. Someone else could elaborate on that one. I'll ask for the + next time I have some done.....my USD's are due .......and they have a + on the original Good luck; and I mean that. Shop around, if you have to and are able, until you find one who says they will do it for you. Also, cylinders today have the REE number stamped on the shoulder, so looking up the specs and calcs for hydros is quite simple. The hydro facilities have to research older tanks for this data and most shops really don't like to. I am fortunate to have one nearby which takes care of us with older steel tanks. In addition, since Luis' qualifications were questioned earlier, I'd like to say I feel he has one of the most informed, level-headed, and analytical minds regarding SCUBA technicalities. His posts are well thought out and tactful and I've never found him to be wrong. Credentials are not necessary where common sense prevails, though his credentials are impressive. JMHO.
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