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Anybody seen these?

3K views 24 replies 12 participants last post by  sailaway21 
#1 ·
I was in the propane-gettin' place today and they had a new product, well, new for this area. Anybody seen these? Composite propane bottles. They don't explode, and you can see the fuel level through the wall of the vessel. Our local marine store wants $183 for a small aluminum bottle, but the small composite (2.5 gallons?) is $69, which the propane guy said was "a little expensive right now." Lighter than the aluminum one too.
http://www.litecylinder.com/index.html
 
#4 ·
Gee -- my boat still has an old aluminum tank without the overfill protection fitting. Buying one of these composite ones probably would be as cheap as finding a place that would retrofit my current tank. (I've already checked locally with no luck. Have to go farther afield to find someone to do it.)
 
#6 ·
very nice, I wondered when someone would do something like this. Composite tanks have been used for years for ultra high pressure cylinders but for some reason never made it to propane (resin compatibility issues with propane?) Since they CAN'T corrode, they'd be ideal for marine use. Now if only they'd make propane that was lighter than air...
 
#7 ·
As of now it looks like they're producing 10, 20, and 33lb tanks. Not sure how they keep from exploding, but the video is interesting. Site says to email for more info and sneak peeks at future developments, so it looks like more to come. Dunno about USCG approval, but I'm sure it's in the works.
Score one for fiberglass and resin!
 
#8 ·
fiber tanks are woven and impregnated with resins. They are commonly made out of carbon or kevlar and are usually for ultra high pressure situations (hydrogen storage is 10,000 psi and thats where this sort of unit shines). I can't recall the specifics right now, but there is something about the woven nature of the bottle that makes it much stronger than metal (for it's given weight of course. A similar 10,000 psi bottle in steel would be impractical for portable storage) I've also seen some made out of fiberglass but they are usually very heavy low pressure units for pool filters and stuff. Fiber bottles are also used by car modders for those niffy gas injection systems and to be cool... I guess...

The really interesting thing about these guys is that they are translucent so maybe they really are fg. Sure is nice to actually see your propane level.
 
#10 ·
SailorMitch said:
Gee -- my boat still has an old aluminum tank without the overfill protection fitting. Buying one of these composite ones probably would be as cheap as finding a place that would retrofit my current tank. (I've already checked locally with no luck. Have to go farther afield to find someone to do it.)
Sailormitch, from your avatar, it looks like you're in the Annapolis area. I had the same problem and found a place near Annapolis to retrofit my aluminum tank. It cost about $30. The place is located on the east side of Solomon's Island Rd., south of Annapolis. It's near the shopping plaza where the small West Marine is located, and on the same side of the road. I don't remember the name of the place, but it's something like Annapolis Gas, or Anne Arundel gas. It only took about 30 minutes to do, and they did it while I waited.
 
#12 · (Edited)
Before I retired in October 2005, I ran the program in the U.S. DOT that monitored the compliance for hazmat packaging, including compressed gas cylinders. My inspectors went to companies that manufactured such packaging for compliance with U.S. regulations.

I note that the "Progress" link on the web site indicates that as of 2005 or 2006, they were about to begin production of "DOT approved" 20-lb. cylinders. If they are now on sale, one assumes they received that approval, but I am checking with my old mates to confirm this.

New packaging technology for hazmat is accommodated through a "special permit" program (used to be called an "exemption" program). New packaging has to meet or exceed current regulatory requirrments. If it does, it gets a special permit number that must be marked on the packaging. Those who have seen these cylinders should find a "DOT-SP" marking followed by four or five numbers. The old exemption program required "DOT-E" followed by four or five numbers.

Composite tanks have been around for years, and are widely used as dive tanks and oxygen tanks for fire fighters. Most also have a 15-year useful life, at which time they are supposed to be disposed of.
 
#13 ·
"retrofit my current tank."
There used to be a place selling OPV valves online for about $9.95 if you wanted to do the retrofit youself. As usual, caution needs to be taken for sparks and explosive gasses. But with the added expense of recertifying older cylinders...they may not be worth retrofitting, IIRC if they are more than 5 years old some places won't fill them without charging you another $30++ to recertify them. And some places that swap tanks (rather than filling while you wait) will just take your old tank, regardless of valve and date, and swap it for you. Places that do BBQ supplies are more likely than marine suppliers.<G>

Sailinjay-
"Composite tanks have been around for years, and are widely used as dive tanks" Composite SCUBA tanks?? To the *civilian* market in the US? AFAIK not at all.
 
#14 · (Edited)
Hello--

The DOT defines any cylinder with a pressure above 900 psi as "high-pressure" and any cylinder below that as "low-pressure." In reality, most high-pressure cylinders are above 2,000 psi and most low-pressure cylinders are below 500 psi.

The normal requalification period for high-pressure cylinders is every five years, but some can go longer if in dedicated service, i.e., the same gas all the time. Low-pressure cylinders dedicated to propane use, such as gas grill tanks, can go 12 years before needing requalification. You are correct that many places simply swap out older tanks for newer tanks just to avoid the hassle.

I'll do some checking and get back to you on the point about the composite SCUBA tanks.
 
#16 ·
I stand corrected

Hellosailor--

I checked with my sources and you are correct: there are no composite tanks currently approved for dive tanks. I am told that approval is being sought for such usage, but the DOT engineering staff says that it is highly unlikely given what one would expect regarding the issue of corrosion by salt water.

Also, the cylinders manufactured by the Lite Cylinder Co. are authorized by DOT special permit (DOT-SP-13957) and the DOT engineers indicate they are excellent.
 
#17 ·
Jay, I would have expected an FRP tank to be immune to the corrosive effects of salt water, certainly more so than metal tanks which always suffer galvanic problems are (for steel) rust pitting as well. But the entire dive market is a small one, perhaps the bottom line is simply that there isn't a big enough market to cover the costs of getting FRP tanks certified--and then fighting the existing distributors to get them into stores. I've heard some ugly tales about distribution in the dive shop business. Then too there are issues about US vs global distribution, often the standards conflict and the same product can't simply be sold to a global market. And if the tanks can hold higher pressure (like NASA's throw-away tanks used in the Apollo program) the dive shops won't like that either, because new compressors cost money.
 
#18 ·
hellosailor said:
And if the tanks can hold higher pressure (like NASA's throw-away tanks used in the Apollo program) the dive shops won't like that either, because new compressors cost money.
I don't think you would see dive shops buy new compressors. They can't pay for the ones they have.

The problems I see with composite scuba tanks is

a) They will be very boyant at the end of a dive (not good).

B) A scuba tank is used quite differently than most other tanks in that they get pressurized 3000 to 3500 lbs quickly and much more often, some times two or three times a day, than say a propane tank.

C)When a air is compressed it generates heat and will that heat cause a composite tank to degrade over time? not to mention the continual stresses of refilling. Which is why steel and aluminum tanks need to be tested regularly.

D) Many divers dive nitrox which is a higher level of O2 than air. When filling a tank with nitrox mix the tank is often partially filled with 100% oxygen then filled the rest of the way with air. 100% Oxygen and hydrocarbons don't play well together. Is a composite tank going to hold 100% Oxygen without any adverse affects?

E) Did you ever see the way divers treat their tanks? :eek:
 
#19 ·
Sailormon6 said:
Sailormitch, from your avatar, it looks like you're in the Annapolis area. I had the same problem and found a place near Annapolis to retrofit my aluminum tank. It cost about $30. The place is located on the east side of Solomon's Island Rd., south of Annapolis. It's near the shopping plaza where the small West Marine is located, and on the same side of the road. I don't remember the name of the place, but it's something like Annapolis Gas, or Anne Arundel gas. It only took about 30 minutes to do, and they did it while I waited.
Sailormon -- I live near Baltimore and get to Naptown quite often, so thanks for the tip. I'll check them out next time I go down that way.
 
#21 ·
"The object of diving gas mixtures is to reduce the oxygen fraction"
The object of what mixtures for what purposes?
In sport diving, the object was to neither reduce nor enrich the percent of oxygen, but to use standard air.
But standard air "is" close to an 21% oxygen 78% nitrogen mix, and for some 20 years now sport divers have been using oxygen ENRICHED air mixes under some trade names like Nitrox(r). By enriching the oxygen content (raising the percent) you can easily decrease the nitrogen and associated problems of the bends, while still avoiding the problems of oxygen toxicity (and outright flammability) that start getting very much worse around 40% oxygen.
Thw two "standard" Nitrox mixes give you, roughly, one more group each in the decompression tables, or that much more safety if you use those mixes with the old air tables, because they have less nitrogen content and not enough oxygen to become dangerous.
 
#22 ·
hellosailor is obviously a diver as I am.
I do dive Nitrox and the point is that when you fill a nitrox tank you use 100% O2 to a partial pressure of say 1000 psi. the balance 2500 psi is then filled with air so you end up with a 02 content of say 32%. It's that initial partial fill of 100% that I wonder if the composite material will react to. As Hellosailer stated, o2 over 40 % and hydrocarbons react badly. The composite material is made from hydrocarbons. Is it inert in that state? I don't know. But thats besides the point almost all of the divers I know couldn't afford a compposit tank anyway.
 
#24 ·
Easy to misread. Heck, the Nitrox folks would have you believe they bottle magic, as opposed to the folks who just call it "oxygen enriched air".<G> Aviators got it easy, at normal air pressure oxygen is way less toxic.

How many Nooze Reports still talk about SCUBA divers and their "oxygen" tanks? And they've got staff to check on that kind of stuff.<G> Me, I've got gills. I just take the tank down so I don't scare the locals.<G>
 
#25 ·
I would suspect all of the concerns raised would be concentrated in one area of a composite dive tank; the FRP to regulator receiver coupling. At some point you have to put a discharge orifice on the tank and heat, high pressure, abuse, and intended use are all going to expose any inherent weaknesses in the design. BTW, the less symetrical the tank the weaker it is going to be. With propane tanks being nearly spherical and scuba tanks being quite elongated I'm sure there are issues with the higher pressures used in them.
 
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