Gas Bottles

Submitted: Sunday, Oct 08, 2006 at 04:13
ThreadID: 122977 Views:3032 Replies:5 FollowUps:2
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Reference BT Tip #45

Steve, in your Tip you refer to the number in a circle on the Gas Bottle (2 or 3) and that DOT 3 is a heavier wall/heavier Bottle.

I have checked Australian Standard AS 2469.2005 and all gas bottles are built to the same standard - 1.75mm thick for carbon steel for pressure test at 320MPa, and 1.5mm thick for stainless steel for pressure test of 360MPa.

According to the Standard, the numbers in the circle on the Carbon Steel tanks refer to the quality of coating (and therefore longevity), as follows:-

1 = Hot Dip Galvanizing - Abrasive blasted + inorganic zinc rich coating

2 = Hot Dip Galvanizing - Abrasive blasted + organic zinc rich coating.

3 = Abrasive blasted + Sprayed Zinc Coating

4 = Abrasive blasted + Red oxide or polyester powder coat.

So, you are right, the # 2 bottles will be heavier than # 3 or # 4 but not because of wall thickness. It will be because of the hot dip galvanizing vs paint.

And, if you want the best, you should be looking for a stainless steel bottle. Next will come the carbon steel with the # 1 in the circle....and so on ...down to the K-mart powder coated # 4.

That's the way I read the Standard. Unfortunately, copies of the standard are very expensive (over $100) per booklet!!!. I was able to access the full document at the Newcastle Library, and the above are from the notes I made.

For me, I'll be happy to carry # 1's or # 2's on my BT, but I would be interested to know the source and cost of stainless tanks.

Hope this is of some help to everyone.

Cheers............Rob
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Reply By: Noosa Fox - Sunday, Oct 08, 2006 at 20:20

Sunday, Oct 08, 2006 at 20:20
Rob,
I was at the Leisure Fest at Sandown on Friday and Trakmaster Vans had "2" gas cyclinders that the company owner said they get from a Caravan Supply company, and he said that he wasn't aware of any difference in the grades or what the number in the circle meant. Some of the other vans had "4" and I didn't see any with "3" on them.

We have had one of each on our van for years because before I was aware that there was a number in a circle, one of our original cylinders had a faulty refill valve so I did an exchange with it and naturally got a "2" as the replacement.

Brian
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AnswerID: 569489

Reply By: Bushtracker - Monday, Oct 09, 2006 at 18:54

Monday, Oct 09, 2006 at 18:54
Rob,
I have not cut open any bottles to measure the wall thickness. But they are heavier and it is noticable. I think they are heavier due to wall thickness, as even the exposed metal on the base and top is thicker, on the comparisons of the bottles that I made.

This will vary from Manufacturer to Manufacturer, but the ones I have seen are thicker metal. Take a Transport approved bottle and compare it to the BBQ bottles like a K-Mart and you will see the difference, at least that was the way they were when I did the tests about 10 years ago. I would be surprised if it was not still true but maybe.... There was a dramatic weight difference back then...

However, I am not going to argue the point, because you might be right now... I WILL ARGUE SOMETHING THOUGH, so that others will not have missed the point altogether. The EXCHANGE BOTTLES ARE ILLEGAL. The weight issue aside (I believe I am still correct having compared them) the issue is only TRANSPORT APPROVED bottles are legal. If you van burns up due to the wrong bottles, it could compromise your Insurance, OK? K-mart sorts are DOT 3 (This is an American started stardard that meant (Department of Transportation DOT). Anyways if my research is outdated and the wall thickness is the same, it is still an INSURANCE AND TRANSPORT DEPARTMENT ISSUE.. OK? Newbies, don't swap them out for DOT 2 at the service station, they are not legal...

On the Yachts we had the same Transport approved issues, but in those days we used heavy wall LPG tanks in Aluminium. They were really thick alloy and heavy, and essentially non-corrosive. I don't know if they are legal here, but they worked well on the yachts.

Best Regards, Not to argue, but trying to look after everyone as best I can... Ranger
AnswerID: 569490

Follow Up By: Bushtracker - Monday, Oct 09, 2006 at 19:03

Monday, Oct 09, 2006 at 19:03
I might be confusing someone on the numbers with that Posting, but it means DO NOT swap out your good legal DOT 2 for the DOT 3 or 4 at the gas exchange bottle places.. OK?
Regards, Ranger
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FollowupID: 846446

Reply By: Noosa Fox - Wednesday, Oct 11, 2006 at 05:21

Wednesday, Oct 11, 2006 at 05:21
Steve,
Could you please inform us where you are getting the information from that says that Cylinders with numbers other than "2" are illegal. as posted below.

However, I am not going to argue the point, because you might be right now... I WILL ARGUE SOMETHING THOUGH, so that others will not have missed the point altogether. The EXCHANGE BOTTLES ARE ILLEGAL. The weight issue aside (I believe I am still correct having compared them) the issue is only TRANSPORT APPROVED bottles are legal. If you van burns up due to the wrong bottles, it could compromise your Insurance, OK? K-mart sorts are DOT 3 (This is an American started stardard that meant (Department of Transportation DOT). Anyways if my research is outdated and the wall thickness is the same, it is still an INSURANCE AND TRANSPORT DEPARTMENT ISSUE.. OK? Newbies, don't swap them out for DOT 2 at the service station, they are not legal...

I might be confusing someone on the numbers with that Posting, but it means DO NOT swap out your good legal DOT 2 for the DOT 3 or 4 at the gas exchange bottle places.. OK?
Regards, Ranger

When you supplied us with our van in 2001 it was fitted with two 9 Kg LPG cylinders with "3" stamped in the circle. When one had a faulty valve I swapped it at a service station for a "2" in a circle and just about every 9 Kg cylinder that I have seen on caravans now have either a "2" or "4" in a circle.

The "3" was made in Thailand and has a Tare of 9.75 Kg
I have checked two "2" that were made in Australia with a tare of 8.0 kg and 7.92 kg.

Since Rob started this topic I have been making some checks on the Internet and cannot find anywhere that states that these 9 kg LPG cylinders on a caravan require a Transport Department Approval.
One reply email is as follows;-
"""The numbers relate to surface finish with 1 being the highest and 4 the lowest and is defined in AS 1596.

Regarding usage, the earlier gas installation code AG 601 forbade the use of the mark 4 (painted finish) cylinders with caravans and motorhomes, but this restriction was withdrawn with the publication of the later AG 5061 - 2002.

As far as I am aware there is not a heavier gauge cylinder for mobile use - it is not mentioned in the Standard.""""

The only mention I can find of LPG cylinders that require anything different, are those that are used to provide fuel to power vehicle engines, and they are filled with Auto Gas and have to comply with a lot of other regulations that these 9 kg cyclinders on caravans are not required to comply with.

As you supplied our van with a "3" and the ones you get at most service stations are "2", I am very confused as to what you are saying is illegal when you swap to another "2" at the service stations.

Brian
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Follow Up By: Bushtracker - Wednesday, Oct 11, 2006 at 19:14

Wednesday, Oct 11, 2006 at 19:14
Well,
You got me there Brian. I have updated myself on the AGA Gas Authority and Qld Transport requirements. It seems they have relaxed some of the regulations in recent years due to Manufacturers. It appears that as one Company takes over the next as in Primus and Kookaburra, they can use the protective coatings and get through the 2 or 3 just fine from what we can tell.

I may be obsolete now in my studies on the Gas Bottles. I would however suggest that people at least get the Zinc type coating. The exchange places are full of white cheap paint BBQ bottles. The latest is that the DOT 2 and 3 are relaxed a bit. If you are going to exchange bottles, get ones that are not out of date (They have to be certified and valves changed) and get ones that have the zinc coating.

I still suggest people not swap them out, get yours filled. Ranger..

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FollowupID: 846447

Reply By: Pothole - Wednesday, Oct 11, 2006 at 19:57

Wednesday, Oct 11, 2006 at 19:57
All We are the proud second owners of an 18ft BT and the gas cylinders are stamped with a 3 . We were advised to have them refilled by the previous owners for all the mentioned reasons . When I questioned why the previous owner stated that BT had given him this advice when he purchased the van.

By the way, " Beer comes in bottles and gas comes in cylinders" LOL

Regards Keith
AnswerID: 569492

Reply By: Tellem Bugrem - Friday, Oct 13, 2006 at 04:36

Friday, Oct 13, 2006 at 04:36
G'day Gas Geezers,

My humble apologies folks, I made an error in quoting the Australian Standard AS 2469 - 2005. The categories which are stamped (1 to 4) in a circle on the top of the cowall surrounding the valve assembly are as follows:-

1 = Hot Dip Galvanizing

2 = Abrasive blasted + inorganic zinc rich coating + organic zinc rich coating.

3 = Sprayed Zinc Coating

4 = Red oxide or polyester powder coat.

In my brief reading of the Standard, I found no reference to DOT. So, Steve, I presume that yours is a recollection of an American Standard which may have been applicable here before the Australian Standard was written. Mind you, I wonder why our bureaucrats have to develop an Australian Standard in mechanical engineering items such as gas bottles, when there are sound, proven regulations operating in other countries. Why can't we just adopt the best of them. No, we have to set up a committee, laboratory, and even a whole new office, just to establish another regulation!!

Still, it could be worse.... with each state having its own Standards Department....just like we have Main Roads, Vehicle and Caravan Registrations, Driver Licencing, National Parks, Motoring organisations, Royal Flying Doctor Service etc etc. Wouldn't it be wonderful to abolish State Governments and have consistency over the whole country.

Steve, could your observations of apparent differences in metal thickness be related to different thickness of the coating? Obviously, hot dip galvanizing (1) will produce an overall thicker bottle than two coats of Zinc Rich(2), or a single coat sprayed zinc (3) and certainly much thicker than the K-mart powder coat (4)

Steve, I do recall some doubt in your original Tip on this matter, and that you asked if anyone could provide a correction to, or confirmation of, your understandings.....

Well, this is my contribution, and again I apologize for my mistake in transposing my notes that I made at Newcastle Library. Liz says it's just another "Seniors Moment" !!

Cheers...............Rob
AnswerID: 569493

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